PedX: Automation for Safer Pedestrian Street Lighting at Intersections

Streetlights have performed well for drivers and vehicle visibility, and LED streetlight luminaires, with their brighter illumination, have increased that visibility. Unfortunately, streetlighting for pedestrians has not been a high priority and LED streetlights exacerbate the problem with their directional light throw and higher contrast characteristics. It is possible to stand behind an LED streetlight pole, for example, and not be seen. LED streetlights’ directional lighting compromises a driver’s ability to detect vertical objects because the light is narrowly focused down with little horizontal light scattering often places pedestrians in silhouette. Increasing intersection illumination for greater driver visibility reduces pedestrian visibility. This project is focused on creating---and ultimately automating---better pedestrian lighting at roadway intersections where pedestrian visibility is critical. Three items are proposed: (1) Control of LED luminaires’ individual array diodes to improve crosswalk visibility, (2) luminary positioning for optimal driver visibility of pedestrians in crosswalks and at intersection sidewalks, and (3) synchronization of the proposed PedX system with Safety21’s PedPal app at intersection streetlights. PedPal’s PI, Stephen Smith, will serve as an advisor to ensure proper system integration. (1) Diode Control: LED streetlight arrays illuminate each diode equally when the luminaire is activated and perform equally when dimmed. The lumen intensity is equal at the light source and object illumination decreases depending on distance from the luminaire. Streetlights located at intersection corners are brighter across the intersection and fade outward toward oncoming drivers. Given diodes’ directional properties, pedestrians are either lit from top down or backlit the closer they are to the luminaire. By independently controlling the number of lumens produced by each diode, the source light can be selectively increased to highlight pedestrians in the crosswalks and automatically maintained year-round throughout the dusk-dawn cycle. (2) Streetlight Positioning: Streetlights are often atop the same pole that holds the traffic signal(s) with the luminaire positioned on the intersection’s diagonal axis or orthogonally in line with the signal arm. Pedestrians are either lit from the center of the intersection or in line with the pedestrian’s front/backside, not from the side as viewed by drivers. While they provide high visibility for drivers making turns, they cast pedestrians in shadows or silhouettes to oncoming drivers. In combination with diode control, positioning the luminaire is critical to good pedestrian illumination. (3) Smartphone Application: PedPal is an app for pedestrians requiring assistance crossing intersections. PedPal provides pedestrians with intersection information, including crossing options and signalization sequencing, notifies the signal controller of intent to cross and the person’s walking speed/traversal time, sets the signalization time for safe passage, and notifies the pedestrian when to cross. Working with the PedPal research team, the study will coordinate crosswalk lighting with the app and signalization. The research team expects this work to span two years, with the initial year (this project) dedicated to establishing the feasibility of the three outlined objectives. The subsequent year will concentrate on the development of a prototype for deployment and extensive field testing.

Language

  • English

Project

  • Status: Active
  • Funding: $200000
  • Contract Numbers:

    69A3552344811

  • Sponsor Organizations:

    Office of the Assistant Secretary for Research and Technology

    University Transportation Centers Program
    Department of Transportation
    Washington, DC  United States  20590
  • Managing Organizations:

    Carnegie Mellon University

    Pittsburgh, PA  United States 

    Safety21 University Transportation Center

    Carnegie Mellon University
    Pittsburgh, PA  United States  15213
  • Project Managers:

    Stearns, Amy

  • Performing Organizations:

    Carnegie Mellon University

    Pittsburgh, PA  United States 
  • Principal Investigators:

    Flanigan, Katherine

  • Start Date: 20240701
  • Expected Completion Date: 20250630
  • Actual Completion Date: 0
  • USDOT Program: University Transportation Centers

Subject/Index Terms

Filing Info

  • Accession Number: 01933397
  • Record Type: Research project
  • Source Agency: Safety21 University Transportation Center
  • Contract Numbers: 69A3552344811
  • Files: UTC, RIP
  • Created Date: Oct 13 2024 8:23AM