Improving Walkability Through Control Strategies at Signalized Intersections

Sirisha Kothuri, Portland State University

Co-investigators:

Summary:

The goal of signal timing at an intersection should be to separate conflicting movements in time, maximizing safety and efficiency for all users. In many jurisdictions, however, signal timing objectives have traditionally focused on allowing vehicle progression and reducing vehicular delay and stops. While these are important considerations in many contexts, other users (especially pedestrians) deserve similar focus and control strategies. Recent updates to the Highway Capacity Manual (HCM 2010) have included specific multimodal delay modeling techniques offering a bit more accommodation to pedestrians, but still remain heavily vehicle-centric.  While strategies such as an exclusive pedestrian phase and leading pedestrian intervals can help improve the safety of pedestrian operations, legacy service of pedestrians requires that they still must wait for ‘their turn’—which at times means they experience delays much in excess of those that would be deemed acceptable for a motor vehicle at the same location. Excessive delay can lead to pedestrian frustration, non-compliance and ultimately decreased safety. In the North American context, there is limited research on incorporating alternative pedestrian treatments at signalized intersections.

This project builds on recent research completed at Portland State University exploring a concept of pedestrian priority which may be warranted when pedestrian demand is low and vehicular demand is moderate. This proposed research seeks to answer several questions regarding the influence of numerous alternative pedestrian treatments, including leading pedestrian intervals, shorter cycle lengths, the elimination of vehicle coordination during specific periods, as well as pedestrian priority service. First, what is the impact of these treatments on the delays of all users at an intersection?  Second, what operational and geometric characteristics of a specific location might make one or more of these treatments advantageous to deploy?  Third, what impacts might these treatments, deployed individually or in combination, have on pedestrian compliance and safety? 

To answer these questions, we propose two-pronged approach. First, we will develop and test a software-in-the-loop (SITL) simulation will be used to examine the operational impacts of the various treatments.  Second and uniquely, the research team will also develop an algorithm for the implementation of pedestrian priority will be developed and then deployed using the test bed of SE Division Street/122nd Avenue in East Portland, as well as at least one other location in the state of Arizona using both the 2070 and NEMA controller standards.  Deployment data will be collected and then compared with simulated data to identify additional impacts.  

Our proposed research is novel in that its overall goal goes beyond simply accommodating pedestrians at signalized intersections to actually encouraging walking by providing field implmentable solutions for reducing pedestrian delays. These findings may have a nationwide appeal, particularly for cities that are looking to create safe, sustainable streets capable of accommodating multi-modes, which are an integral component in the development of livable communities.

Project Details

Project Type:
Research
Project Status:
Completed
End Date:
July 31,2016
UTC Grant Cycle:
Tier 1 Round 3
UTC Funding:
$109,075

Other Products

  • TRB (PRESENTATION)
  • International Conference on Engineering and Applied Sciences (PRESENTATION)
  • ITEMeeting (PRESENTATION)
  • 10.3141/2558-03. (PUBLICATION)