Car-Following Properties of a Commercial Adaptive Cruise Control System: A Pilot Field Test

Abstract

Automated driving systems, which can take over certain dynamic driving tasks from the driver, are becoming increasingly available in commercial vehicles. One of these automated driving systems widely introduced in commercial vehicles is adaptive cruise control (ACC). This system is designed to maintain certain desired driving speeds and time headways as chosen by drivers and based on the settings available within the system. The properties and actual performance of these systems will affect the traffic flow and its stability. However, the specific properties and their workings are rarely publicly available. Therefore, the main aim of this paper is to test the actual performance of a commercial ACC system under different desired speed and distance gap settings, as well as driving modes in a car-following situation. For this purpose, a pilot field test was conducted in the Netherlands in which two identical commercial vehicles equipped with ACC systems were driven simultaneously. The first vehicle was used to create a pre-specified speed profile by adapting the ACC system settings manually, whereas the second vehicle followed the lead vehicle when the ACC system was engaged to test its actual performance. The main findings indicate that the different system settings affect the car-following indicators, and system response times were found to be comparable to human response times. The eco mode was found to affect some of the car-following indicators, and it does not deteriorate safety below the safety level of driving with short headway setting in drive mode.

Characterizing Behavioral Differences of Autonomous Vehicles and Human-Driven Vehicles at Signalized Intersections Based on Waymo Open Dataset

“…The maximum acceleration is about 2.02 m/s 2 , which is lower than the value assumed for AVs in Niels et al ( 19 ) (3.0 m/s 2 ), but higher than the upper acceleration for AV in Şentürk Berktaş and Tanyel ( 12 ) (1.4 m/s 2 ). The starting response time to green light of HDVs is 0.70 s, which is slightly shorter than Clement et al ( 17 ) and Abraham ( 20 ), which reported values between 0.8 and 0.9 s. Contrary to the much shorter response time expected in the literature ( 19 , 13 , 20 ), it is 1.01 s for AVs which is comparable to or slightly longer than HDVs ( 6 ). In addition, some HDVs have a response time that is shorter than 0 s, meaning that they anticipate the green light and tend to react before the light turns green.…”

“…There are also some studies that directly investigated driving behavior of the adaptive cruise control (ACC) system when interacting with HDVs. For instance, Raju et al ( 6 ) tested the real performance of a commercial ACC system under different desired speeds in a car-following situation, and found that the system response times were not instantaneous but were rather comparable to human response times. Li et al ( 5 ) characterized car-following behavior of ACC vehicles based on empirical experiments, and explained the behaviors underlying mechanisms, such as factors influencing the response time, oscillation growth, and overshoot.…”

“…In some recent studies, researchers utilized field experiment data or real-world road-testing data to investigate the driving behavior of AVs and HDVs in mixed traffic ( 4 ), such as the driving behavior properties ( 5 , 6 ) and human drivers’ behavioral adaptations ( 7 – 9 ). However, these studies mainly focus on car-following scenarios instead of signalized intersections which play vital roles in traffic safety and efficiency ( 10 ).…”

Comparative Analysis of Following Distances in Different Adaptive Cruise Control Systems at Steady Speeds

“…As mentioned earlier, the shortest gap setting (setting 1) for all vehicles' ACCs has been applied to investigate driving safety marginal levels through analyzing distance gaps between each of the two following vehicles. This is also the procedure conducted by [27,34] as they indicated that long-distance gap settings leads to frequent cut-in situations by other vehicles. The first exploration of the empirical works revealed that at low and medium speed ranges, all ACC systems show plausible following distances that maintain sufficient precollision braking distance in case the preceding vehicle applied brakes suddenly.…”

“…The results of the study revealed that all of the ACC systems in the seven vehicle models tested were string unstable. Raju et al [27] have conducted field tests using two commercial vehicles equipped with ACC, in which the following vehicle tracked the leading vehicle's pace when the ACC system was activated to assess its real-world functionality. The results suggest that different system speed and gap settings have an impact on the indicators for car-following, and the system's response times were observed to be on par with human response times.…”