Traffic Criteria Manual - Colorado Springs · Page 6 Traffic Criteria Manual ENGINEERING CRITERIA...

ENGINEERING CRITERIA MANUAL

SECTION IIITraffic Criteria

Manual


Page II

TableofContents

Section1.0 Introduction................................. 6

Section2.0 TrafficControlDevices ............................ 7

Section3.0 AccessControl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83.1 StateHighways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83.2 CityStreets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Section4.0 SightDistanceRequirements . . . . . . . . . . . . . . . . . . . . . . . . 94.1 ApproachSpeed.......................................94.2 HorizontalSightDistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .94.3 VerticalSightDistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104.4 IntersectionSightDistance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104.5 ResidentialDrivewaySightDistance . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Section5.0 IntersectionSpacing. . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Section6.0 AccessDesign ...............................126.1 AccessGrades . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .126.2 AccessDesign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .126.3 InternalCirculation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Section7.0 Medians .................................13

Section8.0 Channelization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158.1 TurnChannelApproaches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .158.2 TurnLaneDesign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

Section9.0 GradeatIntersections . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Section10.0 AngleofIntersection,MinimumIntersectionCurbRadii...........21

Section11.0 InstallationofCurbs,Mid-blockWalkways,PedestrianRamps,andGuardrails 2211.1 TypesofCurb. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2211.2 Mid-BlockWalkways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2211.3 PedestrianRamps. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2211.4 Guardrails. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

Section12.0 Cul-De-SacRegulations . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Section13.0 PrivateStreets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Section14.0 StreetNames. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2514.1 Approval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2514.2 DuplicationofNames. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2514.3 ContinuityofNames . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2514.4 SmallCul-de-sacs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2514.5 StreetNameDesignations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25

Section15.0 RoadwayStandards . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2615.1 StandardsforFreeways. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26


Page III

15.2 StandardsforExpressways. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2715.3 StandardsforPrincipalArterialStreets. . . . . . . . . . . . . . . . . . . . . . . . . . .2815.4 StandardsforMinorArterialStreets. . . . . . . . . . . . . . . . . . . . . . . . . . . .3015.5 StandardsforCollectorStreets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3115.6 StandardsforResidentialStreets..............................3315.7 StandardsforMinorResidentialStreets . . . . . . . . . . . . . . . . . . . . . . . . . .3415.8 StandardsforIndustrialStreets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3615.9 StandardsforAlleys. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37

Section16.0 TableofTrafficEngineeringDesignStandards . . . . . . . . . . . . . . . 39

Section17.0 TransitServices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Section18.0 Definitions,Abbreviations,andAcronyms. . . . . . . . . . . . . . . . . 43

Section19.0 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

AppendixA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

SectionTrafficImpactStudyGuidelinesforDevelopmentProjects . . . . . . . . . . . . . 45

AppendixB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

SectionStandardUtilityLocations.............................53

AppendixC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

SectionRoundaboutDesignGuide . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Section1.0 IntroductiontoRoundaboutDesignGuide. . . . . . . . . . . . . . . . . 54

Section2.0 GeneralDesignCriteria. . . . . . . . . . . . . . . . . . . . . . . . . . 552.1 AppropriateRoadways/Locations. . . . . . . . . . . . . . . . . . . . . . . . . . . . 552.2 ApproachandCirculatorySpeeds. . . . . . . . . . . . . . . . . . . . . . . . . . . . .552.3 DesignVehicle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .562.4 Pedestrian/Bicycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .572.5 DesignSoftware ......................................572.6 Utilities&Drainage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .582.7 Landscaping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 582.8 Other . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58

Section3.0 Specific/GeometricDesignElements. . . . . . . . . . . . . . . . . . . . 603.1 ApproachRoadway . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .603.2 CirculatingRoadway. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 613.3 SightDistance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .613.4 SplitterIslands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .623.5 CentralIsland. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .623.6 SigningandMarking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 633.7 LandscapingDesignElements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64

Section4.0 Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74


Page IV

FiguresFigure1 SightDistance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Figure2 LowDensityResidentialDriveways. . . . . . . . . . . . . . . . . . . . . .11Figure3 MultiFamilyResidentialDrivewaysandCommercialAccesses . . . . . . . . .11Figure4 Right-In,Right-out,Left-inMedianDesign. . . . . . . . . . . . . . . . . . .13Figure5 MedianDesigntoRestrictExitingLeftTurns . . . . . . . . . . . . . . . . . .14Figure6 MedianOpeningsforIntersectionsandMedianIslandEnds . . . . . . . . . .14Figure7 GuidetoBasicExclusiveTurnLaneElements. . . . . . . . . . . . . . . . . .16Figure8 DesignElementsforLeftandRightTurnLanes. . . . . . . . . . . . . . . . .17Figure9 Cul-De-SacRequirements . . . . . . . . . . . . . . . . . . . . . . . . . . .23Figure10 CrossSectionsforPrincipalArterialStreet(TypeI) ................29Figure11 TypeII(6-Lane,142’Right-of-Way) . . . . . . . . . . . . . . . . . . . . . . .30Figure12 MinorArterial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31Figure13 Collector(WithParking). . . . . . . . . . . . . . . . . . . . . . . . . . . .32Figure14 Collector(WithoutParking) . . . . . . . . . . . . . . . . . . . . . . . . . .32Figure15 Residential(Local)Streets(DetachedSidewalk) . . . . . . . . . . . . . . . . .34Figure16 Residential(Local)Streets(AttachedSidewalk) . . . . . . . . . . . . . . . . .34Figure17 MinorResidential(Local)Streets(DetachedSidewalk) ..............35Figure18 MinorResidential(Local)Streets(AttachedSidewalk) . . . . . . . . . . . . . .35Figure19 IndustrialStreets................................36Figure20 ResidentialAlleys. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38Figure21 CommercialAlleys. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38


Page V

Tables

Table1 SightDistance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Table2 SummaryofExclusiveTurnLaneRequirements . . . . . . . . . . . . . . . .15

Table3 RequiredDecelerationLaneandTaperLengths . . . . . . . . . . . . . . . .18

Table4 DecelerationLaneGradeAdjustmentFactors. . . . . . . . . . . . . . . . .18

Table5 DesignCriteriaforAccelerationLanes . . . . . . . . . . . . . . . . . . . . .19

Table6 GradeAdjustmentFactorsforAccelerationLanes . . . . . . . . . . . . . . .19

Table7 RedirectTapersforThroughLanes. . . . . . . . . . . . . . . . . . . . . . .20

Table8 RequiredStorageLengthsforStop-ControlledIntersections . . . . . . . . . .20

Table9 MinimumIntersectionCurbRadii. . . . . . . . . . . . . . . . . . . . . . .21

Table10 TrafficEngineeringDesignStandards(Freeways,ExpresswaysandArterials) . . . . . . . . . . . . . . . . . . . . .39

Table11 TrafficEngineeringDesignStandards(Collector,Residential[Local],PublicAlley,Industrial,andCommercialFrontage) . . . . . . . . . . . . . . . . . . . . .40

Page 6 TrafficCriteriaManual


1.0 Introduction

Thismanualprovidesrecommendedstandardsfortrafficrelateddesignissues.TheyareintendedtosupplementtheEngineeringCriteriaManualoftheCityofColoradoSpringsandareaimedatensuringconsistentengineeringdesignpracticesandprovidinganadequatecorridorfortheplacementofpublicstreetinfrastructurewithinthecitylimits.CityEngineeringwilladheretothesepoliciesascloselyaspossiblewhenreviewingroadwaydesignproposalswhetheritisfornewdevelopmentorforaCityfundedproject.TheCityEngineerandhisauthorizedrepresentativesmaygrantvariancesfromanyofthesepolicieswhentherearepracticaldifficultiesthatpreventtheapplicationofapolicyandifthegrantingofsuchvariancewillnotbedetrimentaltothepublicsafety.FlexibilitywillbeusedintheCity’sinterpretationandapplicationoftheserequirementswhensuitablejustificationisprovidedforalternativedesignsolutions.

AlternativedesignstandardsmayapplyforprojectsthatinvolveTraditionalNeighborhoodDesign,MixedUseDevelopment,SmallLotPUDDevelopment,TrafficCalmingDesign,andHillsideDesign.TheappropriateCitymanualsforprojectsinvolvingthesedesignsshouldbeconsulted.Whenthetermspeedisusedinthismanualitreferstothepostedspeedofthestreet.Designspeedistypically5mphabovethepostedspeed.

TrafficImpactStudies(SeeAppendixA)anddesignplansforstreetsinnewdevelopmentsandredevelopmentprojectsmustbesubmittedtotheEngineeringDevelopmentReviewDivisionofCityEngineering.TrafficStudiesandplansforCityfundedprojectsmustbesubmittedtoCityEngineering’sRoadwayTeam.SometrafficstudiesarecommissionedbythetransportationsectionofEconomicDevelopment’sComprehensivePlanninggroupandshouldbesubmitteddirectlytothem.

Thefiguresprovidedinthismanualareillustrativeonly.Theyarenottoscaleandarenotintendedtobeusedfor/asengineeringdesign.Forsimplicity,somedesignelementssuchassidewalksorbicyclelaneshavebeenleftoffcertainfigures.



2.0 Traffic Control Devices

ThetypeandlocationoftrafficcontroldevicesusedoncitystreetsmustbeapprovedbyCityEngineering.Trafficsignalsshouldbeusedwherenecessary,butalternatetrafficcontrolsuchasstopsignsorroundaboutswillbeconsideredfirst.

Whenitcanbeshownthataparticularzoningaction,masterplan,ordevelopmentplanimpactsthestreetsystemtoapointthatatrafficsignaliswarrantedaccordingtoManualonUniformTrafficControlDevices(MUTCD)andapprovedbyCityEngineering,thedevelopershallberesponsibleforalloraportionofthesignalinstallation.Formoreinformationaboutadeveloper’sresponsibilityfortrafficsignalparticipationandfinancialassurancespleasereferenceSection10.5oftheSubdivisionPolicyManual.



3.0 Access Control

3.1 State Highways

AccessontoStateHighwaysintheCitywillbesubjecttostipulationscontainedintheStateofColorado,StateHighwayAccessCode.AllaccessestoandfromStateHighwayswillrequireapermitwhichmustbeobtainedfromandapprovedbytheColoradoDepartmentofTransportation(CDOT).AllaccessesfromnewdevelopmentsontoStateHighwaysrequireCityEngineeringreview.

3.2 City Streets

Thedesign,number,andlocationofaccessdrivesshallbeapprovedbyCityEngineering.Thenumberofaccessdrivesshallbeabalancetoallowforefficienttrafficflowwhileprovidingadequateaccesstoprivateproperty.CityEngineeringrealizesthattheadequacyofaccesspointsisacriticalissueintheeconomicsuccessofcommercialdevelopmentsandredevelopmentareas.Thefollowinginformationispresentedasageneralguidelineforthelocationofaccessdrivestopublicstreets.

1. Provisions of Access–Propertyownershavetherightofreasonableaccesstothepublicstreetsystem.ThismanualprovidesstandardsforapprovingaccesstotheCityStreetsystembasedonthestreetclassification.Ifapropertycannotbeservedbyanyaccesspointmeetingthesestandards,CityEngineeringshalldesignateaccesspoint(s)basedontrafficsafety;operationalneeds,economicdevelopment,andconformancetoasmuchoftherequirementsoftheseguidelinesaspossible.Accessdrivesshallnotbeapprovedforparkingorloadingareasthatrequirebackingmovementsinapublicstreetright-of-wayexceptforsinglefamilyorduplexresidentialusesonlocalstreets.

2. Restriction of Turning Movements–Wherenecessaryforthesafeandefficientmovementoftraffic,CityEngineeringmayrequireaccessdrivestoprovideforonlylimitedturningmovements(e.g.,rightturnsonly).

3. Number of Access Drives–OneaccessdriveperpropertyownershipshallbepermittedwhichmaybejointlysharedwithadjacentpropertiesunlessasiteplanorTrafficImpactStudy(TIS)approvedbyCityEngineeringshowsthatadditionalaccessdrivesarerequiredtoadequatelyhandledrivewayvolumesandwillnotbedetrimentaltotrafficflow.PropertieswithextensivestreetfrontagemaybegrantedmorethanonepointofaccessinaccordancewithsafetrafficengineeringdesignandwidthsasreferredtoinSection 5.0andincompliancewithmajorstreetaccesscontrolstandards.

4. Sight Distance Requirements–TheminimumsightdistanceshallbeprovidedatallaccessdrivesasshowninSection 4.0.



4.0 Sight Distance Requirements

Sightdistanceisoneofthemostimportantdesignissuestobeconsideredfortrafficsafety.Beforeanyaccesstoacollectororhigherstreetclassificationisapproved,CityEngineeringwillreviewdesignplansforadequatesightdistanceatintersections.

4.1 Approach Speed

Thespeedusedfordeterminingminimumenteringsightdistancerequirementsisassumedtobethepostedspeedlimit.IfCityEngineeringhasreasontobelievethattheoperatingspeedissubstantiallydifferentthanthepostedspeedtheycanrequestthatthe85thpercentilespeedbeusedtodeterminesightdistance.Inthecaseofanewfacility,thedesignspeedshouldbeused.Formodifiedcul-de-sacs(knuckles,eyebrows,teeturnarounds,etc)sightdistancemustbeprovidedbasedontheexpectedoperatingspeedofthelocation.

4.2 Horizontal Sight Distance

Thedistanceshallbemeasuredfromthecenteroftheapproachlaneatapointfifteenfeet(15’)behindtheflowlineoftheintersectingstreettothecenterofthenearestapproachingtrafficlaneforeachdirection.RefertoFigure 1.

