01628183

Component

Variable speed limit (VSL) systems, which can dynamically adjust the displayed speed limits based on the prevailing traffic stream and weather conditions, have emerged as a key traffic control measure on motorways around the world. Many researchers have examined the impacts of VSL control on driving behavior and have concluded that VSL systems can introduce some safety benefits. However, most of these existing studies were mainly using qualitative methods with insufficient efforts devoted to quantitative analysis. To quantify the impacts of different speed limits on the aggregated driving behavior, this study perform s statistical analysis on empirical traffic data collected from a European motorway under VSL control. The results show that different VSL values can effectively decrease the mean speed, the speed difference, and the percentage of small space headways when compared to No VSL control conditions. These observations are consistent with qualitative analysis results of previous studies. However, this study also shows that the changes in driving behavior variables follow a trend of first decreasing then increasing with the continuous decreasing in VSL values. This new observation implies that continue decreasing the VSL values after a certain threshold cannot lead to better safety benefits, while the greatest traffic safety benefits can probably be achieved by adopting the suitable VSL values that match with the prevailing traffic conditions.

This paper was sponsored by TRB committee AHB50 Standing Committee on Traffic Control Devices.

01618707

17-06348

English

13p

2017

Transportation Research Board 96th Annual Meeting

Digital/other

Figures; References (15) ; Tables

Behavior; Drivers; Traffic congestion; Traffic control; Variable speed limits

Highways; Operations and Traffic Management; Safety and Human Factors

Transportation Research Board Annual Meeting 2017 Paper #17-06348

TRIS, TRB, ATRI

Dec 8 2016 12:35PM