Investigating the impact of dynamic merge control strategies on driving behavior on rural and urban expressways – A driving simulator study

Abstract

Harsh decelerations and abrupt lane changes of drivers on the outer expressway lane in response to merging platoon vehicles from on-ramps increase the crash- and congestion risk on expressways. Several merge control approaches are worldwide implemented. However, there is a gap in knowledge which driving behaviors determine whether a particular merge control approach is best for a rural or urban expressway. This study tests a number of dynamic merge control strategies, such as lane control signalization (eventually combined with variable speed limits (VSL), on a 4-lane urban and rural expressway to measure the behavioral responses of drivers being directly exposed to platoon merging from on-ramps. Subsequently, a comparison was made with the driving behaviors in response to static merge control (e.g. merge warning signs or road marking treatment). The driving behavior of 66 drivers from the State of Qatar was recorded in a driving simulator and analyzed by means of a within-subject repeated measures analysis with univariate statistics. The results suggest that dynamic merge control is more effective for rural expressways considering the higher traffic speeds. The earlier lane changes contributed to smooth maneuvers and gradual speed reductions on the rural expressway and improved safe driving behavior as compared to static merge control. In contrast, the dynamic merge control did not deliver additional safety benefits on urban expressways and can be substituted by a low-cost static merge control approach. Policymakers aiming to improve traffic safety at expressway merging sections are advised to take the speed characteristics of the local expressway into account before implementing dynamic merge control.