Figure 1 Sight Distance



4.3 Vertical Sight Distance

Thedistanceshallbemeasuredtoallowadriverattheheightof3.5feettoseeanobject2.0feetabovetheroadwayattheminimumsightdistancedescribedbelow.Forfurtherdetails,refertoAPolicyonGeometricDesignofHighwaysandStreets,AmericanAssociationofStateHighwayandTransportationOfficials(AASHTO)2004,Chapter3,“ElementsofDesign/VerticalCurves.”

4.4 Intersection Sight Distance

Theminimumsightdistanceatallpublicandprivatestreetintersectionsoraccesses,anddrivewaystocollectorstreetsorgreatershallfollowtheguidelinesbelow.AtnotimeshalltheminimumsightdistancebelessthantheAASHTOstoppingsightdistance.

Table 1 Sight Distance

Speed of Thru Roadway (MPH)

Minimum Sight Distance for Stopped

Vehicle (FT)

Grade Correction Distance (FT)

Upgrade To: Downgrade To:

3% 6% 9% 3% 6% 9%

15 80 0 -5 -10 +5 +10 +20

20 115 0 -5 -10 +5 +10 +20

25 280 0 -10 -20 +10 +20 +30

30 335 0 -10 -20 +10 +20 +30

35 390 -10 -15 -25 +10 +25 +40

40 445 -10 -20 -30 +10 +30 +50

45 500 -15 -25 -30 +15 +40 +60

50 555 -20 -35 -45 +20 +50 +70

4.5 Residential Driveway Sight Distance

Theprevioussightdistancecriteriadoesnotapplytosingle-familyback-outdriveswheresightdistancewillbeprovidedbasedonlocationofthedriverseyewhencommencingtheback-outmaneuver.Toprovidesightdistancefromdrivewaystoboththestreetandsidewalkitemstallerthanthree(3)feetshouldnotbeplacedwithinfive(5)feetoftheedgeofdriveway.Thisrestrictionextendsfromtheedgeofstreettoten(10)feetbehindthebackofsidewalk.Thisrestrictionincludessolidsurfacefencesandlargeshrubs.Utilitypoles,firehydrants,openlyspacedtrees,andtrafficdevicesareallowableifvisualobstructionisminimal.



5.0 Intersection Spacing

EachhighdensityresidentialandcommercialaccessshouldbeseparatedataminimumbyadistanceequaltothestoppingsightdistancedescribedintheTable of Traffic Engineering Design Standards inSection 15.Whendecelerationoraccelerationlanesareorwillberequired,itisdesirablethattheaccessesbeseparatedbyasufficientdistancesothatthespeedchangelanesincludingtransitiontapersdonotoverlap.Accessshouldnotbeplannedwithintheacceleration,deceleration,taperorstoragelengthsofotheraccesspointsorintersections.RefertoFigures 2 and 3. Thecenterofcommercial/multi-familyaccessesnotinalignmentwillnormallybeoffsetaminimumofonehundredfiftyfeet(150’)onalllocalandcollectorstreets;threehundredfeet(300’)onallarterials.Theoff-setofintersectionsmayneedtobeadjustedtoaccommodateadequateleftturnstoragelength.

Figure 2 Low Density Residential Driveways

Figure 3 Multi Family Residential Driveways and Commercial Accesses



6.0 Access Design

6.1 Access Grades

CommercialorhighdensityresidentialaccessthatmaybesignalizedinthefutureshallmeetthegradestandardsforsignalizedCitystreets(See9.0).Nonsignalizedcommercialorhighdensityresidentialaccessdrivesshouldprovideagradeof4%orlessatthestreetapproach.

6.2 Access Design

Commercialorhighdensityresidentialaccessshallbeaminimumof24feetinwidth.Widthsgreaterthan36feetmustbeapprovedbyCityEngineering.Drivewaysshallhaveaminimumcurbreturnof15feet.Drivewaysintersectingprincipalarterialsshallhaveaminimumcurbreturnof20feet.

6.3 Internal Circulation

PrivateinternaltrafficcirculationoncommercialsitesisreviewedbyLandUseReviewatthetimeofdevelopmentplan.EDRDreviewsaccessesontothepublicstreetandrelatedissues,butEDRDdoesnotreviewprivateinternaltrafficcirculation.Asneeded,EDRDprovidessupporttotheLURplannerorcanmediatebetweenLURandanapplicantaboutinternalcirculationissuesifrequested.Theonlyexceptionsareschoolsites.CityEngineeringreviewsinternalcirculationonschoolsites.CityEngineeringsupportsthedevelopmentplancriteriainSection7.5.502oftheCodewhichasks,“Havetheinternaldrives,externalaccesspoints,andpedestrianwalkwaysbeendesignedtoprovidesafeandconvenientvehicularandpedestrianaccesswithintheproject?”



7.0 Medians

Raisedmediansshallberequiredonprincipalarterialsandmaybeallowedonlocals,collectorsandminorarterials.AlldesignsaresubjecttoreviewandapprovalbyCityEngineering.RefertoFigures 4, 5, and 6.

IfrequiredbyCityEngineeringorrequestedbythedeveloper,allraisedmediansshallbeaminimumofseventeenfeet(17’)inwidth(faceofcurbtofaceofcurb).Alongprincipalarterialdesignsofsixlanesormore,themedianwidthshallbenolessthantwenty-eightfeet(28’)faceofcurbtofaceofcurb.OpeningsinexistingmediansmustbeapprovedbyCityEngineering.

Theuseof3/4intersectionmediandesignandchannelized“T”intersectionsrequireamedianwiderthantheminimum17’median.A22’medianwidthissuggestedwherethesedesignsareanticipated.

Medianopeningsvoidofleftturnlanesshallbedesignedinthebulletnoseconfiguration,withallowancesforpedestriancrossings.Leftturnlanesshallbedesignedtoaccommodatethe20-yearleftturnvolumebasedonthe95%queueoftheleftturn.

Figure 4 Right-In, Right-out, Left-in Median Design



Figure 5 Median Design to Restrict Exiting Left Turns

Figure 6 Median Openings for Intersections and Median Island Ends

Thissketchisforathreelegintersection.Iftheintersectionhasfourlegs,theleftsidewillalsohaveanauxiliarylaneforleftturns,andthemedianontheleftsidewillhavethesameconfigurationastheoneontherightsiderotated180degrees.



8.0 Channelization

Leftorrightturnlanesmayberequiredalongcollectororarterialroadwaysifdeemednecessaryforthesafeandefficientflowoftraffic.Thedesignofsuchlanesshallbebasedon20-yeartrafficprojectionsforthatroadway.Thedesignwillconsistofadequatetaperlengths,decelerationoraccelerationlength,storagecapacity,andturninggeometrics.Theinstallationcostswillberequiredofthedeveloperifitisdeterminedthatamajorproportionofitsneediscreatedbytheimpactofaproposeddevelopment.

8.1 Turn Channel Approaches1. Exclusive Turn Lane Requirements - Exclusiveleftturn,rightturn,andacceleration

lanesshallbeprovidedwhereverleftturn,rightturn,oraccelerationlanesarespecifiedasbeingneededbyanapprovedTrafficImpactStudy(TIS).TherequirementsforuseofturnlanesareshowninTable 2.

Table 2 Summary of Exclusive Turn Lane Requirements

Left Turn Lane Left Turn Acceleration Lane Right Turn Lane Right Turn

Acceleration Lane

Expr

essw

ay Aleftturnlaneisrequiredforanyaccessthatallowsleftturningressmovement.

Aleftturnaccelerationlanemayberequiredifthedesignwouldbeabenefittothesafetyandoperationoftheroadway.

Arightturnlaneisrequiredforanyaccesswithaprojectedpeakhourrightturningressturningvolumeof10VPHorgreater.

Arightturnaccelerationlaneisrequiredforanyunsignalizedaccesswithaprojectedpeakhourrightturnegressturningvolumeof10VPHorgreaterforroadwayswithpostedspeedsof50mphorgreater.

Prin

cipa

l Art

eria

l Aleftturnlaneisrequiredforanaccesswithaprojectedpeakhourleftingressturningvolumeof10VPHorgreater.

Aleftturnaccelerationlanemayberequiredifitwouldbeabenefittothesafetyandoperationoftheroadway.

Arightturnlaneisrequiredforanyaccesswithaprojectedpeakhourrightingressturningvolumeof25VPHorgreater.

Arightturnaccelerationlaneisnotrequired.



Left Turn Lane Left Turn Acceleration Lane Right Turn Lane Right Turn

Acceleration Lane

Min

or A

rter

ial Aleftturnlane

isrequiredforanyaccesswithaprojectedpeakhouringressturningvolumeof25VPHorgreater.

Anaccelerationlaneisgenerallynotrequired.

Arightturnlaneisrequiredforanyaccesswithaprojectedpeakhourrightturningvolumeof50VPHorgreater.

Anaccelerationlaneisnotrequired.

Note:Turnlanerequirementsonlowerclassificationroadstobedeterminedonacase-by-casebasisdependingonrecommendationsfromatrafficimpactstudyandapprovedbyCityEngineering.

2. Lane Shifts or Drops Required - Laneshiftsordropsshallbeprovidedwhereverredirectionoftrafficisspecifiedasbeingneededbyanapprovedsigningandstripingplan.

3. Conflicts between Exclusive Turn Lanes-Wheretwointersectionshaveexclusiveturnlanesthatoverlap,ortheendingpointsoftheexclusiveturnlaneshavelessthan300feetorone-halftheirlengthofseparation(whicheverisshorter)andasignificantstructureortopographicalfeaturedoesnotprecludewidening,acontinuousexclusiveturnlaneshallbeestablishedbetweentheintersectionstoimproveroadwayconsistency,safety,andtomaintainedgeofpavementcontinuity.

Ifrestrictivetopographyallowsonlyoneexclusiveturnlane,normallyaleftturndecelerationlaneisgivenfirstpriority.Wherethetravellanesmustberedirectedduetotheadditionofaleftturnlane,apavementoverlayisrequired.

8.2 Turn Lane Design

Turnlanestypicallyconsistofacombinationofseveralcomponents(i.e.tapers,lanelength,andstorage).Theuseanddesignofthesecomponentsvariesbasedonthetypeofaccess,roadwayclassification,andsite-specificconditions.Figures 7 and 8 presentagraphicalguidetobasicexclusiveturnlaneelements.

Figure 7 Guide to Basic Exclusive Turn Lane Elements



*Additionallengthmayberequiredforstorageturningvehiclesatpotentialcontrolledintersections.

Figure 8 Design Elements for Left and Right Turn Lanes

NOTE:Thisfullintersectiondesignisasymmetrical.LeftTurnandThruLanesmustalignwiththeoppositeintersectionapproach.

1. Deceleration/Acceleration Lanes

a. Deceleration LengthThebasisfordesigningadecelerationlaneandtaperistoprovidesufficientlengthforavehicletodecelerateandbrakeentirelyoutsidethethroughtrafficlanes.Table 3providestherequireddecelerationlaneandtaperdesignlengthsbyspeed.Decelerationlanelengthsshallbeadjustedforagradeof3%ormoreusingthefactorsinTable 4.Therequiredlengthallowsamotoristtodecelerateingearforatleast3secondsfollowedbysafebrakingtoacompletestop.Whendesignconstraintsnecessitatereducingpartofthedecelerationlength,thetapershallbereducedfirstandthenthedecelerationlength.AllreductionsindecelerationlanelengthmustbeapprovedbyCityEngineering.



Table 3 Required Deceleration Lane and Taper Lengths

Speed (MPH) Lane Length (feet) Approach Taper (feet) Total Length (feet)

25 115 120 235

30 115 120 235

35 120 140 260

40 155 160 315

45 200 180 380

50 235 200 435

60 290 240 530

70 SpecialDesign SpecialDesign SpecialDesign

Table 4 Deceleration Lane Grade Adjustment Factors

Roadway Grade Factors

Upgrade

3%to4.9% 0.90

5%to7.5% 0.80

Downgrade

3%to4.9% 1.20

5%to7.5% 1.35

b. Bay Tapers Forarterialstreetsthestraightlinetapershouldbereplacedwithabaytaper(asymmetricalreversecurve).Thebaytapershouldbeatleast1/3thelengthoftheappropriatestraightlinetaper.Theturn-offcurveshouldbeapproximatelytwicethesizeofthesecondcurve.AdesigndetailforabaytaperisavailableinAASHTO,Exhibit9-95.



c. Acceleration LengthThebasisfordesigninganaccelerationlaneandtransitiontaperistoprovidesufficientlengthforavehicletoacceleratetotheappropriatespeedandmergeintothethroughtrafficlaneswithoutdisruptingtrafficflow.Table 5providestherequiredaccelerationlaneandtransitiontaperdesignlengthsbyspeed.AccelerationlanelengthsinTable 5shallbeadjustedforagradeof3%ormoreusingthefactorsinTable 6.Wheredesignconstraintsnecessitatereducingpartoftheaccelerationlane,thetaperlengthshouldbereducedfirst.AllreductionstoaccelerationlanesmustbeapprovedbyCityEngineering.

Table 5 Design Criteria for Acceleration Lanes

Speed (MPH) Lane Length (feet) Straight-line Taper (feet)

40 236 12:1

45 388 13.5:1

50 580 15:1

60 930 20:1

70 1290 25:1

Table 6 Grade Adjustment Factors for Acceleration Lanes

Speed (MPH)

40 to 50 60 70

Upgrade

3to4.9% 1.3 1.5 1.7

5to7.5% 1.5 2.0 2.5

Downgrade

3to4.9% 0.7 0.65 0.6

5to7.5% 0.6 0.55 0.5

d. Redirect TapersWhenconstructingaroadwaythatwilldirectlyconnectwithanexistingroadwayofadifferentwidth,itisnecessarytoinstallaredirecttaperbetweenthetwo.Redirecttapersshallbeusedwhereanexclusiveturnlane(droplane),medianorotherredirectionofvehiclesisnecessaryandwhereredirectionoftheflowoftrafficisnecessarytoaccommodatetheexclusiveturnlaneormedian.RedirecttapersshallbeinstalledinconformancewithTable 7.Theseratiosarenottobeusedinthedesignofacceleration,deceleration,orstoragelanes.Iftheredirecttaperwouldresultinahorizontalcurvedesigndeficiencyforthethroughmovement,thehorizontalcurveshallbecorrected.Redirecttapershouldbedesignedasstraighttaperswiththebeginningandendingpointsrounded.



