Exploring the impact of a coordinated variable speed limit control on congestion distribution in freeway

Abstract

Active traffic demand management Variable speed limit Extended METANET model Freeway queue Congestion distribution a b s t r a c tOver the past few decades, urban freeway congestion has been highly recognized as a serious and worsening traffic problem in the world. To relieve freeway congestion, several active traffic and demand management (ATDM) methods have been developed. Among them, variable speed limit (VSL) aims at regulating freeway mainline flow upstream to meet existing capacity and to harmonize vehicle speed. However, congestion may still be inevitable even with VSL implemented due to extremely high demand in actual practice.This study modified an existing VSL strategy by adding a new local constraint to suggest an achievable speed limit during the control period. As a queue is a product of the congestion phenomenon in freeway, the incentives of a queue build-up in the applied coordinated VSL control situation were analyzed. Considering a congestion occurrence (a queue build-up) characterized by a sudden and sharp speed drop, speed contours were utilized to demonstrate the congestion distribution over a whole freeway network in various scenarios. Finally, congestion distributions found in both VSL control and non-VS control situations for various scenarios were investigated to explore the impact of the applied coordinated VSL control on the congestion distribution. An authentic stretch of Whitemud Drive (WMD), an urban freeway corridor in Edmonton, Alberta, Canada, was employed to implement this modified coordinated VSL control strategy; and a calibrated micro-simulation VISSIM model (model functions) was applied as the substitute of the real-world traffic system to test the above mentioned performance. The exploration task in this study can lay the groundwork for future research on how to improve the presented VSL control strategy for achieving the congestion mitigation effect on freeway. .e lsev ie r. co m/ lo cate/ j tte j o u r n a l o f t r a f fi c a n d t r a n s p o r t a t i o n e n g i n e e r i n g ( e n g l i s h e d i t i o n ) 2 0 1 5 ; 2 ( 3 ) : 1 6 7 e1 7 8 http://dx.

Assessment of the Speed Management Impact on Road Traffic Safety on the Sections of Motorways and Expressways Using Simulation Methods

“…Previous research on VSL systems [ 111 , 112 ], or co-operative VSL systems (C-VSLSs) [ 113 , 114 , 115 ] used simulation traffic models but were mostly conducted to assess traffic conditions without considering road safety. Yu and Abdel-Aty [ 116 ] found a level of safety that increased with VSL techniques on steep mountain bottlenecks using VISSIM microscopic simulation software.…”

Modified Traffic Flow Model with Connected Vehicle Microscopic Data for Proactive Variable Speed Limit Control

“…Constraints. The constraints of the METANET model by Cao et al [33] are adopted in this paper. Let , and be the minimum speed, maximum speed, and maximum speed difference.…”

“…The objective function of VSL optimization was set as the weighted sum of total time spent (TTS) and total travel distance (TTD), in order to improve the mobility of the network, as suggested by Cao et al [33] and couple other previous studies. The speed limits associated with the minimum objective function are selected as the optimal speed limits.…”

Optimization of the Allowable Speed on Iran’s Freeways to Reduce Violations and Accidents, Using Zero-Truncated Poisson Regression Model

“…It should be noted that the reason for enforcing speed limit is not always the safety purposes. The traffic chaos can also be resolved by implementing different speed limits [9].…”