John N. LaPlante, P.E., P.T.O.E. T.Y. Lin International Prepared for the: Annual Meeting of the...

transcript

John N. LaPlante, P.E., P.T.O.E. T.Y. Lin International

Prepared for the:Annual Meeting of the AASHTO

Highways Subcommittee on Design

July 15, 2008

Complete Streets: Basic Design Considerations

What is a Complete Street?

A Complete Street is safe, comfortable and convenient for

travel via automobile, foot, bicycle, and transit.

An incomplete street:

Too narrow for comfortable 'sharing'

Uninviting for transit riders

Room for vehicles, but no room for people

We know how to build right

• AASHTO Ped Guide published in October 2004.

• Included many new and innovative concepts.

• Reiterated some often overlooked AASHTO Green Book guidelines.

AASHTO Ped Guide

AASHTO Green Book encourages roadway designers to provide for peds. “Interactions of pedestrians with traffic are a major consideration in highway planning and design.”

Current Green Book

Safety is a key consideration. Peds are the most vulnerable of all roadway users.

AASHTO Ped Guide

Accessibility is also key. Ped facilities should accommodate peds of all abilities.

AASHTO Ped Guide

Basic Design Elements

• Sidewalks• Crossing the street • Medians and islands• Traffic signals• Crosswalks• Crosswalk markings• Curb extensions• Transit• Bicycles

Sidewalks

Not after space for future sidewalks is all gone

AASHTO Ped GuideSidewalk Design

Sidewalk Design

“All roadways along which pedestrians are not prohibited should include an area where occasional pedestrians can safely walk.”

– Unpaved walkway– Shoulders in rural areas– Sidewalks in urban areas

Locations with no sidewalks are twice as likely to have vehicle-pedestrian crashes than sites with sidewalks.

AASHTO Ped Guide

Pedestrians can get by without sidewalks on Pedestrians can get by without sidewalks on quiet streetsquiet streets

Ashland OR

Shoulders serve pedestrians in rural areasShoulders serve pedestrians in rural areas

Benton County OR

At a certain point, sidewalks are neededAt a certain point, sidewalks are needed

Canyonville OR

““Goat trail” indicates sidewalks are neededGoat trail” indicates sidewalks are needed

Jefferson Parish

Set triggers for future sidewalks• Development densities

• Developer requirements

• Going from open to closed drainage

AASHTO Ped GuideSidewalk Design

The AASHTO “Green Book” states:

“Sidewalks are integral parts of city streets”

Sidewalks are not added to streets, Sidewalks are not added to streets, they are they are part of the streetpart of the street

Fredericksburg VA

Forcing pedestrian Forcing pedestrian into streetinto street

Sidewalks should Sidewalks should not end midblocknot end midblock

Sidewalk DesignSidewalks on only one side of the street?

– Weakens pedestrian safety by requiring unnecessary street crossings

– Lacks connectivity– Generally not recommended

AASHTO Ped Guide

Mountable curbs are not appropriate on local streetsMountable curbs are not appropriate on local streets

Casper WY

Separated sidewalk is uncluttered,Separated sidewalk is uncluttered, pleasant pleasant to walk onto walk on

Reno NV

Parkway separation makes it easy to meet Parkway separation makes it easy to meet ADA at drivewaysADA at driveways

Salem OR

Narrow curbside sidewalks are inadequate in Narrow curbside sidewalks are inadequate in commercial areas commercial areas

Reno NV

Crossing the Street

Pedestrians shouldn’t be terrified crossing the streetPedestrians shouldn’t be terrified crossing the street

Santa Ana CA

Pedestrians want & need to cross the street safely

High speeds lead to greater chance of serious injury & death

Speed Matters

Child dart-out: speed is a factor!

150’

First scenario: Speed 25 MPH

100’

100’ = distance covered in 2.5 sec. perception/reaction time

150’

Driver applies brakes

First scenario: Speed 25 MPHDriver applies

brakes

100’

150’

50’ stopping distance (wet pavement)

First scenario: Speed 25 MPH

Result: Nothing happens beyond one scared child, driver & parent!

100’

150’

Second scenario: Speed 38MPH

140’

140’ = distance covered in 2.5 sec. perception/reaction time

150’

140’

150’

140’

150’

In the last 10’ car slows to 36 MPH

150’

Result: a high speed crash

Where do these two scenarios lie on the pedestrian fatality risk scale?