Table 7 Redirect Tapers for Through Lanes

Speed (MPH) 20 25 30 35 40 45 50 55 60 65 70

Straight Taper Ratio

10:1 12.5:1 15:1 20:1 25:1 30:1 45:1 50:1 55:1 60:1 65:1

2. Storage Lengths for left turn lanes

Thelengthofaleftturnlaneforallcitystreets,otherthanexpressways,shallbebasedonprovidingadequatestoragelength.Decelerationlengthisnottobeincludedfortheleftturnlanedesign.

Thebasisfordesigningthelengthofrequiredstorageistoprovidesufficientlengthforvehiclestoqueuewithinthelanewithoutaffectingothermovements.Table 8providestherequiredstoragelengthsforstop-controlledintersections.IfCityEngineeringdeterminesthatmeetingtherequiredstoragelengthisimpracticalorresultsinanunsafecondition,theminimumstoragelengthshallbebasedonthemeanarrivalrate,butinnocaseshalltheminimumstoragelengthbelessthan50feet.Onexpressways,leftturnlanesshallbedesignedtoincludethedecelerationlengthandstoragelength.

Table 8 Required Storage Lengths for Stop-Controlled Intersections

DHV (VPH) <60 61-120 121-180 181-250 >250

Storage Length (feet) 50-75 100 150 200 250ormore

Note:Atsignalizedintersectionstheleftturnlanestoragelengthshallbebasedonthe95%queue.



9.0 Grade at Intersections

Flatgradesarepreferredinalldirectionsfromanintersection,butinnocaseshallgradesexceedfourpercent(4%)foradistanceofatleastfifty(50)feetfromallcurbintersectionsunlessphysicalfactorswarrantspecialconsideration.Atsignalizedintersections(orintersectionsexpectedtobesignalizedinthefuture),twopercent(2%)maximumgradesarerequiredfortwohundred(200)feetineachdirectionontheapproachasmeasuredfromthecrossstreetcurbline.RefertoAASHTOStandardsfordesignofcrestandsagverticalcurves.

10.0 Angle of Intersection, Minimum Intersection Curb Radii

Proposedstreetsanddrivewaysshallintersectoneanotheratninetydegree(90°)anglesorasclosetoninetydegreesasisfeasible;nolessthaneightydegrees(80°).Thenumberofintersectionsalongarterialsshallnormallynotbespacedlessthanone-quartermile.(Apairofoffset“T”intersectionsshallbetreatedasoneintersectionforquartermilespacingpurposes).Intersectionsoflocalstreetswitharterialsshouldbe“T”intersectionstoreducethenumberofconflictingmovementsattheseintersections.When“T”intersectionsareused,thecenterlinesofthestreetsnotinalignmentshallnormallybeoffsetaminimumofonehundredandfiftyfeet(150’)onlocalstreetsandthreehundredfeet(300’)oncommerciallocals,collectors,andarterials,unlessanacceptedTISjustifiesasmallerseparation.Onarterialstreets,iftheleftturnstoragefortwo“T”intersectionsoverlap,theminimumspacingshallbeincreasedtoaccommodatetheleftturnqueues.Aminimumof100’tangentpriortobeginningofcurvemeasuredfromthecenterlineoftheintersectedstreetshallbemaintainedforallresidentialstreetintersectionsalongacollectorstreet.Atstreetintersections,theminimumcurbradiiforstandardstreetsareillustratedinTable 9.Streetintersectionswithnon-standardcrosssectionsornotatninetydegree(90)angleswillrequiretruckturninganalysisforboththewheelbaseandtheoverhangpath.ThetruckturninganalysisshallbesubmittedtoCityEngineeringforreview.Waiversoftheminimumcurbreturnradiiwillbeconsideredonacase-by-casebasiswithsufficientjustificationandinspecialzonedistricts(TND,MixedUse,etc.)

Table 9 Minimum Intersection Curb Radii

Type of Intersection Curb Radii

Local–Local 15’

Local–Collector 20’

Collector–Collector 25’

Local–Arterial 25’

Collector–Arterial 30’

Arterial–Arterial 40’



11.0 Installation of Curbs, Mid-block Walkways, Pedestrian Ramps, and Guardrails

11.1 Types of Curb

CurbandgutterisrequiredonallCitystreetsinaccordancewithSection7.7.704oftheCityCode.StandardType1,8”verticalcurbandgutterorequivalent6”curbmustbeusedonallCollectors,Major,andMinorArterials.RampcurbmaybeusedonresidentialstreetswhendrainageconsiderationswarrantitsusesubjecttotheapprovaloftheCityEngineer.Rampcurbshallnotbeapprovedabuttingmulti-family,commercial,industrial,parkorschoollanduses.Inallcasesthesamecurbtypeshallbeusedonbothsidesofthestreet.

Streetswithoutcurbswillbeconsideredonacase-by-casebasisiftheproposeddevelopmentisdesignedasaLowImpactDevelopment(LID)anduniquestreetcrosssectionshelpachievethedesiredgoalofincreasedstormwaterinfiltration.

11.2 Mid-Block Walkways

CityEngineeringmayrequireaconcretemid-blockwalkway,notlessthansix(6)feetinwidth,onlocalandcollectorstreetswhenitisdeemednecessarytoprovideaccesstoschools,shoppingcenters,transportationfacilities,orothercommunityfacilitiesandservices.

11.3 Pedestrian Ramps

PedestrianrampsshallbeinstalledasrequiredbyCityEngineeringperCityofColoradoSpringsPedestrianRampdesigndetailascontainedintheCityofColoradoSpringsCityEngineeringStandardSpecificationsasrequiredbyOrdinance(7.7.704-E3).

11.4 Guardrails

GuardrailsshallbeinstalledasrequiredbyCityEngineeringperAASHTOwarrantsandshallcomplywithAASHTOdesignguidelines.



12.0 Cul-De-Sac Regulations

Thedesignandoveralllengthofacul-de-sacshallbedeterminedbytopography,typeofdevelopment,proposeddensity,andotherphysicalfactorswhichmaywarrantspecialconsideration.Theoveralllengthofacul-de-sacstreetnormallyshallnotexceedfivehundredfeet(500’).Thecul-de-sacwillgenerallybedesignedwithaturn-aroundright-of-wayradiusoffiftyfeet(50’)inresidentialdevelopmentandsixtyfeet(60’)inindustrialdevelopmentandwitharadiustocurbflowlineofforty-twofeet(42’)inresidentialdevelopmentandfiftyfeet(50’)inindustrialdevelopment,seeFigure9.Alternatecul-de-sacdesigngeometrywillbeconsideredonacase-by-casebasiswithsufficientjustificationwhendesignconstraintsexistorwhenLIDorotherspecialzonedistrictgoalsarebeingincorporatedinthedesign.

Modifiedcul-de-sacs(knuckles,eyebrows,teeturn-around,etc.)canbeusedonlocalstreetsaslongassightdistancecriteriacontainedinsection4.2ismet.Forexample,aknuckledesignona90degree(90o)curve wouldneedtoprovideadequatesightdistancebasedona15mphdesignsincethatwouldbetheexpectedoperatingspeedofavehiclemakinga90degree(90o)turn.Sightdistancecanbeprotectedbyadditionalright-of-wayorprovidinglegalrestrictionsforlandscaping,buildings,fences,andotherobjectsthatwouldblockadriver’sview.Anyrestrictionsforsightdistancepurposesshallbeidentifiedonthedevelopmentplan.Allcul-de-sacdesignsmustmeetFireCodeprovisionsforcul-de-sacs.

Figure 9 Cul-De-Sac Requirements



13.0 Private Streets

PrivatestreetsareacceptableinnewdevelopmentatthediscretionofthedeveloperandsubjecttoCityreview.Section7.7.704(C)oftheCityCodestatesthatthelocationanddesignofprivatestreetsissubjecttothereviewandapprovalofTrafficEngineering[administeredbytheEngineeringDevelopmentReviewDivision(EDRD)]andtheFireDepartment.ThisreviewisdoneatthetimeoftheDevelopmentPlan.EDRDapprovalisnotrequiredonthedesignplansandprofilesforprivatestreetsexceptforintersectionswithapublicstreet.Gatedresidentialcommunitiesmustuseprivatestreets.Thedevelopermustmakefinancialarrangementsfortheperpetualownershipandmaintenanceofprivatestreets(i.e.ahomeowners’association)toincludelife-cyclerepairandreplacementofthefacilities.EDRDrequiresthatthereceptionnumberoftheassociatedrecordeddocumentsbereferencedonthefinalplat.Citypolicyrequiresthatprivatestreetsbedesignedstructurally(i.e.pavementthickness)tomeetorexceedCitystandardsandspecifications.SigningandstripingofprivatestreetsmustbeconsistentwiththeManualforUniformTrafficControlDevices(MUTCD).



14.0 Street Names

14.1 Approval

StreetnamesandnumberingshallbesubjecttotheapprovaloftheRegionalBuildingDepartment,PoliceDepartment,FireDepartment(911),andCityEngineering.Residentialstreetnamesshallbelimitedto10letters(refertotheAddressingOrdinance7.7.704-D).

14.2 Duplication of Names

StreetnamesshallnotduplicatenorbetoocloselyapproximatedphoneticallytoanynameofanexistingCityorCountystreetinElPasoCounty.

14.3 Continuity of Names

Anystreetwhichisacontinuationoranapproximateorlogicalcontinuationofanexistingdedicatedstreetshallbearthesamenameastheexistingstreet.

14.4 Small Cul-de-sacs

Smallcul-de-sacswhichhavelessthanfiveinteriorlotsmaybeomittedfornamepurposeswhenthehousenumbersarecontinuouswiththoseofthestreettowhichtheyhaveaccess.

14.5 Street Name Designations

Streetnamedesignationsshallbeusedasfollows:

1. Boulevard or Parkway–ShallbereservedforroadwaysdesignatedontheIntermodalTransportationPlanhavingamediandividerofsufficientsizetoallowforlandscaping.(Example:ResearchParkway)

2. Avenue or Road–ShallbereservedforstreetsofsubstantialcontinuitysuchasprimaryorsecondarylinksoftheIntermodalTransportationPlan.

3. Street or Drive –Shallbereservedforstreetsoflesscontinuitysuchaslocalorcollectorstreets.

4. Court, Place, Circle, Way, Terrace or Lane–Shallbereservedforstreetswithnocontinuitywhatsoever,andcontainsmallnumbersoflots;usuallycul-de-sacs

5. Grove, Heights, Point, or View shallbeusedforprivatestreets.PrivatestreetsshallbesignedbythedeveloperperCityspecificationswithbrownbackground/whiteletters.



15.0 Roadway Standards

TheCityofColoradoSpringsusesaroadwayhierarchytoprovidesafeandcontinuoustravelandaccess.Afunctionalclassificationofroadwaysprovidesthehierarchyneededtoaccomplishthisgoal.Streetsaredividedintocategorieswithdifferentdesigncriteriatomaintainandprotecttheprimarypurposeoftheroadway.Theroadwaystandardsprovidedinthismanualaretoprovideastandardforstreetsections,butvariancestothesesectionscanberequested.Roadwayreductionswillbeconsideredifalessercross-sectioncanbeshowntoadequatelyaccommodatetheprojectedlong-termtrafficvolumes.Thecross-sectionsprovidedinthismanualareillustrativeonly.Therearenottoscaleandarenotintendedtobeusedasengineeringdesign.Forsimplicity,somedesignelementssuchassidewalksorbicyclelaneshavebeenleftoffcertainfigures.Thefunctionalclassificationsaredescribedbelow:

15.1 Standards for Freeways1. Function - Freewayspermitrapidandunimpededmovementoftrafficthroughand

aroundtheCity

2. Right-of-Way Widths-420feet,minimumwithfrontageroads,332feet,minimumwithoutfrontageroads

3. Number of Moving Lanes - Sixtoeightlanes

4. Access Conditions

a. Accessshallbegradeseparated

b. Interchangesshallbemadewithmajorarterialstreetsandfreewaysonly

c. Nointersectionsatgradeshallbepermitted

5. Traffic Characteristics

a. Notrafficsignals

b. Parkingprohibited

c. Bicyclesprohibited

d. Twoseparateone-wayroadwayswithadividingmedianstrip

6. Planning Characteristics

a. FreewaysshouldconnectwithmainhighwaysapproachingandleavingtheCityfromalldirections

b. FreewaysshouldbesoalignedastoservethemajortrafficgeneratorswithintheCity,suchasthecentralbusinessdistrict,majorindustrialareas,regionalshoppingcenters,etc.

c. Freewaysshouldnotbisectneighborhoodsorcommunitiesbutshouldactasboundariesbetweenthem

d. Addedright-of-wayisprovidedforlandscaping,grassplanting,addedsafety,andnoiseattenuation



e. Atinterchangeareas:

1. Fordiamondinterchanges,right-of-wayshouldflareto580’inwidthfrom1000’eachsideoftheintersectionright-of-waylineattheintersectingcrossstreet.

2. Forcloverleafinterchanges,right-of-wayshouldflareto1300’inwidthfrom1300’eachsideoftheintersectionright-of-waylineattheintersectingcrossstreet.

