Transit Vehicle-to-Vehicle (V2V) Research

Overall Progress and Insights

Research Accomplishments

The USDOT has conducted the following research to incorporate transit into the Connected Vehicle Environment. The research includes:

• Transit Vehicle Collision Characteristics for Connected Vehicle Applications Research: Analysis of Collisions Involving Transit Vehicles and Applicability of Connected Vehicle Solutions: Due to its unique characteristics and behaviors, such as vehicle size and frequent stops/starts, transit often deals with safety challenges and priorities that are often different from those for light duty and commercial vehicles. The purpose of this study was to identify candidate transit crash scenarios for near-term Connected Vehicle safety research using data from the 2010 National Transit Database (NTD). The study identifies motor bus collision types according to collision characteristics, including the type of object the transit vehicle collided with (e.g., pedestrian, motor vehicles, infrastructure elements, etc.), the location of the collision (e.g., mid-block or at an intersection), and the geographic relationship between vehicles when they collided. The study revealed some prominent characteristics (such as geographic relationship between vehicles) related to motor bus crashes, and how these characteristics are amenable to connected vehicle solutions. The study then ranks collision types by frequency, cost, and average cost per crash. The report, FHWA-JPO-13-116, is available from the National Transportation Library.

• An Assessment of the Use of Light Vehicle Safety Applications for Transit: Using theNHTSA Safety Communications-Applications (VSC-A) Study, the study evaluates the applicability of current light vehicle safety applications for use on transit vehicles in revenue service operation, including identification of changes that would be required to those applications in order to apply them to transit vehicles. The report, FHWA-JPO-12-088, is available from the National Transportation Library.

• Feasibility Assessment of the Use of Transit Bus Driving Simulators: The study assess the feasibility of modifying current transit bus driving simulations for connected vehicle research purposes including driver-vehicle interface testing; driver acceptance and training; transit applications evaluation; human factors analysis; cost-effectiveness; and resource requirements. The report, FHWA-JPO-12-090, is available from the National Transportation Library..
• Transit Safety Retrofit Package (TRP): This project retrofitted three University of Michigan transit buses with Connected Vehicle technologies and safety applications. Specifically, the project developed, tested, installed, deployed, and maintained three basic safety applications – Emergency Electronic Brake Lights (EEBL), Forward Collision Warning (FCW), and Curve Speed Warning (CSW), and developed two new transit-specific safety applications – Pedestrian in Signalized Crosswalk Warning (PCW) and Vehicle Turning Right in Front of Bus Warning (VTRW); participated in the USDOT’s Safety Pilot Model Deployment; and collected and provided data from the TRP-equipped buses to the Volpe Center for an independent evaluation of results. Three of the five applications involved V2V communications, as identified above in the Research Plan. The project report, FHWA-JPO-14-142, is available from the National Transportation Library.

Critical Research Insights

• Based on the analysis of NTD collision statistics, recommendations for potential application areas for Connected Vehicle transit safety include:
  • Transit-Vehicle/Pedestrian Warning Applications: These applications may consider vehicle-to-infrastructure (V2I) or vehicle-to-pedestrian (V2P) communications to provide warnings to transit vehicles of a pedestrian’s presence in the roadway – either in a crosswalk or outside of the crosswalk.
  • Bus Stop Warning Applications: Using vehicle awareness messages, applications could be developed to alert nearby vehicles or pedestrians of the presence of a transit vehicle at or near a bus stop.
  • Left Turn Assist Warning Applications: These applications could provide information to drivers performing unprotected left turns to judge the gaps in oncoming traffic and to inform them of hazards to completing a safe left turn. These applications may be supported using vehicle-to-vehicle (V2V) communications where vehicles share information about their location, speed, trajectories, and other vehicles at the intersection.
  • Forward Collision Warning Applications: These applications could alert and then warn drivers if they fail to brake when a vehicle in their path is stopped or traveling slower.
  • Blind Spot Warning/Lane Change Warning Applications: These applications could warn drivers when they try to change lanes if there is a car in the blind spot of an overtaking vehicle.
  • Angle Collisions at Intersections Warning Applications: These applications could provide warnings to drivers at signalized intersections, at intersections equipped with stop signs, highway rail intersections (HRI), or light rail intersections.
• Results from the assessment of light vehicle safety applications for transit reveals that the applications can be leveraged for transit, but some constraints will need to be addressed. For instance, the results note that the BSM will need to include vehicle height and length as buses are moving in mixed traffic. Another important insight is that an articulated bus — made in two or more sections for easier turning — requires different application criteria than a conventional bus or light vehicle. In addition, buses accelerate and decelerate more slowly than other vehicles and require longer stopping distances. These modifications will be necessary to ensure that transit is a safe as well as an integrated part of the Connected Vehicle Environment.
• Developing and testing safety, mobility, and environmental applications for transit vehicles is expensive and time consuming. Once a system is designed, components must be developed and integrated. A field test site must be selected and a test system deployed, data gathered and analyzed, and findings documented. The use of transit bus driving simulators to test and evaluate proposed transit technologies would reduce the time and cost associated with executing a field operational test.

• Within the Model Deployment Connected Vehicle architecture, TRP employed V2V (and V2I) technologies based on Dedicated Short-Range Communications (DSRC), to ultimately determine if these technologies could be combined with the on-board transit safety applications to provide real-time alerting to the transit bus driver. Major conclusions and lessons learned from the TRP project include:
• Transit bus drivers expressed acceptance of the TRP concept.
• There was a high rate of false alerts for the VTRW application due to GPS limitations.
• DSRC radio technology performed well; there were no TRP problems traced to DSRC radio communications.
• Short-term system refinements yielded expected performance improvements.

Next Steps

• An analysis of data from the TRP project for an independent evaluation is underway. Information from evaluation should be available in early 2015.
• The Department is considering and prioritizing additional transit V2V safety applications for development and testing.