Second scenario: Crash speed 36 MPH

First scenario: no crash

Complete Streets Design Controls

• Complete Streets design begins with

Target Speed:– Desirable operating speed– Mobility for motor vehicles – Safety for pedestrians and bicyclists– Usually posted speed limit

Conventional design Conventional design criteria primarily based criteria primarily based on:on:

Functional classFunctional class

Design SpeedDesign Speed

Defining Mobility

• Typical experience:– 45 mph speed– 2 min wait at signal

Defining Mobility

• Viable alternative:– 2-way progression set for 30 mph

Benefit/Cost Analysis

• Reducing speed from 45 mph to 30 mph– For a 5-mile trip, a 3.33-minute delay– Assume 30,000 ADT and $20/hr driver cost– $12.154 million in loss to economy, right?

• Wrong!– Delay for each person is still 3.33 minutes– Less time than their daily stop for Starbucks

• Community benefit– Slower operating speeds– Safer and more comfortable ped crossings

Roadway Capacity Analysis• Design urban roadways to LOS D

• Designing to LOS C for peak hour means:– Unnecessary pavement, waste of tax dollars– Increased ped crossing times, thus reducing

vehicular movement times– Increased operating speeds for other 22 hours

Medians and IslandsReduce crashes by 40%

Basic Principle Break long complex crossing into two simpler crossings

Corvallis OR

Poor sign placementPoor sign placement

Choosing location for island: must have O & D

Corvallis OR

In this case, apartments across from bus stop and stores

Place cut-through at an angle…

Flush median is not much of a refugeFlush median is not much of a refuge

Crystal City VA

Flush median is not much of a refugeFlush median is not much of a refuge

Atlanta GA

Replace with a raised islandReplace with a raised island

Atlanta GA

Intersection Design

Small, tight intersections best for pedestrians…Simple, few conflicts, slow speeds

Intersection Design – Curb Radii

– Actual curb radius (R1)

– Effective radius (R2)

AASHTO Ped Guide

Keeping it tight: Curb radii

* Impossible move on one-way street

Intersection geometry:

Large radius increases crossing distance, and affects crosswalk & ramp placement

Effect of large radius on crosswalk

Additional area to crossAdditional area to cross+ Higher speed turns+ Higher speed turns

It’s more than the distance…

Effect of large radius on crosswalk

Hard to figure out where to crossHard to figure out where to cross

Effect of large radius on driversEffect of large radius on drivers

They drive fast…They drive fast…

… … ignoring pedestriansignoring pedestrians

Intersection Design – Curb Radii

AASHTO Ped Guide

• Use entire available width to turn into

• Select appropriate design vehicle

Must consider design vehicles, but don’t choose Must consider design vehicles, but don’t choose larger vehicle than necessarylarger vehicle than necessary

We shouldn’t design for the exceptional vehicleWe shouldn’t design for the exceptional vehicle

Raised islands at intersection separate conflicts

Right-Turn Slip Lane: Design for pedestrians

High speed, head turner low visibility of pedestrians

Wide Angle

Old Way

55 to 60 degree angle between vehicle flows

New proposal

Slower vehicle speeds, good visibility of pedestrians

Tighter angle

Island with fairly good geometry

Free Flow Turn Lanes

Prevent pedestrian movements

Expressway Ramps

• Right angle intersection where ramp meets cross street

• Design urban exits for 20 mph

Signal timing & other simple Signal timing & other simple innovative ideas to minimize innovative ideas to minimize

pedestrian delay & conflictspedestrian delay & conflicts

Traffic Signals

Use short signal cycle lengthUse short signal cycle length

Long wait Long wait causes stacking: peds wait in street,auses stacking: peds wait in street,or don’t wait and cross against the signalor don’t wait and cross against the signal

Portland OR

Set pedestrian signal to recall to “Walk”

when major street is set to recall to green

Peds should not be required to push a button

1.1. WALKWALK

2.2. Flashing DON’T WALK *Flashing DON’T WALK *

3.3. Steady DON’T WALKSteady DON’T WALK

1/2 of Americans don’t understand 1/2 of Americans don’t understand it;it;

Is there a better system?Is there a better system?