3. Foralternativeinterchangedesigns(SPUI’s,flyovers,etc.)ROWrequirementswillbeprovidedbasedonthedesign.

7. Design Characteristics

a. Grades

1. Notlessthanonepercent(1%)ontangents;normorethanfourpercent(4%)

b. Crosssections

1. Crosssectionswilbedeterminedbyspecificdesign

15.2 Standards for Expressways1. Function - Expresswayspermitrapidandrelativelyunimpededmovementoftraffic

throughandaroundtheCity.

2. Right-of-Way - 210feetminimum,withadditionalright-of-wayforfrontageroads,ifrequired

3. Number of Moving Lanes - Fourtosixlanes


a. Accessshallbecompletelycontrolled

b. Interchangesshallbemadewithfreewaysandmaybemadewithmajorarterialstreets.

c. Signalizedintersectionsarepermittedwitharterialstreetsonly,preferablywithonemilespacing.Signalizedintersectionsat½milelocationsmaybeallowedbyCityEngineering.

d. Turnrestrictedintersectionsmaybeallowedathalfmilespacingorwheretheycanbeshowntobenefitoperationsontheexpressway.

e. Highdensityorcongestedareasmayrequirespecificaccessplans.


a. Trafficcontroldevicesandchannelizationshallbeprovidedateachintersectionatgrade.

b. Parkingprohibited

c. Twoseparateone-wayroadwayswithadividingraisedmedian

d. Bicyclesmaybepermittedontheshoulderoronseparatedbikewaysforportionsofexpressways.




a. ExpresswaysshouldconnectwithmainhighwaysapproachingandleavingtheCityfromalldirections.

b. ExpresswaysshouldbesoalignedastoservethemajortrafficgeneratorswithintheCity,suchasthecentralbusinessdistrict,majoremploymentcenters,militaryinstallations,regionalshoppingcenters,etc.

c. Expresswaysshouldnotbisectneighborhoodsorcommunitiesbutshouldactasboundariesbetweenthem

d. Addedright-of-wayisprovidedforlandscaping,grassplanting,addedsafety,andnoiseattenuation

e. Atinterchangeareas:

1. Fordiamondinterchanges,right-of-wayshouldflareto580’inwidthfrom1000’eachsideoftheintersectionright-of-waylineattheintersectingcrossstreets

2. 2.Forcloverleafinterchanges,right-of-wayshouldflareto1300’inwidthfrom1300’eachsideoftheintersectionright-of-waylineattheintersectingcrossstreet

3. SeeFreeway#3


a. Grades

1. Notlessthanonepercent(1%)ontangentsormorethanfourpercent(4%)

b. Crosssection

1. Crosssectionswillbedeterminedbyspecificdesign

15.3 Standards for Principal Arterial Streets1. Function - Majorarterialstreetspermitrapidandrelativelyunimpededtrafficmovement

throughouttheCityandcarryhighvolumesofinterandintratrafficwhichconnectsmajorlanduseelementsaswellascommunitieswithoneanother.Majorfunctionistoservethroughtraffic.Thesecondaryfunctionistoserveabuttingproperty.Thisfunctionaldescriptionpertainstofourlaneandgreaterfacilities.

2. Right-of-Way Width - 107-142feet

3. Number of Moving Lanes - Fourtosixlanes,withleftandrightturnbays.Rightturnlanesshallbeconstructedatintersectionsofallarterialstreets.


a. Intersectionsandcurbcutsshallbelimited,asapprovedbyCityEngineering.

b. Signalizedintersectionsshallbelimitedto1/2milespacingunlessadeequatejustificationisprovidedtoapprovesignalizedintersectionsatotherlocations.

c. Mediancutswillbepermittedatmajororsignificantstreetintersections,generallyatintervalsofapproximately¼to½milesasapprovedbyCityEngineering.




a. Regulationoftrafficshallbeaccomplishedbytrafficcontroldevicesandchannelization.

b. On-streetparkingprohibited

c. Verticalcurbrequiredwithdetachedsidewalks

d. Medianshallberaisedwithcurbandgutter(CityStandardDetailD-6andD-24)

e. Highdensityorcongestedareasmayrequirespecificaccessplans.


a. PrincipalarterialstreetsshouldbespacedapproximatelyonemileapartinthesuburbanareasoftheCityto¼mileapartinareasofhighpopulationdensityandintenselandusage.

b. Principalarterialstreetsshouldnotbisectneighborhoods,butshouldactasboundariesbetweenthem.

c. Sidewalksshallbesetbackfromthestreet.

d. Ingeneral,abuttingpropertiesshouldnotfaceontheroadwayunlessseparatedfromitbyafrontageroad.Lotsthatdirectlyabutthearterialshallhaveaminimumdepthof120feet.

e. Bicycleaccessshallbepartofa4’multi-useshoulder.


a. Grades

1. Notlessthanonepercent(1%)ontangents;normorethanfourpercent(4%).Gradesofsixpercent(6%)maybeconsideredforunique,shortdistances.

b. Alignment

1. Horizontal–1040footminimumradiusatcenterlineforstandardcrownedcross-slopes

2. Vertical–minimumlengthequivalenttoKvaluetimesthealgebraicdifferenceintherateofgrade.

Figure 10 Cross Sections for Principal Arterial Streets

Type I (4- Lane, 107’ Right-of-Way)



Figure 11 Type II (6-Lane, 142’ Right-of-Way)

15.4 Standards for Minor Arterial Streets1. Function - Minorarterialstreetspermitrapidandrelativelyunimpededtrafficmovement

throughouttheCityandcarryhighvolumesofinterandintra-trafficwhichconnectmajorlanduseelements.

2. Right-of-Way Width - 90feet(withtwo5footeasements)

3. Number of Moving Lanes - Fourlanes


a. Intersectionswillgenerallybe“T”typeatgradeasapprovedbyCityEngineering.

b. IntersectionsandcurbcutsshallbelimitedasapprovedbyCityEngineering.


a. Regulationoftrafficshallbeaccomplishedbytrafficcontroldevicesandchannelization.

b. On-streetparkingprohibited

c. Verticalcurbsrequiredwithdetachedsidewalks

d. Medianswillberaised.Paintedmedianswillbeconsideredwithadequatejustifications.


a. MinorarterialstreetsshouldbespacedapproximatelyonemileapartinthesuburbanareasoftheCitytoafewblocksapartinareasofhighpopulationdensityandintenselandusage.

b. Minorarterialstreetspreferablyshouldnotbisectneighborhoods.

c. Bicycleaccessshallbepartofa4’multi-useshoulder.


a. Grades

1. Notlessthanonepercent(1%)ontangents;normorethanfourpercent(4%).Gradesofsixpercent(6%)maybeconsideredforunique,shortdistances.



b. Alignment

1. Horizontal–765footminimumradiusatcenterlineforstandardcrownedcross-slopes.

2. Vertical–minimumlengthequivalenttotheKvaluetimesthealgebraicdifferenceapprovalofgrades.

c. Frequencyofintersections

1. Intersectionsalongminorarterialstreetsshallbelimitedtoasfewaspossible

Figure 12 Minor Arterial

15.5 Standards for Collector Streets1. Function - Collectorstreetsaredesignedtoservethelocalneedsoftheneighborhood

andtoprovidedirectaccesstonon-residential,abuttingproperties.Alltrafficcarriedbycollectorstreetsshouldhaveanoriginoradestinationwithintheneighborhood.

2. Right-of-Way Width-57feet(noparking)to67feet(parking)

3. Number of Moving Lanes-Twolanes

4. Access Conditions - Directaccesstoresidentialpropertiesisbywayofcurbcuts.


a. On-streetparkingisallowedonbothsidesofminorcollectorstreetsunlessprohibited.

b. Intersectionsareatgrade


a. Sidewalkswillbedetachedfromverticalcurbs

b. Bicycletravelcanbeaccommodatedwith14’sharedlanes.

c. NoresidentialfrontageallowedoncollectorswithADTgreaterthan2500.




a. Grades

1. Notlessthanonepercent(1%)ontangents;collectornotmorethantenpercent(10%).

b. Alignment

1. Horizontalcurves–collector335footminimumradiusatcenterlineforstandardcrownedcross-slopes.

2. Verticalcurves–AminimumlengthequivalenttotheKvaluetimesthealgebraicdifferenceofapproachgrades.

c. Frequencyofintersections

1. Intersectionsalongcollectorstreetsshallbelimitedtoasfewpointsaspossible,whileprovidingcommercialaccesstoabuttingpropertiesandconnectingtolocalstreetsystem.

Figure 13 Collector(WithParking)

Figure 14 Collector (Without Parking)



15.6 Standards for Residential Streets1. Function - Designedtoservethelocalneedsoftheneighborhoodandtoprovidedirect

accesstoabuttingresidentialproperties.Alltrafficcarriedbyresidentialstreetsshouldhaveanoriginoradestinationwithintheneighborhood.

2. Right-of-Way Width - 50feetminimumplus5footeasementsoneachsideofright-of-wayforutilitiesandsidewalks.

3. Number of Moving Lanes - Twolanes

4. Access Conditions - Intersectionsareatgradewithdirectaccesstoabuttingpropertiesbywayofcurbcutsorramp-typecurbing.

5. Traffic Characteristics - On-streetparkingisallowedonbothsidesofthestreet


a. Residentialstreetsshouldbedesignedtodiscouragethroughtrafficandtoencouragetrafficspeedsof25mphorless.Thesestreetsshouldnotexceed1200feetinlengthandshouldincludegeometricfeaturesatintervalsof600’maximum.Examplesoffeaturesincludechokers(chicanes),trafficcircles,medianisland/barriers,cul-de-sacs,andcurvatures.DesigncriteriaforthesetechniquesareavailableintheTrafficCalmingDesignManual.

b. Insubdivisiondesign,residentialstreetsarediscouragedfromintersectionswithmajorandsecondaryarterialstreets.

c. Sidewalksmaybedetachedfromorattachedtothecurb,dependinguponthetypeofcurb.

d. Bicycletravelcanbeaccommodatedinthetravellanesduetothelowvolume,lowspeednatureofthistypeofroadway.


a. Grades

1. Notlessthanonepercent(1%)ontangents;normorethantenpercent(10%)

b. Alignment

1. Horizontalcurves–200footminimumradiusatcenterlineforstandardcrownedcross-slopes.

2. Verticalcurves–aminimumlengthequaltotheKtimesthealgebraicdifferenceofapproachgrades.

c. FrequencyofIntersections

1. Intersectionsalongresidentialstreetsshallbeallowedasneededtoprovideconnectionstootherlocalstreetsandcollectorstreets.



Figure 15 Residential (Local) Streets (Detached Sidewalk)

Figure 16 Residential (Local) Streets (Attached Sidewalk)

15.7 Standards for Minor Residential Streets1. Function - Designedtoprovidedirectaccesstoabuttingsingle-familyresidential

propertiesorcul-de-sacshavingalengthofnogreaterthan500feet.Apavementmatof24feetisallowedonminorresidentialstreetswhichcontainnomorethan20single-familylots.Anyotherresidentialstreethavingmorethan20single-familylotsmustinstalla28footpavementmat.

2. Right-of-Way - 47feetminimumplus5footeasementsoneachsideofright-of-wayforutilitiesandsidewalks.


4. Access Conditions - Directaccesstoresidentialpropertiesisbywayofcurbcutsorbyramptypecurbs.


a. On-streetparkingisallowedononesideofthestreet





a. Minorresidentialstreetsshouldbedesignedasshortlooporcul-de-sacstreetsonly.

b. Minorresidentialstreetsshouldnotintersectmajorarterialstreets.


a. Grades


b. b.Alignment

1. Horizontalcurves–200footminimumradiusatcenterlineforstandardcrownedcross-slopes.

2. Verticalcurves–AminimumlengthequivalenttotheKvaluetimesthealgebraicdifferenceoftheapproachgrades.

Figure 17 Minor Residential (Local) Streets (Detached Sidewalk)

Figure 18 Minor Residential (Local) Streets (Attached Sidewalk)(Servinglessthan20singlefamilylots)



15.8 Standards for Industrial Streets1. Function - Industrial/commercialstreetsaredesignedtoservefacilitieswithinindustrial/

commercialareasandtoconnectsuchareaswithmajorarterialandcollectorstreets.

2. Right-of-Way Width - 70feet(withtwo5footeasements)

3. Number of Moving Lanes - Twolanestofourlanes

4. Access Conditions - Directaccesstoabuttingindustrial/commercialpropertiesisbywayofcurbcuts.


a. On-streetparkingmaybepermittedonbothsidesofthestreet



a. Onlylocalindustrial/commercialtrafficshouldbeencouragedonindustrialstreets

b. Sidewalkswillbedetachedfromthecurbwhererequired

7. 7. Design Characteristics

a. Grades

1. Nolessthanonepercent(1%)ontangents;normorethaneightpercent(8%)

b. Alignment

1. Horizontal–335footminimumradiusatcenterline

2. Vertical–AminimumlengthequivalenttotheKvaluetimesthealgebraicdifferenceoftheapproachgrades.

c. FrequencyofIntersections

1. Intersectionsalongindustrial/commercialstreetsshallbelimitedtoasfewaspossible,whileconnectingtothecollectorstreetsystemandprovidingaccesstolocallanduses.

Figure 19 Industrial Streets



15.9 Standards for Alleys1. Function - Designedtoprovideaccesstoabuttingpropertyatrearlotlines.

2. Right-of-Way Widths - 20foot(Residential)/25foot(Commercial)



a. Provideaccesstoabuttingpropertyatrearoflots


a. Normallyalleysshallintersectatperpendicularangleswithstreets

b. Noparkingshallbepermitted


a. Alleysshallbeopenatbothends

b. Normallyalleysshallnotintersectwithcollectorstreetsorarterialstreets.


a. Grade


8. Alley Drainage

Alleysurfacesmaybedesignedtodraininthreeways.

- ConcreteV-shaped.Theentirealleymustbeconcrete.Concretepansdownthecenterofasphaltalleysarenotpermitted.

