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district wide roundabout

District-Wide Roundabout Program

Urban Engineers is assisting PennDOT District 6-0 with the development of a regional roundabout program. We identify intersections where a roundabout would be a suitable safety countermeasure and advance those intersections to engineering design.

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District-wide Roundabout Program

PennDOT District 6-0

Urban is assisting PennDOT District 6-0 with the development of a regional roundabout program to address safety needs at intersections within the District. The program began with a data-driven process to locate candidate sites, followed by close examination and screening to identify suitable candidates. The goal of this project is to address safety needs by identifying intersections where a roundabout would be a suitable safety countermeasure, and to advance those intersections to engineering design.

 

Urban developed a dataset of more than 18,000 intersections on State Routes in the five-county region. Candidate intersections were evaluated using crashes within 250’ of the intersection over a five-year period. To perform the crash summaries, ArcGIS’s linear referencing tools were used to create and select the correct route segments per intersection. Intersections with a history of angle and head-on crashes were closely examined as these types of crashes are likely to be reduced with the implementation of a roundabout. 

 

full pyramid

The primary screening used GIS to analyze crash history, and was followed by a secondary screening to determine suitability for a roundabout.

crashes

The analysis examined more than 18,000 intersections in five Pennsylvania counties. More than 170,000 crashes were analyzed during the five-year period.

func class roundabout

Developing the intersection set required a methodical examination of intersecting points to select appropriate intersections.

selected roundabout

The analysis focused only on the crashes that occurred on routes touching the intersection.

chester gisimage

Intersections with high rates of angle and head-on crashes were examined to identify good candidates for a roundabout.

roundabout bucks county map

A web-based format was developed to present the results and foster communications.

easton rd new britain rd

Concept for a pair of roundabouts for a bifurcated roadway.

castor ave wyoming ave

Concept to retrofit an existing roundabout that lacked deflection on the approach roadways.

 

Since the goal of this project is to find suitable projects for the Highway Safety Improvement Program (HSIP), crash history was the primary screening criteria. Urban used additional criteria to evaluate the suitability of the site for a roundabout. Intersections were evaluated based on volume characteristics, municipal support, roadway characteristics and geometry, environment, land use, roadway network impacts, and planned projects.

 

Following the GIS analysis, Urban discussed candidate intersections with PennDOT and County Planning partners to determine feasibility and local support for a roundabout project. Roundabout concepts were developed for select intersections along with preliminary cost estimates. Urban evaluated the concepts using the Highway Safety Manual (HSM), which provides the tools needed to conduct quantitative safety analyses, and improves decision making based on safety performance. The selected intersections will be prioritized by PennDOT District 6-0 and submitted for competitive HSIP funding.

 

Highlights

  • Completed a data-driven screening process to identify candidate intersections in need of safety improvements
  • Developed an intersection dataset of more than 18,000 intersections in the five-county region
  • Completed a crash analysis for intersection related crashes using ArcGIS
  • Evaluated candidate intersections to recommend sites that were suitable for a roundabout conversion
  • Developed concepts and cost estimates for selected intersections
  • Conducted quantitative safety analyses using the tools in the HSM to evaluate the concepts
  • Submitted concepts for competitive HSIP funding