Iowa Signal Phasing and Timing (SPaT) and MAP Demonstration Project: Phase I

Project Details







Iowa Department of Transportation

Principal Investigator
Anuj Sharma

Co-Director, REACTOR

Co-Principal Investigator
Christopher Day

Research Scientist, CTRE

Co-Principal Investigator
Neal Hawkins

Associate Director, InTrans

Co-Principal Investigator
Skylar Knickerbocker

Research Scientist, CTRE

About the research

This project is part of the main Iowa Department of Transportation-sponsored project, “Iowa DOT Operations Division Cooperative Autonomous Transportation (CAT) Research Support.”

Connected vehicles have the potential to change transportation in the near future. According to some estimates, use of vehicle-to-infrastructure (V2I) information to prioritize signal timing will reduce the overall delay (up to 27%) and can potentially cut down the CO2 emissions by 11%. Intersection-focused safety applications are expected to prevent an estimated 575,000 crashes and 5,100 fatalities per year. The benefits of connectivity will be further enhanced when compounded with autonomy. Self-driving vehicles are designed to utilize information beyond the extent of their physical sensors and thus optimally perform given the global conditions.

The applications of connected vehicles (CV) or connected autonomous vehicles (CAV) varies from reducing environmental impacts, through speed harmonization or speed management at intersection approaches, to improving safety by providing intersection movement assistance to drivers as well as pedestrians. Given that development of vehicle-to-vehicle communications is being spearheaded by automobile companies, American Association of State Highway and Transportation Officials (AASHTO) has set a challenge for state and local agencies to have 20 intersections (within each of the 50 states) equipped with the capability to communicate with connected vehicles by January 2020.

SPaT (Signal Phase and Timing) data provides information on signal states by movement, such as the current output state, min/max time remaining in the state, among other pieces of information essential for driver/vehicle decision-making. Map messages provide geometric intersection descriptions about lanes, stop bars, etc. Vehicles can also request priority, or preemption, using the communication link and position corrections that can be sent to the vehicle for centimeter-level accuracy.

The overall goal of this project is to enable a successful Iowa DOT implementation of SPaT message communication capabilities at 20 signalized intersections by the year 2020.

In the second phase (2018–19), an additional 15 intersections will be equipped with SPaT communication capabilities. The final phase (2019–20) will involve a comprehensive analysis of current corridors to identify a state-wide policy for selecting technologies and corridors for future connected capabilities.