Agenda. Introduction to Roundabouts. Introduction to Roundabouts. Introduction to Roundabouts 6/6/2018

Transcription

1 PROPOSED PROJECT SAFETY AND OPERATIONAL IMPROVEMENTS TO THE INTERSECTION OF ROUTE 106 (NEW CANAAN ROAD) AND BELDEN HILL ROAD Connecticut Department of Transportation Representatives Division of Highway Design Marissa Washburn, P.E. Project Manager (860) Emin Basic, P.E. Project Engineer (860) Concept Used in Europe for many years, have become very popular in U.S. due to reductions in crashes and congestion Similarities to old traffic circles but with significant differences Drivers yield when entering Over 3,000 in U.S., including Colorado, Florida, Maryland, Vermont, many others (Including Connecticut) Similarities to old traffic circles and rotaries but with significant differences No weaving No lane changing Much smaller circle These factors reduce speeds, congestion, and crashes Different Types - Single lane vs. Multi-lane Single Lane Roundabout West Haven (Before) Similarities to old traffic circles but with significant differences 1

2 Dual Lane Roundabout Malta, NY Single Lane Roundabout West Haven (After) Physical Attributes Raised non-mountable center island with mountable truck apron Splitter islands Horizontal deflection on approaches Poor Deflection Very High Speeds Route 188 and Route 334 Seymour, CT Physical Attributes Slow Speeds Long Splitter Islands Raised non-mountable center island with mountable truck apron Splitter islands Horizontal deflection on approaches Operational Attributes Large Central Island with Truck Apron Route 188 and Route 334 Seymour, CT Curvature to Approach Lower Speeds (15-25 MPH) No left turns Less information to process Reduced conflict points 2

3 General Roundabout Information General Roundabout Information Reduction in conflict points Safety Benefits Based on a study from the Insurance Institute for Highway Safety (IIHS) ( *Crossing conflicts highest chance of injury (angle type, intersecting path, etc.) Total crashes reduced by 37% Injury crashes reduced by 75% Fatal/Incapacitating crashes reduced by 90% Pedestrian crashes reduced by 40% Proposed Project Location Project Location Neighboring Towns Primary Highways New York Wilton Weston Easton Secondary Highways Local Roads Westport New Canaan Norwalk History 2 Previous Requests sent to Traffic Division 2006 Traffic Division inquiry outcome Was not pursued further 2017 Traffic Division inquiry During course of review, Highway approached for input 2017 Highway Division study initiated due to unusual number of crashes Safety Congestion Average Traffic (2014) Higher than expected number of angle type crashes and injuries Peak hour congestion Serves as Route 7 bypass to downtown Norwalk 5,700 vpd on Route 106 9,400 vpd on Belden Hill Road 3

4 X X # of Crashes # of Injuries Crash Diagram Based on a 3 year Period (1/1/2015 to 12/31/2017) 21 Total Crashes/4 Injuries Belden Hill Road Southbound Approach Route 106 Westbound Approach Belden Hill Road Northbound Approach Roundabout General Information Route 106 Eastbound Approach *continued past curve 4

5 Proposed Conceptual Design Preliminary Concept Virtually eliminates angle type injury crashes Yield on all approaches allow clearly defined driver right of way Existing Condition (Counts taken 1/5/2017) VISSIM Simulation Video After Simulation (Counts taken 1/5/2017) 5

6 Summary Existing Proposed Concern R.O.W. Impacts Total Cost All-Way Stop Controlled Modern Roundabout Crash History and Congestion 3 Property Owners* Approximately $2.6 Million Questions/Comments Please feel free to contact us Marissa Washburn, P.E. Project Manager (860) Marissa.Washburn@ct.gov Thank You Emin Basic, P.E. Project Engineer (860) Emin.Basic@ct.gov *Additional property impacts may result due to necessity of grading easements 6