This study conducted three test scenarios in a traffic jam assist (TJA) system to assess how well test protocols can be performed and how useful performance criteria is. The first scenario had the lead vehicle decelerate, accelerate, then decelerate (LVDAD); this evaluated the TJA system’s ability to respond to a principal other vehicle (POV). The second was the Suddenly Revealed Stopped Vehicle (SRSV) scenario, which evaluated the system’s ability to respond to a stationary POV with secondary other vehicles (SOVs) surrounding it. The last was the Lead Vehicle Lane Change with Braking (LVLCB) scenario, which evaluated the system’s ability to respond to a moving POV that braked either during or after a lane change. All tests were conducted on the Skid Pad of the Transportation Research Center in East Liberty, Ohio. Sensor data was collected with an in-vehicle data system utilizing real-time kinematic corrections while video data was recorded with cameras. Researchers also assessed revisions to the National Highway Traffic Safety Administration’s (NHTSA) April 2018 draft TJA test procedure.
The study summarizes the following recommendations for further refinement for the NHTSA April 2018 TJA draft research test procedure:
- Reduce the 0.6g deceleration to 0.5g to improve test execution, increase tire and braking component longevity, and achieve higher POV deceleration magnitudes for LVLCB tests.
- Change the lane change threshold value from 0.02g to 0.03g to accurately define the POV lane change completion of LVLCB tests.
- Change the time when the POV must begin braking after initiating and completing its lane change from 100 ms to 250 ms to better satisfy LVLCB-scenario-related performance criteria.
- Use the farthest subject vehicle (SV) adaptive cruise control (ACC) headway setting (or the setting allowing the vehicle to travel the longest distance if another vehicle is ahead of it) and remove the 10 and 20-mi/h tests to reduce test burden.
- Specify the same ACC setting for all scenarios and test conditions to minimize the possibility of utilizing an incorrect setting.