- Asphaltcrownedwithvalleyguttersoneachside,or

- Asphaltcross-slopedwithavalleygutteronthelowside.

Flowspreadinalleysshallbeconfinedtotheright-of-wayatreasonabledepths.Stormflowsinalleysshallbelimitedtotheflowsgeneratedfromtherearofthelotsadjoiningthealley.Alleyflowsshallnotcrosstheintersectingstreetsintoanotheralleybutshallbecapturedordivertedattheintersectingstreet.FormoreinformationaboutalleydesignreferenceismadetothedesignmanualsforTraditionalNeighborhoodandMixedUseDevelopment.



Figure 20 Residential Alleys

Figure 21 Commercial Alleys



16.0 Table of Traffic Engineering Design Standards

Table 10 Traffic Engineering Design Standards (Freeways, Expressways and Arterials)

Design Element Functional Classification

Freeway ExpresswayPrincipal Arterial

Type 2 (6 lane)

Principal Arterial

Type 1 (4 lane)

Minor Arterial

Speeds (1) 65 55 45 45 40

Design ADT 85,000-100,000 60,000-85,000 25,000-60,000 10,000-25,000 5,000-25,000

Trip Length Over5miles Over5miles 1-2miles 1-2miles Over1mile

Corridor ROW Width 332’-420’ 210’ 142’ 107’ 90’w/(2)5’easements

Roadway Width (pavement mat) Var.Width 2-50’

pavementmat2-40’pavement

mat2-28’pavement

mat 69’

# of Lanes 6-8 4-6 6 4 4

Lane Widths 12’ 12’ 11’ 11’ 11’

Shoulder Width 12’ 10’ 4’ 4’ 4’

Median Var.Width Raised28’ Raised28’ Raised17’ Raised17’

Sidewalk Requirement (placement) N/A N/A Detached6’ Detached6’ Detached6’

Bicycle Accommodation N/A N/A 6’Multi-Use

Shoulder6’Multi-Use

Shoulder5’Multi-Use

Shoulder

Tree lawn Width N/A N/A 7’ 7’ 7’

Parking No No No No No

Access FullControl FullControl FullControl FullControl FullControl

Design Vehicle WB67 WB67 WB67 WB67 WB50

Signalized Intersection Frequency N/A 1mile ½mile ½mile ½mile

Unsignalized Intersection Frequency 1mile N/A ¼mile ¼mile 600’

Vertical Alignment RefertoVerticalCurveDesigninAASHTOGeometricDesignofHighwaysandStreets

Horizontal Alignment Radius N/A N/A 1045’ 1040’ 765’

Grade (min-max) 1%-4% 1%-4% 1%-4% 1%-4% 1%-4%

Intersection Grade GradeSepar. 1%min 1%min 1%min 1%min

Intersection Sight Distance 775’ 665’ 500’ 500’ 445’

Stopping Sight Distance (2) 730’ 570’ 360’ 360’ 305’



Traffic Engineering Design Standards (Collector, Residential [Local], Public Alley, and Industrial)

Design Element

Collector Residential (Local)

Minor Residential

(Local)Public Alley Industrial

Speeds(1) 30 25 25 15 30

DesignADT 1,500-5,000 300-1,500 50-300 50-300 <10,000

TripLength 1mile Local Local Local TruckLocal

MaximumUninterruptedFacilityLength ¼mile 600’ 300’

AdjacentStreetLength 1mile

CorridorROWWidth

57’(noparking)

67’(parking)

50’w/(2)5’easements


20’Residential25’Commercial


RoadwayWidth(pavementmat)

28’(noparking)

38’(parking)30’ 24’(<21Lots)

28’(>20Lots)16’Residential

22’Commercial 51’

#ofLanes 2 2 2 2 3

LaneWidths 14’w/sharedbike 9’ N/A N/A 14’w/shared

bikew/12’ctl

ShoulderWidth N/A N/A N/A N/A N/A

Median N/A N/A N/A N/A N/A

SidewalkRequirement(placement)

Detached5’

Attached6’vert.curb/

Detached5’others

Attached6’vert.curb/

Detached5’others

N/A Detached5’

BicycleAccom-modation

Onstreetw/sharedlane




TreelawnWidth 7’ 7’-6” 7’ N/A 7’

Parking Allowed TwoSides One-sideparkingonly No Twosides

Access PartialControl

PartialControl

PartialControl N/A Partial

Control

DesignVehicle WB40 SU30 SU30 N/A WB67

SignalizedIntersectionFrequency N/A N/A N/A N/A ½mile

Un-signalizedIntersectionFrequency 600’ 300’max 300’max ½adjacent

streetlength 600’



Design Element

Collector Residential (Local)

Minor Residential

(Local)Public Alley Industrial

VerticalAlignment

RefertoVerticalCurveDesigninAASHTOGeometricDesignofHighwaysandStreets

HorizontalAlignmentRadius

335’ 200’ 200’ 85’ 335’

Grade(min-max) 1%-10% 1%-10% 1%-10% 1%-10% 1%-8%

IntersectionGrade 1%-3% 1%-4% 1%-4% 1%-4% 1%-3%

IntersectionSightDistance 335’ 280’ 280’ 170’ 335’

StoppingSightDistance(2) 200’ 155’ 155’ 80’ 200’

Note: Alternate design standards may apply when Traditional Neighborhood, Mixed Use, Hillside, or Low-Impact Development are used. (1) Speed refers to the anticipated posted speed. The design speed is 5 mph greater than the posted speed. (2) For level terrain only.



17.0 Transit Services

Onarterialstreetsthatareadesignatedbusroute,developerswillneedtoworkwithMountainMetropolitanTransittodeterminetheappropriatelocationofbusstopsandbusturnouts.BusturnoutsaretobeconsideredonArterialstreetswherethereisnoon-streetparking,ahighvolumeofvehiculartraffic,andpostedspeedsare40mphorgreater.Busbays,openbusbays,andqueuejumperbusbaysareallacceptabledesignsforbusturnouts.ThegeneralguidelinesandstandarddetailsforbusturnoutsareavailablefromMountainMetropolitanTransit.



18.0 Definitions, Abbreviations, and Acronyms

AASHTO–AmericanAssociationofStateHighwayandTransportationOfficials

Accesses–Commercialentrancesandexits.

ADT–AverageDailyTraffic

Algebraic Difference in Grades (%)–Thenumberderivedbysubtractingtheapproachanddepartingtangentgrades(%)ofacurve.

Asymmetrical Reverse Curve–Opposingcurvesofthesameradius.

CDOT–ColoradoDepartmentOfTransportation

Design Speed–Safeandcomfortabledrivingspeed.Usually5MPHoverthepostedspeed.

DHV–DesignHourVolume

Driveways–Residentialentrancesandexits.

Fc–FaceofCurb

K Value–Thelengthofaverticalcurvedividedbythealgebraicdifferenceofapproachgrades.

MPH–Milesperhour

Posted Speed–Thespeedlimitplacedonthesignsnexttotheroadway.

TIS–TrafficImpactStudy

VPH–VehiclesPerHour



19.0 References

- APolicyonGeometricDesignofHighwaysandStreets,AmericanAssociationofStateHighwayandTransportationOfficials(AASHTO)5thEdition,2004

- APolicyonGeometricDesignofRuralHighways,AASHTO,2004

- TransportationandTrafficEngineeringHandbook,InstituteofTransportationEngineers(ITE),1999

- UrbanTransportationOperations–TrainingDesignofUrbanStreets,U.S.DepartmentofTransportationFederalHighwayAdministration(USDOT–FHWA),1982

- ASurveyofUrbanArterialDesignStandards,InstituteforMunicipalEngineering–AmericanPublicWorksAssociation(APWA),1969

- SubdivisionPolicyManual,CityofColoradoSprings,1980Update

- ManualonUniformTrafficControlDevices,USDOT–FHWA,2003

- GuidelinesforDrivewayDesignandLocation,ITE,1985

- GuidelinesforUrbanMajorStreetDesign,ITE,1985

- ResidentialStreets,UrbanLandInstitute(ULI),NationalAssociationofHomeBuilders(NAHB),AmericanSocietyofCivilEngineers(ASCE),1977

- TripGeneration,7thEdition,ITE,2003

- 2010PavementDesignManual,ColoradoDepartmentofTransportation(CDOT)



Appendix A

Traffic Impact Study Guidelines for Development Projects

Purpose

Thepurposeoftheseguidelinesistoprovideauniformmethodologyforthetrafficengineeringconsultantstouseinconductingtrafficimpactstudiesforproposeddevelopmentprojects.ThecomplianceoftheseguidelineswillresultinthetimelyreviewbyCityEngineeringandreducedrevisions.

Atrafficimpactstudy(TIS)willberequiredforaproposednon-residentialdevelopmentwithapeakhourtripgenerationofover100vehicles,oranyproposedresidentialdevelopmentwith150ormoredwellingunits.TheforecastvolumeshallbebasedontripgenerationratescontainedinthelatesteditionoftheTripGenerationManualpublishedbytheInstituteofTransportationEngineers(ITE)orotherratesasapprovedbyCityEngineering.

AllTISsfornewsubdivisiondevelopmentshallbesubmittedtotheEngineeringDevelopmentReviewDivision(EDRD)ofCityEngineering.EDRDwillreturnreviewcommentstothepreparer.WhenthereviewprocessiscompleteandtheTISisreadyforapproval,EDRDrequirestwocopiesbesubmittedforCitysignature.Additionalcopiescanbesubmittedandwillbereturnedtotheengineer.Thesecopiesshallbeproperlycertified,signed,sealed,anddatedbytheregisteredprofessionalengineerresponsibleforthereport.ThesignatureblockforEDRDshallreadThisTrafficImpactStudyisherebyacceptedbyCityEngineeringwithalinefortheEDRDreviewer’ssignatureanddate.FollowingEDRDapprovaloftheTISascannedPDFversionoftherecordapprovedreportandplansmustbereceivedbyEDRDpriortorecordingtheFinalPlat.



Thefollowingtypesofsubmittalswhichexceedthetripgeneration/dwellingunitcriteriawillrequireaTIS:

1. Amasterplanordevelopmentplansubmittal.

2. Anyrezoningapplication.

3. Apreliminarymaporfinalplatifthepropertyhasalreadybeenrezonedfortheproposeduseandnotrafficstudywasrequiredfortherezoning,ortheoriginaltrafficstudyismorethantwoyearsold.

4. Priortoissuanceofabuildingpermit,ifthepropertyhasalreadybeenzoned/plattedandnoprevioustrafficstudylessthantwoyearsoldexists.

5. ForaStateHighwayAccessPermit,if:

a. SiteaccessisrequiredoffaStateHighwaypriortoissuingabuildingpermit.

b. AdditionalaccessoffaStateHighwaytoanexistinguseisbeingrequested.

c. AnychangeofuseaffectingaccessfromtheStateHighway.

6. ForanapplicationforannexationintotheCity.

7. Theapplicantwillberequiredtosubmitanewtrafficstudyif,aftersubmittingtheoriginaltrafficstudy,thelanduseintensityandtrafficgenerationisincreasedbymorethan15%.

8. OtherconditionsasdeterminedbyCityEngineering.

9. CityEngineeringmayrequireothermemos,letters,analyses,orotherdocumentationtoaddressspecifictrafficissuesatstaffdiscretion.

ThetrafficstudyshallbeconductedbyaprofessionalengineerregisteredintheStateofColoradowithadequateexperienceintrafficengineeringand/ortransportationplanning.

Methodologies

Thestudyshallbeconductedusingthefollowingmethodologies.

ThepreparerofthetrafficstudyshallmeetwithCityEngineering.Atthismeeting,thefollowingitemswillbeaddressed:

- Establishmentofthestudyarea

- Identificationoftheanalysisperiods(AM,PM,Weekend)tobestudied

- Theforecastyears(openingyearandhorizonyear)

- Tripgenerationassumptions

- Methodologytoobtaintripdistributionandassignmentassumptions

- Identificationofhighaccidentlocationsoroperationaldeficienciestobeaddressedaspartofthestudy

Itisrecommendedthattheapplicantsubmitthecompletedforecastsofbackgroundtraffic,projecttripgeneration,tripdistribution,andtripassignmenttoCityEngineeringforreviewpriortothefulltrafficanalysis.



Impactsofthedevelopmentontheexistingandproposedroadwaynetworkshallbeidentified.Intersectiontrafficanalyses(includingprojectdriveways)shallbeconductedusingtheoperationalmethodologiesdescribedinthelatesteditionoftheHighwayCapacityManual(HCM).

TrafficanalysisconductedusingSynchroorothercomputersoftwareproductsshallusethefollowingsettingsunlessotherwiseapprovedbyCityEngineering:

- PeakHourFactor(PHF):0.88Rural;0.92Urban

- CycleLength:between60secondsand120seconds;higherandlowercyclelengthsrequirepriorapprovalbyCityEngineering.

- YellowTime:3.0secondsminimum;followITEguidelines

- All-RedTime:2.0seconds

- TheCityrecognizestheHCMlevelofservice(LOS)asthenationallyacceptedstandardforLOS.HCMreportsshallbeusedforLOSresultsinSynchro,notSynchro’sownLOScalculations.

LOSfiguresshouldshowtheLOSresultsforeachintersectionapproachaswellastheoverallintersectionLOS.

Mid-blocktrafficanalysesshallbebasedonvolumetocapacityratiosusingthefollowingcapacityvalues:

Roadway Classification ADT

PrincipalArterials(8Lane) 65,000



MinorArterials 25,000

MajorCollectors 10,000

MinorCollectors 3,500

Local 1,500

MinorLocal 300

Industrial-Commercial 10,000

FrontageRoad 5,000

Mid-blockanalysisshallbeusedonlywhereintersectionanalysisdoesnotadequatelyaddresscapacityconcerns.Atlocationswherethe“withproject”scenarioanalysesindicateintersectionapproachLOSDwillbeexceededand/ormidblockLOSCwillbeexceeded,thestudyshallidentifymitigationmeasuresorexplainwhymitigationisnotneeded.ThemitigationmeasuresshallincludeimprovementsthatwillprovideLOSDorbetteratintersectionapproachesandLOSCorbetteratmidblocklocations.Themitigationmeasuresshallbepresentedwithdrawingstoclearlyshowtheexistingandproposedimprovements.



