Evaluation of Driver Compliance to Displayed Variable Advisory Speed Limit Systems: Comparison between Germany and the U.S.

Abstract

Variable Speed Limit (VSL) and Variable Advisory Speed (VAS) systems are applications of a growing field of active traffic management systems (ATM). This technology aims to improve safety while reducing congestion and emissions. VSL is common on German freeways, harmonizing traffic flow during congestion and weather events. Portland, Oregon installed a VAS system (advisory meaning it is not automatically enforced) on an eleven km (7 mile) segment of heavily congested urban freeway. The Portland region maintains archived, high-resolution data of both VAS sign messages and speed detection loop feedback, permitting reconstruction of traffic and sign data. This work analyses over 30 days of archived data from the Portland site in order to study driver compliance to the VAS signs. The focus is to suggest methods and parameters to score system performance. Such an analysis could benefit new rollouts of VAS corridors by providing system performance feedback and shed light on options for improving system performance.

Keywords

Variable Advisory Speed ; Variable Speed Limits ; Compliance ; Traffic Management ; Evaluation

References

1. Ackaah et al., 2015 Ackaah, W., Huber, G., & Bogenberger, K. (2015). Quality Evaluation Method for Variable Speed Limit Systems. 94th Annual Transportation Research Board. Washington, D.C.: Transportation Research Board.
2. Associates, 2013 DKS Associates. (2013). Oregon Statewide Variable Speed System Concept of Operations. Portland, Oregon: Oregon Department of Transportation.
3. Downey, 2015 Downey, M. (2015). M.S. Thesis: Evaluating the Effects of a Congestion and Weather Responsive Advisory Variable Speed Limit System in Portland Oregon. Portland, Oregon: Portland State University.
4. Downey and Bertini, 2015 Downey, M., & Bertini, R.L. (2015). Evaluation of a Traffic and Weather Responsive Variable Advisory Speed System in Portland, Oregon. 94th Annual Transportation Research Board Meeting. Washington, D.C.: Transportation Research Board.
5. Weikl et al., 2013 Weikl, S., Bogenberger, K., & Bertini, R.L. (2013). Empirical Assessment of Traffic Management Effects of a Variable Speed Limit System on a German Autobahn: Before and After. Presented at the 92nd Annual Transportation Research Board Meeting. Washington, D.C.: Transportation Research Board.
6. Yanfei, 2013 Yanfei, S. (July 2013). Analysis of Speed Compliance in Rural Variable Speed Limit System. ITE Western District Annual Meeting. Phoenix.