Current system:Current system:

* Flashing red hand/don’t * Flashing red hand/don’t walk is ped clearance walk is ped clearance intervalinterval

Very counterintuitiveVery counterintuitive

Problem with current system:Problem with current system:Pedestrians not sure if they can start during Pedestrians not sure if they can start during

flashing don’t walkflashing don’t walkBoston MA

Corvallis OR

Problem with current system:Problem with current system:Pedestrians not sure if they can start during Pedestrians not sure if they can start during

flashing don’t walkflashing don’t walk

Pedestrian count-down signal tells pedestrians Pedestrian count-down signal tells pedestrians how much crossing time is left …how much crossing time is left …

Springfield OR

Reno NV

Pedestrian count-down signal tells pedestrians Pedestrian count-down signal tells pedestrians how much crossing time is left …how much crossing time is left …

Results from San Francisco:Results from San Francisco:

25% Crash Reduction Factor after 25% Crash Reduction Factor after countdown signals installedcountdown signals installed

Countdown Clocks

• The existing option of using pedestrian countdown displays will now be a requirement for all new ped installations

• All existing pedestrian signal installations should be upgraded with countdown clocks within 10 years

• Only exception is where the duration of the pedestrian change interval (flashing Don’t Walk) is less than 7 seconds

Countdown Clocks in MUTCD

• Old MUTCD recommends using a pedestrian walking speed of 4.0 fps, and at crossings with older or disabled pedestrians, use 3.0 fps

Pedestrian signal timing

• However, recent studies found that 4.0 fps based on average walking speeds (not 15th percentile)

• New NCUTCD will use 3.5 fps for FDW and 3.0 fps for overall WALK phase

Crosswalks

Basic crosswalk question:

Do crosswalks increase safety, or do they Do crosswalks increase safety, or do they encourage pedestrians to cross without looking?encourage pedestrians to cross without looking?

(“(“false sense of securityfalse sense of security”)”)

Safety Effects of Marked vs Unmarked Crosswalks at Uncontrolled Locations: Executive

Summary and Recommended Guidelines

U.S. Department of TransportationFederal Highway AdministrationResearch and DevelopmentTurner-Fairbank Highway Research Center6300 Georgetown PikeMcLean, VA 22101-2296

byUNC Highway

Safety Research Center

March 2002

1. OK to mark crosswalks at ADT <10,000 w/o median

2. OK to mark crosswalks at ADT <15,000 w median

3. Medians reduce crash risk significantly

4. Marked crosswalk alone not recommended on high ADT roadways

5. Signalization or other treatments should be considered where large portion of pedestrians are young and/or elderly

Conclusions/recommendations

Many locations are suitable for a marked crosswalk

Suitable location for a marked crosswalk:Two-lane, ADT <10,000, high use, driver expectancy

Madison WI

Suitable location for a marked crosswalk:Two-lane, slow speed, high use, driver expectancy

Washington DC

Crosswalk MarkingsCrosswalk Markings

Once the decision has been made Once the decision has been made to mark a crosswalk,to mark a crosswalk,

the crosswalk must be visible to the crosswalk must be visible to thethe

DRIVERDRIVER

What the pedestrian sees

What the driver sees

Visible Crosswalks

Crosswalk Marking Types

Crosswalk Visibility

Longitudinal markings are more visible to Longitudinal markings are more visible to driver at a distancedriver at a distance

What the pedestrian sees

What the driver sees

Continental Markings

Visible Crosswalks

Textured xwalks: in theory, more visible. Textured xwalks: in theory, more visible. Reality?Reality?

What the pedestrian seesWhat the pedestrian sees

Corvallis OR

What the driver seesWhat the driver sees

Corvallis OR

Supplement textured crosswalks with white stripes to ensure visibility

Phoenix OR

Brick Street with Brick Street with asphalt asphalt crosswalkscrosswalks

Pedestrian Pedestrian perspectiveperspective

Orlando FL

DriverDriverperspectiveperspective

Orlando FL

Curb Extensions

– Relocate obstructions

– Eliminate parking on approaches

– Curb extensions when parking remains

AASHTO Ped GuideIntersection Design – Sight Lines

and Curb Bulbs

Curb extensions

Most focus has been on reducing crossing distance

Better visibility (both ways) Traffic calming Room for street furniture Additional on-street parking *

* corner is “protected”

Other advantages

Pedestrian is waiting on curb, behind parked car

Salem OR

Curb extension places pedestrian where he can see and be seen

A new way to look at curb extensions

Not something you add to a street

Imagine the street w/o on-street parking

Now think of parking as the bonus!