TheneedfornewtrafficsignalsshallbeevaluatedusingthewarrantsinthelatesteditionoftheManualonUniformTrafficControlDevices(MUTCD).NonewtrafficsignalsshouldbeproposedthatcannotbejustifiedusingMUTCDtrafficsignalwarrants.Trafficprogressionisofparamountimportance.Allpotentialsignalizedintersectionsshouldbeplannedfor½mileintervals.Allotherlocationstobeconsideredshallmeetthefollowingcriteria:

- Theprogressionpatterncalculationshalluseacyclelengthbetween60and120seconds.Efficiency(e)equalsBandwidth(BW)inthatdirectioninsecondsdividedbythecyclelength(C)insecondsandmultipliedby100toobtainapercent.e=BW/Cx100.Aminimumefficiencyof30%shallbeachieved.Thoseintersections,whichwouldreducetheprogressionefficiencytobelow30%ifasignalwereinstalled,shallremainunsignalizedandhaveturningmovementlimitedbydrivewaydesignormedianislands.

- Submittalofatime/spacediagramwithacceptablethroughbands,cyclelengths,andprogressionspeeds.

- InareasthatmayaffectestablishedcomplexcomputerizedprogressionsanydeviationfromexistingconditionsshallbethoroughlyaddressedandapprovedbyCityEngineeringpriortoapproval.

- Thegreentimeallowedtothecrossstreetshallbeconsiderednolessthanthetimethatisrequiredforapedestriantocrossthemainlineatfourfeetpersecond.

Weaveanalysesforpotentiallyaffectedlocationsmayberequiredforthestudy.ThisanalysisshouldbeconductedusingHCMmethodologiesand/ormicro-simulationmodelingbyanapprovedmicro-simulationmodel.

Traffic Study Format

Specificrequirementswillvarydependingonthesitelocation.However,alltrafficstudiesshallcontain,asaminimum,thefollowinginformation.Seethe“RequiredFiguresandTablesMatrix”todeterminetherequiredexhibits.

1.0 Introduction

% Purposeofthereport

% Studyobjectives

2.0 AreaConditions

% StudyAreaLandUse

• Existinglandusesonthesiteandinthevicinity

• Existingzoningonthesite

• Approvedfuturedevelopmentonothersitesinthevicinity

% SiteAccessibility

• Arearoadwaysystem

– Existing–withcurrentroadwayclassificationdesignation

– Future–IntermodalTransportationPlan(ITP)designation



• Trafficvolumesandconditions

– Ifpractical,allreportedcountsshouldbeactualcountsandnotbasedonfactoredpeakhoursampling.LatestavailablecountsfromtheCityand/orCDOTmaybeacceptableiftakenwithinareasonabletime(typically2years).

– PeakHourFactor(PHF)forexistingconditions.LOSanalysiscanmatchrecordedcounts

– Describeanyexistinghighaccidentlocationsinthestudyarea

• Transitservice

• Existingrelevanttransportationsystemmanagementand/orTrafficDemandManagement(TDM)programs(ifany)

• Otherasapplicable

3.0 ProposedDevelopment

% Descriptionofthesizeoftheparcel,generalterrainfeatures,andthelocation

% Vicinitymapshowingthesiteinrelationtothesurroundingtransportationsystem

% Siteplanshowingproposedproject

• Descriptionofeachproposedlanduseincludingtheunitsize(area,#ofworkers,etc.)

• Phasing(ifany)andconstructiontiming

% Sightdistanceexhibitsforproposedprojectaccesslocations

• SightdistanceshouldbebasedonspeedlineofsightasdescribedelsewhereinCityguidelines

• Ifverticalalignmentimpactssightdistance,thentheexhibitshouldincludeaverticalprofiledemonstratingthatverticalcurvesdonotinterferewiththeaccesslineofsight,orappropriatefielddata.

• Ifsightdistanceisnotanissue;explaintherationalewithinthetextofthereport.

4.0 ProjectedTraffic

% Sitetraffic

• Tripgenerationtable–ShouldfollowITE,TripGenerationguidelinesonwhentouseaverageratesandwhentouseequations.Thepeakhourofadjacentstreettrafficshouldbeusedwhenavailable.Also,includeITEorotherreferencematerialsintheappendixofthereportforanytripratesusedand/ortripreductionfactorsused.

• TripDistribution–Mayneedmultipletripdistributionsdependingonprojectphasingandtimingofsurroundingroadwaynetworkbuild-out

• Modalsplit(ifappropriate)

• Pass-bytrafficshouldnotexceed10%ofadjacentstreettrafficduringthepeakhour.

• Tripassignment

% Backgroundtraffic



• Openingyear(s)–UsecombinationoflatestPikesPeakAreaCouncilofGovernments(PPACG)model,otheradjacenttrafficstudies,existingcounts,NationalCooperativeHighwayResearchProgramReport(NCHRP)255methodology,andinterpolationtodetermine

• Horizonyear–NeedstomatchlatestPPACGtraveldemandmodelhorizonyear

% Totaltraffic

• Openingyear(s)–Sumofsitetrafficandbackgroundtraffic

• Horizonyear–Sameasabove

5.0 Trafficanalysis

% Existingconditions(withoutproject)–ifnotalreadypresentedinSection2.0

% Openingyear(s)

• Withoutproject

• Withproject

% Horizonyear

• Withoutproject

• Withproject

6.0 EquivalentSingleAxleLoads(ESAL)Projections

% Ifneededtoprovideadetailedpavementdesign,ESALprojectionsshouldbedevelopedusingthetechniqueprovidedintheCDOTPavementDesignManual

7.0 FindingsandconclusionswithPEcertificationandCitysignatureblocks.

% Siteaccess

% Accidenttrendsandcauses

% Trafficimpacts

% Parking–discussifproposedparkingmeetsCityrequirementsandifnot,howtheshortagewillbeaccommodated.Ifreciprocaland/orsharedparkingiscontemplated,aparkingaccumulationstudyforexistingfacilitiessimilartoproposeduseswillbenecessary.

8.0 Recommendations

% Siteaccess/circulationplan

% Improvements–AnadditionalLOSanalysistodemonstratethatproposedimprovementswillmitigatetheimpacts

• Canincludeaccessturnrestrictionsaswellasaccessspeedchangelanes.Ifspeedchangelanes(acceleration/decelerationlanesintoandoutofprojectaccesses)areproposed,depictgraphicallydemonstratinghowproposedspeedchangelaneconformstoCity’sguidelinesand/orqueuesproducedfromLOSanalysis(whicheverisgreater)

9.0 Appendix

% Inadditiontothetables/figuresshownintheattached“RequiredFiguresandTablesMatrix”whichcanbeincludedineithertheappendixorwithinthetextofthereport,thefollowingitemsneedtobeincludedintheappendixofthereport



• Trafficcounts

• Tripgenerationsources–eitherITEorotheracceptedsource

• Forecastcalculations/data

– IncludePPACGorothersourcedataandcalculationsonhowopeningyearandhorizonyearbackgroundforecastsweredetermined

• LOSAnalyses(forallscenariosstudied)

– Intersections

– Roadways

– Queues

– Weaves

• Parking

– Counts

– Calculations

Required Figures and Tables Matrix

Table or Figure Description

VicinityMapAreamapshowingsitelocationandareaofinfluence.Includeexistingroadwaysystemshowingmajorandminorstreetsadjacenttositeandsiteboundaries.

SiteDevelopmentPlan Planshowingtheproposeddevelopmentunderstudyincludingaccesslocations,buildingsizes,andlandusezones.

SiteLandUseTable Tabledescribingthedifferentsitelanduses,thedescribingunit(area,workers,etc…)andtheITEtripgenerationcode.

SiteTrafficGenerationTable

TableshowingtheestimateddailytripsandA.M.andP.M.peakhour(orweekend)tripsgeneratedbyeachcomponentoftheproposeddevelopment.Peakhourtripsmustbeshownseparatelyforinboundandoutbounddirections.ITELandUsecodeusedshouldbedisplayed.

InternalCaptureTable Tableshowingtripreductionsforinternalcaptureofamulti-usedevelopment.

Pass-byTripTableandFigure

Tableshowingthepass-bytripreductionandfigureshowingtheturningmovementsofthepass-byvehiclesenteringandexitingthesite.

TripDistributionandAssignmentFigure

Maportableshowing(bypercentages)theportionofsitetrafficapproachinganddepartingtheareaoneachroadway;maydifferbylandusewithinmulti-usedevelopment.

AverageDailyTrafficVolumeFigure Dailyvolumesonroadsinthestudyarea.



AMandPMPeakHourTurningVolumeFigure

Peakhourturningvolumesateachlocationcriticaltositeaccessorservingmajortrafficvolumesthroughthestudyarea.

LaneGeometryFigure Exhibitshowingtravellanesandmovementsateachlocationshownontheturningvolumefigure.

LevelofServiceFigure Levelsofservicecomputedforeachturningmovement,approach,intersectionandroadwayinthestudyarea.

QueueLength Scaleddrawingshowingqueuelengthsortablecomparingqueuelengthtostoragelengthandaccessspacing.

Note:Theabovetablesandgraphsmaybecombinedaslongastheinformationisunderstandable.



Appendix B

Standard Utility Locations

Thisappendix,whichwilldefinethestandardutilityandstormsewerplacementinthevariousstreetclassifications,isstillunderconsideration.



Appendix CRoundabout Design Guide

1.0 Introduction to Roundabout Design Guide

Roundaboutsareasafeandefficientformoftrafficcontrol,whichcanbeusedatmanyofthesamelocationsastrafficsignalsorstopcontrols.BasedonUSandinternationalstudies,roundaboutsreduceaccidentsformotorvehiclesandpedestriansand,duetotheslowerspeedsandthereducedangles,theseverityofaccidentsareless,withfewerinjuries.Becauseoftheadvantagesofroundabouts,itisthepolicyoftheCitytouseroundaboutsasasubstituteforothertypesofintersectioncontrol,includingintersectionswithnocontrol,2-wayorall-waystop.Theyshouldbeusedinsteadofatrafficsignalatalllocationswherearoundaboutisshowntooperateaswellorbetterthanasignalwherevertheroundaboutcanbeconstructedtomeetthesestandards.Roundaboutsareallowedonlocalstreets,minorandmajorcollectors,minorandprincipalarterials,butarelimitedtonomorethantwoapproachlanes.

Standardsincludedhereinwillbeused,alongwithengineeringjudgmentandinformationfromothersources,forthedesignofallroundaboutswithintheCityofColoradoSprings,andforthereviewofdesignsbycitystaffandprivateconsultants.Whereconflictingstandardsexist,thisdesignguideshallgovern.

Whendesigningroundabouts,thereareseveralcharacteristicsthatcanbestandardized,suchassigningandmarking;whileothersmustbeadaptedwithinthedesignstandardstofitthedemandsofthelocation,suchasapproachanglesandrightofwayrestrictions.Thisdesignguidehasbeencreatedtoallowengineerstheflexibilitytodesignaroundabouttofitaparticularsite,whilestillmaintainingconsistencywithotherroundaboutscitywidetoenhancedriverexpectancy.

Allroundaboutdesignswillrequireatwostepprocess:apreliminarydesigninitiallysubmittedthatmeetsdesigncriterialistedunderbothgeneraldesigncriteriaandspecific/geometricdesignelementsasnoted,anduponapprovaloftheoverallpreliminarydesign,afinaldesignshowingallconstructiondetailsandanyphasedconstructionsigningandmarking.



2.0 General Design Criteria

2.1 Appropriate Roadways / Locations

Roundaboutsshouldbeusedwherephysicalconditionssuchasapproachgradesandadequaterightofwayallow.Theyarelimitedtouseonaroadwaywithfourorfewerthroughlanesresultinginnomorethantwoapproachlanes.Theyarenotappropriatewhenthecapacityrequiresmorethantwocirculatinglanes.Roundaboutsarealsonotappropriateiftheuseofaroundaboutisexpectedtoproducegreatervehicledelayorincreaseddifficultyforpedestrians.

Designoftheapproachroadandroundaboutmustprovideadequatevisibilityoftheroundaboutfromadistancethatwillallowapproachingdriverstoseetheroundabout,bothdaytimeandnighttime.Thisdecisionsightdistance(DSD)istheminimumdistancerequiredthatwhichwillallowdecelerationfromthe85%travelspeed(orpostedspeedlimit,whicheverisgreater)tothemaximumentryspeedof20MPH(singlelane)or25MPH(multilane)withoutexceedingadecelerationrateof10’/s/s.Thisisgenerallythesamedistanceasthe“intersectionsightdistance”notedinAASHTOstandards,variablebyapproachspeed.

2.2 Approach and Circulatory Speeds

Thecenterlinesoftheapproachingroadwaysshouldgenerallymeetnearthecenteroftheroundabout,withsomeoffsetallowedaslongasthefastestpathcriteriaaremet.However,roundaboutsoffsetsignificantlyfromthiscriteriawillcreateadifficultdesign,withthefastestpathrequiringartificialrestrictionsordifficulttotraverseapproaches.Thiscanresultinvehiclescrossinglanesand/orfailingtofollowthelanelinesontheapproachorexit.Roundaboutsmayhavethree,fourorfiveapproaches.Approachroadwaysmaybesinglelane,singlelanewithaflareouttoprovideanaddedlaneatthecirculatingroadway(usedtoprovidealeft-onlylane),singlelanewithaby-passrightturnlane,ortwolaneswithoutaddedlane.Theconfigurationisbasedontheturningmovementvolumes.

