Post on 07-Aug-2020
transcript
ROUNDABOUT ANALYSIS, PLANNING, DESIGN, OUTREACH, EDUCATION
ITE Rapid City July 1st 2014 MTJ Roundabout Engineering Mark Johnson, PE608.238.5000www.mtjengineering.com
Business Access and Associated Benefits Provided by Roundabouts
Introduction
Introduction
Introduction
Roundabout Operational Characteristics Allow for:o Capacity at Intersection = Less Roadway Widthso Roadway Geometric Flexibility due to slower speedso Intersection Spacing Versatility o Different Access Control Opportunities
Traffic Planning with Roundabouts
Traffic Planning with Roundabouts
Traffic Planning Examples with RoundaboutsExample Project: Huffman Road Corridor,
Anchorage, AKo No Roadway Widening (3 Lanes) = const. within Ex. OW o Access Control Opportunities = Good Business Circulationo Improved Traffic Flow and Safety
Traffic Planning with Roundabouts
Flared Entries, Lane drop at Exit
7 Lane Cross Section
7 Lane Cross Section
2 Lane Cross Section
Case Studies
Case Study Mt Horeb, WI
Roundabout Design
STH 78/92 Mount Horeb, Wisconsin
2,000 VPH, 2,800 design Flared Two -lane entry
Two-lane Tapered Exit
Flared Two -lane entry, RT only
Two- Thru lanes WB
Single-lane entryVarying
circulating width 24-32’ *
* Business Access
*
*
**
**
*
120’140’
Mount Horeb, Wisconsin STH 78/92
Pedestrian Comparison
60s Signal 18s Roundabout
Mount Horeb, Wisconsin STH 78/92
Trucks
Mount Horeb, Wisconsin
Mt Horeb, Wisconsin
~30k ADT
4 Lane~25k ADT
2 Lane
Traffic Planning with Roundabouts
Roadway Planning9 Lane Structure
Roadway Planning
3-4 LanesROW Saved
ROUNDABOUT ANALYSIS, PLANNING, DESIGN, OUTREACH, EDUCATION
•ExperienceTraffic Planning with Roundabouts
Development
Traffic Planning with Roundabouts
600,000 square foot mixed retail development, ‘Green Oak Village Place
Traffic Planning with Roundabouts
~150’
85’185’
Traffic Planning with Roundabouts
Questions
Small Commercial Development
~600’
Grocery Store
Small Commercial Development
Questions
Small Commercial Development
~600’
Questions
Small Commercial Development
~600’
Questions
Business Access
• 125’ ICD• Short Flared Two-Lane Entry• Single-Lane Entry • Aux RT Lanes (two types)
Redevelopment
Monona, WI
Redevelopment
Proposed Super Center 225,000 sq ft.$30M Project
Vacant Land Assessed = $6M
Full or LT Access Precluded by proximity to signal
Redevelopment
* Business Access
Redevelopment
135’
TrucksTwo-lane approach
One-lane approach Source: MTJ
Redevelopment
Trucks Video Taken From Here
Source: MTJ
Effective Lane Utilization with Flared Entry Design
Project Area
1/28/14 37
Proposed Project
1/28/14 38
California Boulevard Roundabouts– City of Napa
Directional Signing-Way Finding
Directional Signing- Simplified Entry
1/28/14 40
To Downtown
HISTORIC DOWNT OWN
DowntownNapa
HISTORIC DOWNT OWN
DowntownNapa
411/28/14
Omni-Means - Built to Deliver
421/28/14
Omni-Means - Built to Deliver
431/28/14
Ramp Intersection Design Optimization
Accepting lane not readily visible to turning trafficLane Drop/Merge
in close proximity
2 Lanes of traffic & short decision distance from ramp entrance
Poor sight lines to approaching traffic
High speed lane drop (with green light)
441/28/14
Ramp Intersection Design Optimization
Lower Exit Speeds from Roundabout (<25mph) with Lane Drop Completed Prior to Merge (30mph)
Single EB Thru Lane with designated right turn pocket and improved sight lines = easier decision making
Acceleration Lane to Accommodate Merge (35mph)
Raised Median Designates Pocket =Driver Comfort
Simplified Decision Making
o Roundabout Operational Characteristics Allow for:o Capacity Improvement with Reduced Roadway Wideningo Intersection Spacing Versatilityo Access Control Opportunities for Improved Business Access and
circulationo Need further US research and publication to document these
differences.
o Need Research and Industry Documentation to Codify Roadway Planning Criteria for Roundabout Intersections
Traffic Planning with Roundabouts Summary
Thank You/Questions
MTJ Roundabout EngineeringMark Johnson, PE608.238.5000www.mtjengineering.com