Business Access and Associated Benefits Provided by Roundabouts MTJ Roundabout Engineering Mark Johnson, PE 608.238.5000 www.mtjengineering.com ITE Rapid City July 1 st 2014 ROUNDABOUT ANALYSIS, PLANNING, DESIGN, OUTREACH, EDUCATION
Introduction
Introduction
Introduction
Traffic Planning with Roundabouts Roundabout Operational Characteristics Allow for: o Capacity at Intersection = Less Roadway Widths o Roadway Geometric Flexibility due to slower speeds o Intersection Spacing Versatility o Different Access Control Opportunities
Traffic Planning with Roundabouts
Traffic Planning Examples with Roundabouts Example Project: Huffman Road Corridor, Anchorage, AK o No Roadway Widening (3 Lanes) = const. within Ex. OW o Access Control Opportunities = Good Business Circulation o Improved Traffic Flow and Safety
Traffic Planning with Roundabouts 7 Lane Cross Section Flared Entries, Lane drop at Exit 2 Lane Cross Section 7 Lane Cross Section
Case Studies
Roundabout Design Case Study Mt Horeb, WI
STH 78/92 Mount Horeb, Wisconsin 2,000 VPH, 2,800 design Flared Two - lane entry Two- Thru lanes WB * Flared Two - lane entry, RT only Varying circulating width 24-32 * * 120 140 * * * * Single-lane entry Two-lane Tapered Exit * Business Access *
Mount Horeb, Wisconsin STH 78/92 Pedestrian Comparison 60s Signal 18s Roundabout
Mount Horeb, Wisconsin STH 78/92 Trucks
Mount Horeb, Wisconsin
Traffic Planning with Roundabouts ~30k ADT ~25k ADT 4 Lane 2 Lane Mt Horeb, Wisconsin
Roadway Planning 9 Lane Structure
Roadway Planning 3-4 Lanes ROW Saved
Traffic Planning Experience with Roundabouts ROUNDABOUT ANALYSIS, PLANNING, DESIGN, OUTREACH, EDUCATION
Traffic Planning with Roundabouts Development
Traffic Planning with Roundabouts 600,000 square foot mixed retail development, Green Oak Village Place
Traffic Planning with Roundabouts ~150 185 85
Small Commercial Development Questions ~600 Grocery Store
Small Commercial Development
Small Commercial Development Questions ~600
Small Commercial Development Questions ~600
Questions
Business Access 125 ICD Short Flared Two-Lane Entry Single-Lane Entry Aux RT Lanes (two types)
Redevelopment Monona, WI
Redevelopment Full or LT Access Precluded by proximity to signal Proposed Super Center 225,000 sq ft. $30M Project Vacant Land Assessed = $6M
Redevelopment * Business Access
Redevelopment 135
Two-lane approach Trucks 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 California Boulevard Roundabouts City of Napa 1/28/14 38
Directional Signing-Way Finding
HISTORIC DOWNT OWN Directional Signing- Simplified Entry HISTORIC DOWNT OWN Downtown Napa To Downtown Downtown Napa 1/28/14 40
Omni-Means - Built to Deliver 1/28/14 41
Omni-Means - Built to Deliver 1/28/14 42
Ramp Intersection Design Optimization Lane Drop/Merge in close proximity Accepting lane not readily visible to turning traffic High speed lane drop (with green light) 2 Lanes of traffic & short decision distance from ramp entrance Poor sight lines to approaching traffic 1/28/14 43
Ramp Intersection Design Optimization Acceleration Lane to Accommodate Merge (35mph) Lower Exit Speeds from Roundabout (<25mph) with Lane Drop Completed Prior to Merge (30mph) Simplified Decision Making Single EB Thru Lane with designated right turn pocket and improved sight lines = easier decision making 1/28/14 Raised Median Designates Pocket = Driver Comfort 44
Traffic Planning with Roundabouts Summary o Roundabout Operational Characteristics Allow for: o Capacity Improvement with Reduced Roadway Widening o Intersection Spacing Versatility o Access Control Opportunities for Improved Business Access and circulation o Need further US research and publication to document these differences. o Need Research and Industry Documentation to Codify Roadway Planning Criteria for Roundabout Intersections
Thank You/Questions MTJ Roundabout Engineering Mark Johnson, PE 608.238.5000 www.mtjengineering.com