Theapproachroadwaysectionincludestheroadwayfromthepointwheretrafficistravelingatthespeedlimittotheyieldpointwheretheenteringvehiclesentertheinscribedcircle(seefigureIforexplanationoftheroundaboutelements).Thissectionextendstothelimitsofthedecisionsightdistance(Exhibit3-3,Section3AASHTOGeometricDesignofHighways&Streets,2001,avoidancemaneuverB–Stoponurbanroadway).

Thecentralislandshallbevisiblefromtheintersectiondecisionsightdistancebothdayandnightwithouttheinstallationofanylightingthatwoulddistractorshinedirectlyatanyvehicleoperators.Theminimumdistancevarieswiththeroadwayclassification,butgenerallyisthesameasapproachinganyotherintersectionlistedintheintersectionstandards.Thedistancewherethedrivershouldbeabletotelltheyareapproachingaroundaboutrangesfrom450’priortotheyieldpointforalocalroadwayto750’forahigherspeedarterial.



Approachspeedscalculatedat50’and150’priortotheyieldpointorentrancetothecirculatingroadwayarecriticaltothesafeoperationoftheroundabout.Thedesignshouldmeetthemaximumdesirableapproachspeedof20MPH(singlelane)or25MPH(multilane)at50’,and5MPHfasterthanentryspeedatthe150’point.Actualoperatingspeedmaximumsarecontrolledbythe“fastestpath”asnotedinFigureII,whicharetheradiimeasuredalongthevehiclepath,notalongthecurbflowlines.Reversecurves,landscaping,roadwaynarrowing,andotherformsofpsychologicalspeedreductionmayberequiredwhereapproachspeedsarehigh.

DesignspeedlimitationsandtheirrespectiveradiithroughtheroundaboutareshownonFigureII,includedinSection3.0–Specific/GeometricDesignElements,identifiedasR1,R2,R3,R4,andR5.Themaximumradiusandrespectivespeedsatvariouslocationsonthetravelpaththroughtheroundaboutarecriticaltothesafeoperationoftheroundabout.Curbandgutter,splitterislands,andthecentralislandplacementcontrolthefastestvehiclepath,butarenotthesameradii.Inadditiontotheoverallspeedlimitationforoperation,themaximumspeeddifferentialbetweenanytwopartsofthetraveledpathis12MPHtoreducethepotentialforrear-endaccidentsforvehiclesturningleftorexiting.

Allalignmentparameters,includingsightdistancerestrictionsforlandscapingshallbeincludedinthepreliminarydesigndrawings.SeeFigureIIIforsightdistancerestrictions.

2.3 Design Vehicle

Allroundaboutsshallbedesignedtoallowsinglepassengercars,pickups,SUtrucksandcitybusoperationwithouttheuseofatruckapron.Largertruckswillrequiretheuseofatruckapron,especiallyonsinglelaneroundabouts.Amovingvan,firetruck,and/orWB50truckshallbeusedtocheckfortheabilitytonavigatetheroundaboutusingtruckaprons,butwithoutstrikinganyoftheoutsidecurbs,signs,utilitystructures,orsplitterislands.

Operationofallroundaboutsshallbecheckedusingtheturningcharacteristicsforthedesignvehiclesinthefollowingchart,exceptforstatehighways,orarterialsnearindustrialareas,otherareasofhightruckusage,oralongestablishedtruckroutes,whereaWB67truckshallapply.Theturningtrucksmayberequiredtouseatruckapronmeetingthesestandards,butwithoutcausinganydamagetoanypartoftheroundabout.Generally,amultilaneroundaboutwillnotneedatruckapron,aslargervehicleswillusebothlanes.

Road Classification Circulatory Lanes Design Vehicle Roundabout Type

Local 1 SU Singlelane

Collector 1 WB40 Singlelane

MinorArterial 1 WB50 Singlelane

MinorArterial 2 WB50 Multilane

MajorArterial 2 WB50 Multilane

Areasnotedabove,regardlessofclass 1-2 WB67 Singleormultilane



Theuseofeithervehicleturningtemplates,orplotfromAutoturnsoftwareisallowed.Allpreliminarydesigndrawingsmustincludethisturningpath.

2.4 Pedestrian/Bicycles

Allroundaboutsshallbedesignedtoallowpedestriancrossingswheneversidewalksareexistingorplannedattheintersection.Pedestriancrossingsshallbemarkedandsignedwhenever20yearprojectedpedestrianusageisequaltoorexceeds20pedestriansperhouratanytimeoftheday.Markedandsignedcrosswalksarealsorequiredforallroundaboutcrossingsonaschoolrouteorborderingapark,shoppingarea,orotherareawherepedestrianactivityisexpected.Lightingshallbedesignedtoilluminatethepedestrianareawithoutbacklightingpersonswithinthecrosswalk.

Inareasofunusuallyhighpedestrianusage,supplementalactivewarningdevicesmayberequired,suchasflashingbeaconsorLEDsupplementedsignage.Thewarningdevicesmaybeactivatedeithermanuallybytheuserorautomaticallybyanyapproveddetection/actuationtechnology.Whereblindpedestriansareexpected,theflashingbeaconsmustbeactivatedmanuallybytheuseofatactileorsoundemittingpushbutton.

Iftheroundaboutisonastreetwithbicyclelanesoraroadwaywithdesignatedorplannedbicyclelanes,theapproachshallallowfortheconnectionfromthebicyclelanetothesidewalk,allowingthebicyclistthechoicetoeither“claimthelane”andproceedthroughtheroundaboutasavehicle,orexittheroadwaypriortotheroundaboutontothesidewalkandusethepedestrianfacilities.Theroadwayshouldbereducedinwidthatthepointwherethebicyclelaneexitsfromtheroadway.

SeeFigureIVfordetailsofconstruction,signingandmarkingforpedestriansandbicyclists.Detailsofmarkingandsigningshallbeincludedinthefinaldesign.

2.5 Design Software

Theappropriatedesignsoftwareshallbeusedtoensureproperdesignandcapacity.Localstreetorminorcollectorintersections,wheretheroundaboutisusedforaestheticsorspeedcontrol,andvolumesarelowdonotrequireacapacityanalysis.OtherclassificationsmayrequiresomeanalysisbyeitherAASidraorRodeltoanalyzetheroundaboutincomparisonwithothertrafficcontroldevices.Forcapacityanalysisordesignvariablesonmajorcollectors,minororprincipalarterials,theuseofRodelsoftwareisrequired.

AllpreliminarydesignsshallbeaccompaniedbyAMandPMpeakhourturningmovecountsforexisting(ordevelopmentopening)volumesandfora20yearprojection,includingtheelectronicfilefromRodelwhenrequired.Wheretheroundaboutisnearaschool,shoppingcenter,orothermajortrafficgenerator,thepeakhourforlocaltrafficwiththetrafficgeneratorfullydevelopedshallbeused.



2.6 Utilities & Drainage

Designofundergroundandoverheadutilitiesshallbeincludedonthefinaldesign.Designofwater,sewer,electric,andgaslinesshallmeettheappropriateColoradoSpringsUtility(CSU)standards.StreetlightingshallfollowCSUstandardsforpole,lightfixture,andtypeoflighting.Lightingshallbedesignedtoilluminateanypedestrianswithinthecrosswalkswithoutcausingabacklighteffect.Lightingshallbesituatedtohelpthedriveridentifythegeneralshapeoftheintersectionandtohighlightconflictpointsorareasofentry,andexitfrombeyondthestoppingsightdistanceasidentifiedinFigureIII.

Thefollowingdrainagestandardsapplytoroundabouts:

1. DrainageshallcomplywiththeCityDrainageCriteriaManual.Roundaboutsshouldbegenerallydesignedtoslopeawayfromthecentralislandwithdrainageinletslocatedontheoutercurbline.Placementofanyinletsshallincludeconsiderationofthewheelpathtravelingthroughtheroundaboutwiththedesirablelocationbetweentheentranceandexit,notalongtheroundaboutentrance,thecentralisland,theexit,orthesplitterislands.Inletswithintheroundaboutshallbeconstructedwitha6inchcurbheightandnoextensionofthegutterpan.AnalternatetothestandardCityinletdesign,suchastheCDOTTypeRinlet,isallowedtomeetthiscriterion.

2. If the8inchcurbheightisusedwiththestandardCityinletdesign,theinletmustbelocatedoutsideoftheroundaboutandapproachestolimitinfluenceonthedrivers’paththroughtheroundabout.Allinletguttersectionswillbelimitedinwidthto24inchesfromliptoflowline.

2.7 Landscaping

Landscapingisanimportantpartofthedesign,especiallyinthecenterislandtoprovidevisualawarenessoftheroundabout.Landscapingdesignsmustconsiderpedestrianandvehiclesafety,providingyeararoundamenitiesfortheroundaboutuserswithoutcausinganysightdistanceproblems,especiallyonapproachtopedestriancrossings.

Allfinaldesignsshallincludealandscapingdesignsheetidentifyingplanttypes,heightfromthetopofthematureplanttotheroadwaysurface,includingtheheightofplanterarea,andminimumpruningheightforthelowerbranchesofanytreestobeplanted.SeeFigureIIforareaswhereheightisrestrictedforsightdistancereasons.Withinthecentralisland,outsideoftherequiredstoppingsightdistanceline,theuseoflargermaterialsisencouragedtoimprovethedriver’sperceptionoftheroundaboutlocationandshape.Avoiddistractingdisplays,suchassigns,intricatesculpturesoranimateditemsorglarefromlightsthatcouldincreasethepotentialforaccidents.

2.8 Other

Otherdesigncriteriainclude,butarenotlimitedto:

1. The exitoftheroundaboutshouldbenosmallerthantheentryandincludetransitiontothefullwidthcross-section,includinganyon-streetparking.



2. Transitstopsshouldbelocateddownstreamoftheroundaboutclearoftheexitarea,andbuiltwithapullout,ortheymaybecombinedwiththeon-streetparkingarea.

3. Priortosubmittingthepreliminarydesign,apre-designmeetingisrecommendedwithCityEngineeringtoidentifyanyunusualorlocation-specificdesigncriteriaordesignelementsorotherissuesuniquetothelocation.



3.0 Specific/ Geometric Design Elements

3.1 Approach Roadway

Theapproachroadwaydesignelementsincludecurbalignment,medianwidthandtransition,approachflare,crosswalklocation,horizontalandverticalalignmentoftheapproachlane(s),intersectionandstoppingsightdistancecalculations,approachspeed,fastestpathradii,andotherassociatedelementsidentifiedinFiguresIthruVI.

Minimum/maximumstandardsincludethefollowing:

Fastest PathSingle Lane Multilane Roundabout

R Max Speed (MPH) R Max Speed (MPH)

R1 Entry 86-99’ 20 152-178’ 25

R2 Circulating 99-116’ 20 178-210’ 25

R3 Exit 152-178’ 25 152-178’ 25

R4 Leftturn 99-116’ 15 178-210’ 25

R4 Minimum* 18-20’ 10 33-37’ 13

R5 Rightturn 152-178’ 20 152-178’ 25

*R4hasaminimumrequirementtoreducerearendaccidentscausedbyexcessivespeeddifferential

Note–radiiaregivenasarangeforvarioussuperelevationratesfrom0%to4%,positiveforR1,R3&R5,andnegativeforR2andR4.

CalculationsforeachspecificroadwaysegmentandcorrespondingcrossslopeshouldfollowAASHTOGeometricDesignofHighways&Streets,2001orlater

Maximumapproachgrade 2%for200’onminorandprincipalarterials4%for100’onminorandmajorcollectors4%for50’onlocalstreets

ApproachDecisionSightDistance(“DSD”onfigureWW)

375’for25MPHorless450’for30MPH525’for35MPH600’for40MPH675’for45MPH750’for50MPH

Note–ApproachDecisionSightDistance,DSD,isthedistanceatwhichthedriverisawareofthechangeinalignmentcausedspecificallybytheroundabout.IftherequiredDSDisnotavailableduetotopographiclimitations,advancewarningsignswillberequired.VerticalalignmentmustbecheckedaswellashorizontalalignmentforrestrictionstoDSD.



MinimumApproachTangent(approachcenterlinetoyieldline)

300’onprincipalarterial200’onminorarterial100’onallcollectors50’onlocalaccess

Min.distancetonearestaccess(distancefromsplitterisland)

600’onprincipalarterial300’onminorarterial100’onallcollectors30’onlocalaccess

3.2 Circulating Roadway

Thecirculatingroadway,thatportionoftheroundaboutbetweenthecentralislandandtheinscribedcircleistheportionoftheroadwayusedbyvehiculartraffic.Theinscribedcircleoftheroundabout,whichenclosesthecirculatingroadway,shallbelargeenoughtoaccommodateallroaduserswithoutexceedingthefastestpathmaximumradii.Generally,thedesignoftheinscribedcirclewillbefrom130’to200’formultilaneroundabouts,andfrom80’to130’forsinglelaneroundabouts.Theoutsideedgeofthecirculatingroadwayiswithinandgenerallythesamesizeastheinscribedcircle.

Thecirculatingroadwayshallbefrom1.0to1.2timestheapproachroadwaywidthattheentrytotheroundabout.Super-elevationforthecirculatoryroadshouldgenerallybenogreaterthan-0.02,althoughasuper-elevationofupto-0.04maybeapprovedifconditionswarrant.Adversesuperelevationispreferredforthecirculatoryroadasitprovidesasmoothertransitionformotorists,betterdrainage,andhelpskeepspeedstoanacceptablelevel.

Roundaboutsmaybedesignedandbuiltinstages,withtheinitialsizeoftheinscribedcirclelargeenoughforamultilaneroundabout,withanoversizedcentralislandthatrestrictsthecirculatingroadwaytoonelane.Inthiscase,itislikelythatatruckapronwillbeneeded.