Curb extension integrated with the sidewalk

Consider this your Consider this your normal curb linenormal curb line

Not thisNot this

Fredericksburg VA

Transit

Transit Objectives

Ensure transit stops are convenient and accessible

Ensure transit users can safely cross the street at every transit stop

Address transit operators concerns Address other road users needs

Transit: designing for successful intermodalismTransit: designing for successful intermodalism

Transit: bus is most common modeTransit: bus is most common mode

Madison WI

Transit: only choice for many peopleTransit: only choice for many people

Madison WI

Sidewalks should be wide enough to provide Sidewalks should be wide enough to provide space for waiting, boarding and passing.space for waiting, boarding and passing.

Widen beyond ADA minimum for wheelchair padWiden beyond ADA minimum for wheelchair pad

Narrow curbside sidewalk provides insufficient Narrow curbside sidewalk provides insufficient space for waitingspace for waiting

Honolulu HI

Narrow curbside sidewalk provides insufficient Narrow curbside sidewalk provides insufficient space for waiting especially when bus comes & space for waiting especially when bus comes &

people boardpeople boardHonolulu HI

Bus shelter placement: it should not obstruct Bus shelter placement: it should not obstruct sidewalksidewalk

Portland OR

Bus shelters must be accessible Bus shelters must be accessible (grass around (grass around it is inaccessible)it is inaccessible)

Honolulu HI

Bus shelters must be accessible Bus shelters must be accessible (grass around (grass around it is inaccessible)it is inaccessible)

Separated sidewalk allows bus shelter placement in Separated sidewalk allows bus shelter placement in planter stripplanter strip

Eugene OR

All known crossing techniques apply to transit stopsAll known crossing techniques apply to transit stops

Portland OR

Place crosswalks behind bus stop!Place crosswalks behind bus stop!

Madison WI

Why?Why?1.1. Peds can see trafficPeds can see traffic2.2. Bus driver can moveBus driver can move3.3. Bus doesn’t run over pedsBus doesn’t run over peds

Bicycles

Definition: Bike Route System

• “Bikeway” is generic term to cover any facility designated for

bicycle traffic

• Shared Roadway

Facility Selection

– Recognizes that most bicycle travel now occurs on streets and highways without bikeway designation

Facility Selection

• Signed Shared Roadway

– Signing “should indicate particular advantages to using the route over an alternative”

No point in striping local streets with bike lanes

Bike lanes most appropriate on urban thoroughfares

They get you from one part of town to another efficiently

Intersections stop or signal controlled – the “right way”

No point in striping local streets with bike lanes

Facility Selection

• Bicycle Lanes– Can reduce travel lane

RELATIVE DANGER INDEXOf various types of facilities

Major Streets w/o bike lanesMajor Streets w/o bike lanes 1.281.28 Minor Streets w/o bike lanesMinor Streets w/o bike lanes 1.04 *1.04 * Streets with bike lanesStreets with bike lanes 0.50.5 Mixed-use pathsMixed-use paths 0.670.67 SidewalksSidewalks 5.325.32(* = shared roadway)(* = shared roadway)

1.00 = median1.00 = median

Source: William Moritz, U.W. - “Accident Rates for Various Bicycle Facilities” - based on 2374 riders, 4.4 million miles

25%34%

Riders on sidewalk against traffic

Riders on road with traffic

Riders on road against traffic

Riders on sidewalk with traffic

Riders at sites with sidewalks & no bike lanes

Total sw riders: 64%

Bike Lanes: Effect on Rider Characteristics

Riders on sidewalk against traffic

Riders on road with traffic

Riders on road against traffic

Riders on sw with traffic

Riders at sites with sidewalks & bike lanes

Total sw riders: 24%

QUESTIONS?

COMMENTS?

CONCERNS?

John N. LaPlante, P.E., P.T.O.E. T.Y. Lin International Prepared for the: Annual Meeting of the...

Documents