Simulation Analysis of Truck-Restricted and High-Occupancy Vehicle Lanes

Abstract

Numerous studies have reported the efficacy of high-occupancy vehicle (HOV) lane restriction and truck lane restriction implemented independently, but the simultaneous use of both restrictions on an urban freeway corridor raises numerous operational and safety issues. This research study analyzed the operational and safety experience of an 83-mi corridor of I-95 in South Florida that has both HOV and truck lane restriction. Results of a field-validated VisSim simulation model showed that high-occupancy vehicles and automobiles gained significantly more travel time savings and speeds on the restricted lanes than on the general lanes. Also, vehicle queue lengths around critical merging and diverging areas increased significantly as the percentage of trucks increased. Results indicated that during peak traffic conditions right lanes had higher lane occupancy than left lanes, whereas during off-peak traffic conditions center lanes carried more vehicles per lane than the outermost lanes; these results suggest that congestion on right lanes forces automobiles to use left lanes. Furthermore, results showed that most lane changes occurred during peak traffic flow conditions—about twice that of off peak—and appreciable speed differences existed between restricted and nonrestricted lanes. Simulation results for off-peak traffic conditions did not show any noticeable changes in traffic operating characteristics resulting from lane restriction strategies. On the basis of these results, it can be fairly concluded that on urban freeways significant operational and safety benefits of the combined implementation of HOV and truck lane restrictions accrue during congested traffic conditions rather than during uncongested conditions.

Analysis of Reduction in Effective Capacities of High-Occupancy Vehicle Lanes Related to Traffic Behavior

“…A comparison between the data at these transition locations and the nonweaving sections did not reveal any significant difference. Simulation analysis studies have reported increased vehicle queue lengths around ingress and egress sections (13), and other studies have sought to develop methodologies for determining capacity reduction in HOV lanes near ingress and egress (weaving) sections (14). However, the data available in the current study do not have the granularity to allow for an exact determination of the capacity drops at the weaving sections.…”

Review, Experimental Evaluation and Policy Considerations of a Directional Time of Day Truck Restriction on Highways

“…These results imply that in order to significantly improve traffic congestion it might be more reasonable to implement a directional time of day truck restriction strategy as proposed in the current study. Siuhi and Mussa (2007) found that during peak hours, HOV lanes and car lanes experienced better travel times than did the lanes that permitted truck traffic. The leftmost lanes (including HOV lanes, which were restricted from trucks) had higher speeds than unrestricted lanes.…”

Dedicated Lanes, Tolls and ITS Technology

“…Garber and Liu, 2007) accident rates per vehicle-mile increase with volume, but costs fall because of reduced accident severity. Lane changes per vehicle-mile -which are correlated with accident rates -increase with the fraction of trucks in the traffic volume up to about 25%, but drop beyond that (Siuhi and Mussa, 2007). Studies differ as to whether variance in speeds contributes to crash rates.…”

“…Using simulation software Rakha et al (2005) concluded that providing separate lanes for trucks enhances performance as measured by speeds, fuel consumption and emissions. Not surprisingly, passenger vehicles benefit more from vehicle separation during peak hours when congestion is high (Siuhi and Mussa, 2007;Florida DOT, 2008) and on highway sections with extended upgrades. Lane restrictions are found to be more effective on highways with three or more lanes in each direction than on highways with only two (Stanley, 2009) and on freeways with limited access.…”