Bypasslanesshouldbeavoidedifpossible,duetothedifficultyforpedestrians(especiallysightimpaired)tosafelycrossthreeroadwaysinsteadoftheusualtwoinotherroundabouts.IfthecapacityanalysiswithRodelindicatesthattheexistingandshorterrangeprojectedvolumeswilloperateatlevelDorbetter,theroundaboutshouldbebuiltwithoutabypass.Ifthe20yearprojectedvolumesshowtheneedforabypass,adequaterightofwayshallbeincludedtoaccommodatethefutureexpansionandthebypasswillbebuiltwhentheoperatingLOSexceedslevelC.

3.3 Sight Distance

StoppingSightDistance(SSD)isthedistancebetweenthehazardandtheapproachingdriver,measuredalongthevehiclepath.Itisusedtoassesssafetyforvehicletovehicleandvehicletopedestrianorbicyclehazards.Everyconflictpointattheintersectionmustbechecked,basedonvehiclespeedneartheconflictareaforobstructionsoftherequiredvisibilityarea–seeFigureIII.



SSDfortheapproachandyieldattheroundaboutarebasedonAASHTOstandardsforurbanroadways,Section9ofthe2001geometricdesignmanual,CaseAforsightdistancetotheleft,andSection3,Ex3-1forSSDrelatingtopedestrians.Horizontalandverticalalignmentmustbechecked.

StoppingSightDistance 15MPH80’ 20MPH 115 25MPH 155 30MPH 200 35MPH 250 40MPH 305 45MPH 360

3.4 Splitter Islands

Splitterislandsprovideproperdeflectionofvehiculartrafficforspeedcontrolandpedestrianrefugearea.Theyarerequiredonallroundabouts,withpaintonlyallowedasanoptiononmini-roundaboutsand6”highmountablecurbonallotherroundabouts.Theyshallbeaminimumof50’long(measuredfromtheoutsideedgeofthecirculatorroad)ifthereisapedestriancrossing.Thealignmentofthesplitterislandshouldincorporateatangentextensionofthesplitterislandflowlinemeetingtheoutsideflowlineofthecentralisland.SeeFigureV

Splitterislandswherecrosswalksexistorareprojectedshallhaveaminimum6’x6’pedestrianrefuge(an8’x8’refugeispreferable).Crosswalksshouldbe25’fromtheyieldlineforsinglelaneroundabouts,and45–50’formultilaneroundabouts.Onmultilaneapproaches,thecrosswalksshouldberadialtothetraveledwaytoimprovevisibilityforpedestrians.

Thecurbfacealongthecirculatingroadwayshouldbeoffsetfromthetraveledwayadistanceof3’ontheapproachsidenexttothecirculatingroadwaytaperingto1.5’attheintersectionoftheentryandtheapproach.IslandnoseradiishallmeetthedimensionsasshowninFigureV.

3.5 Central Island

Centralislandsarethemostvisiblepartoftheroundaboutforapproachingvehiclesandestablishtheshapeandsizeoftheroundabout.Theirsizeiscriticaltothecorrectoperationoftheroundabout.

Centralislanddiameterforamultilaneroundaboutshouldbedesignedforeachcasetoassurethatthedeflectionforenteringvehiclesresultsinmeetingthemaximumfastestpathrequirements.Generally,thecentralislanddiameterwillbebetween65’and135’foramultilaneroundaboutandbetween50’and100’forasinglelaneroundabout.

Requiredtruckapronsshallnotexceed-0.08superelevations.Theyshallbeconstructedwitha4”highmountablecurbslopedbackata60degreeangleandroundedatthetop,with12”spillgutterfornewroundabouts.Key-incurbonlywithoutgutterpanwillbeallowedforretrofitofexistingintersectionsforthecentralislandwithdrainageawayfromthecurb.



Truckapronsshouldbeconstructedofconcrete,contrastingintextureandcolorfromtheroad,easytomaintain,andabletowithstandloadsofturningtrucks(i.e.minimum6”decorative,contrastingconcrete,suchasexposedaggregate,colored,and/orpatternedconcrete,etc.).Brick,cobblestone,orotherindividuallyplacedpavingmaterialsarenotallowed.

Elevationdrawingsofthecentralislandshallbeincludedwiththepreliminaryplansforreview.Thecentralisland,notincludinganytruckapron,shallbeaminimumof2’abovethesurroundingroadwayoutsideofthesightdistancerestrictedareas,andshallbeofcontrastingtextureandcolorstotheroadwayandthebackground.Theyshallbedesignedforlowmaintenance(restricttheuseofsodorotherhighmaintenancesurfaces).

3.6 Signing and Marking 1. Signing-SeeFigureIVforsignlocations.AllsignsshallconformtoManualonUniform

TrafficControlDevices(MUTCD)asmodifiedbythelatestrecommendedroundaboutsigningstandardsandbythesedesignstandards.

a. Advanceroundaboutwarningsignswithadvisoryspeedplaquesarerequiredwhenevertopographyordriverdistractionprecludesadequateadvancevisibilityoftheroundabout–seeApproachDecisionSightDistanceinparagraph3.1fordistances.Theymayalsobeusedtemporarilyorpermanentlywheneveraroundaboutismodifiedoranewroundaboutconstructedasaretrofittoanexistingintersection.

b. Yieldsignsshallbeplacedontherightsideoftheroadatthepointwherevehiclesaretoyieldwhenenteringtheroundabout.Supplementalyieldsigninginthesplitterislandmayberequiredduetoalignmentorsightdistanceproblemswhereasingleyieldisnotadequate.Supplementalsignsnoting“ToTrafficinCircle”mayberequiredtobeaddedtotheyieldsignsonmultilaneroundabouts.“YIELD”pavementmarkingmayberequiredwherefieldobservationwarrants.

c. Laneassignmentsignsdepictingthelanesmaneuveringaroundtheroundabout(asinthefollowingfigure)shallbeprovidedonallmulti-laneapproaches.

1. Note–thissigntobereplacedwiththenewsignwith“Roundabout”atthetopinBlack/Yellow,and“LeftLane”and“RightLane”belowthesymbols.Also,examplesofsignswithonlyoneturnata“T”intersectionwillbegiven,andasignforasinglelaneentrywithanauxiliaryleftturnlaneontheflaredapproach.

d. Streetnamesignswithaminimumof6”letteringshallbeplacedonthesplitterislandsorientedtowardtrafficonthecirculatoryroadway.Flagtypesignsindicatingtheexitstreetnamearerequiredforarterialsonanymultilaneroundabout.

e. Advanceddirectionalguidancesigns(asdepictedinthefollowingfigure)shallbeusedasnotedintheintersectionguidelines.



f. Seeparagraph2.4forrequiredpedestriancrossings.Pedestriansignageisrequiredwherepedestrianusagemeetsminimumrequirements.Allmarking,signing,andsupplementalwarningdevicesshallmeetMUTCDstandardsasmodifiedandshowninthedetaildrawingsinthisdesignguide.

2. Marking-AllpavementmarkingsshallconformtoMUTCDasmodifiedbythelatestrecommendedroundaboutguidelinesandthesedesignstandards.

a. Laneusepavementmarkings,includingarrowsandsolidordashedlinesshallbeusedonallmultilaneroundabouts.SeeFigureIVfortheircorrectplacement.

b. Yieldtrianglesshallbeusedtomarkthelocationatwhichdriversmustyieldtocirculatingtraffic.Theyieldmarkingsshallbecurvedalongtheoutlineofthecirculatoryroadandshallhavetrianglesorientedtowardapproachingdriversasdepictedinthefollowingfigure.Supplemental“YIELD”pavementmarkingmayberequiredwherefieldobservationsindicateasignificantnumberofvehiclesdonotyield.

c. Yellowedgelinesshallbeplacedalongtheleftedgeoftheapproachroadwayalongtheedgeofthesplitterislandsifthesplitterislandisinstalledwithinapaintedmedian.Formultilaneroundaboutsonly,yellowedgelinesarerequiredaroundthecentralisland,andwhiteedgelinesarerequiredalongtherightsideofthesplitterislandoutliningthecirculatingroadway.

d. Pedestriancrossingsshouldbemarkedwithladderstylemarkingsconsistingof2’x8’markings.

e. Retroreflectiveraisedpavementmarkers(RRPM)mayberequiredonthecentralislandandsplitterislandswheresightdistanceand/orlightingindicatesimprovedwarningisneededfornighttimeoperation.

3.7 Landscaping Design Elements

Splitterislandsshallbehardscapeorcontainlowlevelvegetationwithamaximumheightofthecurb,splitterislandstructure,andlandscaping,atmaturity,of30”abovetheroadway(seeFigureIII).

Thecentralislandshouldcontainverticalfeaturesoutsideofthestoppingsightdistancerestrictionarea,visibletoapproachingtrafficbothdayandnight,toreduceapproachspeeds.

NewroundaboutswithlandscapingshallhaveamaintenanceagreementwiththeCityParksDepartment,providingformaintenance,ortheyshallhaveguaranteedfundingformaintenanceofthelandscapingbyprivateorganizations(i.e.homeownersassociations,propertymanagementagencies,etc.).Retrofitroundaboutsshallhavelow-maintenancelandscapingoramaintenanceagreementsimilartonewroundabouts.

Landscapinganddesignelementsshallbeaestheticallypleasing,shallfitwithinthecontextofthesurroundingarea,shallnotdistractdrivers,andshallnotinterferewithpedestriansafety.





9



10



11



12



13



14



15



16



4.0 Definitions

Central Island–theraisedareainthecenterofaroundaboutaroundwhichtrafficcirculates

Fastest Path Radius–theminimumradiusonthefastestthroughpatharoundthecentralislandmeasured5’fromanyflowline

Circulating Volume–thetotalvolumeinagivenperiodoftimeonthecirculatoryroadwayimmediatelypriortoanexit

Circulatory Roadway Width–thewidthbetweentheouterflowlineofthecirculatoryroadwayandthecentralisland,notincludingthewidthofanyapron

Deflection–thechangeintrajectoryofavehicleimposedbygeometricfeaturesoftheroadway

Departure Width–thewidthoftheroadwayusedbydepartingtrafficdownstreamoftheroundabout.Thedeparturewidthistypicallynomorethanthetotalroadwaywidth

Decision Sight Distance–fromAASHTOGeometricDesignmanual,Section3,thedistancefromtheintersectionwherethedriverrecognizesthattheyareapproachinganobstaclethatwillrequireamaneuverorstop

Design Vehicle–thelargestvehiclethatcanreasonablybeanticipatedtouseafacility

Entry Flare–thewideningofanapproachtoprovideadditionalcapacityattheyieldlineandstorage

Entry Path Radius–theminimumradiusonthefastestthroughpathpriortotheyieldline,measured5’fromanyflowline,notedasR1

Entry Radius–theminimumradiusofcurvatureoftheoutsideorrightcurbattheentry

Entry Speed–thespeedavehicleistravelingatasitcrossestheyieldline

Entry Width–thewidthoftheentrywhereitmeetstheinscribedcircle,measuredperpendicularlyfromtherightedgeoftheentrytotheintersectionpointoftheleftedgelineandtheinscribedcircle

Exit Path Radius–theminimumradiusonthefastestthroughpathintotheexit,measured5’fromanyflowline,notedasR3

Exit Radius–theminimumradiusofcurvatureoftheoutsiderightcurbattheexit

Exit Width–thewidthoftheexitwhereitmeetstheinscribedcircle,measuredperpendicularlyfromtherightedgeoftheexittotheintersectionpointoftheleftedgelineandtheinscribedcircle



Inscribed Circle–thecircleformingtheouteredgeofthecirculatoryroadwayusedtodefinethesizeofaroundabout,measuredbetweentheouteredgesofthecirculatingroadway.Itisthediameterofthelargestcirclethatcanbeinscribedwithintheoutlineoftheintersection

Multilane Roundabout–aroundaboutthathasatleastoneentrywithtwoormorelanes,andacirculatoryroadwaythatcanaccommodatemorethanonevehicletravelingside-by-side

Right-Turn Bypass Lane–alaneprovidedadjacentto,butseparatedfrom,thecirculatoryroadway,thatallowsright-turningmovementstobypasstheroundabout.Alsoknownasaright-turnsliplane

Roundabout–anintersectionwith3ormoreapproachlegs,generallycircularinshapewherecontinuousflowoftrafficisallowedthroughtheuseoftheyieldandmergemaneuvers

Sight Triangle–anarearequiredtobefreeofobstructionstoenablevisibilitybetweenconflictingmovements

Single-Lane Roundabout–aroundaboutthathassinglelanesonallentriesandonecirculatorylane

Splitter Island–araisedorpaintedareaonanapproachusedtoseparateenteringfromexitingtraffic,deflectandslowenteringtraffic,andprovidestoragespaceforpedestrianscrossingthatintersectionapproachintwostages

Stopping Sight Distance–thedistancemeasuredalongthecenterlineoftravelonaroadwayrequiredforadriverusingthesighttriangleorsightlinetoperceiveandreacttoanobjectintheroadwayandtobraketoacompletestopbeforereachingthatobject

Truck Apron–araised,coloredand/ortexturedconcretesurfacenexttotheoutsidecurbofthecentralislanddesignedtoallowlargetruckstoturnwiththeirrearwheelsleavingtheroadwayandridingupontotheapronarea

Two-Stage Crossing–aprocessinwhichpedestrianscrossaroadwaybycrossingonedirectionoftrafficatatime,waitinginapedestrianrefugebetweenthetwotrafficstreamsifnecessarybeforecompletingthecrossing

Date post:	17-Apr-2018
Category:	Documents
Upload:	dinhkhanh
View:	223 times
Download:	0 times

Traffic Criteria Manual - Colorado Springs · Page 6 Traffic Criteria Manual ENGINEERING CRITERIA...

Documents