PedPal Lite: An ATSC-Independent Safe Intersection Crossing App

PedPal is a smartphone app designed to assist pedestrians with disabilities in safely crossing signalized intersections, developed originally as part of the Federal Highway Administration’s Accessible Transportation Technology Research Initiative (ATTRI) [1,2]. PedPal interacts directly with the surtrac adaptive traffic signal control (ATSC) system operating at the intersection using real-time traveler-to-infrastructure (T2I) communication and standard DSRC messaging to provide crossing support to its user. Upon arrival at the intersection, PedPal receives and presents information to its user about the intersection’s geometry, crossing options, and current traffic signal state. When the user indicates her crossing intent, the app then communicates this information to the intersection (eliminating the need to locate and push a pedestrian call button), along with how much time is required by the user to safely cross the intersection. In response to receiving this information, the traffic signal system will set the pedestrian crossing time in the desired direction to ensure that upon getting the crossing signal, the user will receive crossing time that has been requested. More advanced PedPal capabilities include the ability to monitor user crossing progress in real-time, to recognize when the user is traveling slower than expected, and to trigger the traffic control system to dynamically extend the crossing time in such circumstances. The PedPal app is integrated with the smartphone's native accessible features and provides visual, auditory and haptic interaction modalities. This project focuses on producing a cheaper and more broadly deployable version of PedPal. Whereas the ability exploit surtrac’s real-time ATSC capabilities enable advanced capabilities such as dynamic extension of the current phase duration that enhance safety, its deployment cost to municipalities presents a significant barrier to widespread deployment of the PedPal technology. Furthermore, a recent UTC funded project centered on technology support for the 'complete trip' has expanded the scope of PedPal's capabilities in several new safety-related directions, none of which depend on interaction with surtrac. To foster more widespread deployment of the PedPal technology, this project will develop and pilot test a stand-alone version of PedPal (referred to as ‘PedPal-Lite’) that will interact directly with the hardware controller at the intersection via an ATSC-independent PedPal intersection manager. This manager will take over responsibility from the Surtrac ATSC system both for broadcasting information about the intersection and the current traffic control state to the smartphone app and for interacting with the traffic controller in response to messages received from the app, exploiting the same underlying T2I connectivity. The manager will run on a low-end processor residing in the cabinet at the intersection and will take advantage of the V2I-hub software module developed under sponsorship of FHWA to generate DSRC formatted messages for broadcast to PedPal users. To maximize deployment potential, the research team will focus integrating the PedPal intersection manager with controllers that support standard NTCIP interaction protocols. The research team will demonstrate and pilot test the developed PedPal-Lite variant on a TBD intersection near the CMU campus that is running a conventional fixed signal timing plan on a hardware controller that supports the NTCIP standard.


  • English


  • Status: Active
  • Funding: $98000
  • Contract Numbers:


  • Sponsor Organizations:

    Carnegie Mellon University

    Safety21 National UTC for Promoting Safety
    Pittsburgh, PA  United States  15213

    Office of the Assistant Secretary for Research and Technology

    University Transportation Center Program
  • Managing Organizations:

    Carnegie Mellon University

    Safety21 National UTC for Promoting Safety
    Pittsburgh, PA  United States  15213
  • Project Managers:

    Stearns, Amy

  • Performing Organizations:

    Carnegie Mellon University

  • Principal Investigators:

    Smith, Stephen

  • Start Date: 20230701
  • Expected Completion Date: 20240630
  • Actual Completion Date: 0
  • USDOT Program: University Transportation Centers

Subject/Index Terms

Filing Info

  • Accession Number: 01900369
  • Record Type: Research project
  • Source Agency: Safety21
  • Contract Numbers: 69A3552344811
  • Files: UTC, RIP
  • Created Date: Nov 21 2023 6:56PM