Another View of Truck Lane Restrictions

2007

This paper examines the impacts of truck lane restriction on urban freeways using traffic simulation models. The study includes three main parts: Part (1) provides insights into conditions under which truck lane restrictions would work well; Part (2) identifies the best number of lanes to restrict and shows that this is an important factor in the success of lane restriction; Part (3) investigates potential impacts of truck lane restriction through a case study using a region with some of the highest truck volumes in the US, the I-710 ...

Trucks play a significant role in highway safety and operation because of their different operating characteristics. To mitigate the impact of truck traffic on operation and safety, some states, including Louisiana, have resorted to policies that restrict trucks in terms of lane use and speed limit on specific freeway segments. In this study, an investigation was conducted to measure the effectiveness of the implemented policies on an 18-mile four-lane elevated segment of I-10, where trucks are restricted to the right lane with a speed limit of 55 mph. One of the primary objectives of the research study was to examine the traffic characteristics and truck compliance to the restrictions over the study section. Traffic data was collected and analyzed for four different sites along the freeway corridor using the statistical methods presented in this paper. The basic statistical analysis showed that the speed in the left lane was much higher than it was in the right lane as a result of the imposed differential speed limit. The results also showed more trucks in the right lane than in the left lane, with a compliance rate in the range of 60% to 80% most of the time. To further evaluate more detailed aspects of the compliance of trucks to the differential speed limit policy, linear regression models were applied to determine the variables with the most significant effect on speed.

Transportation Research Record: Journal of the Transportation Research Board, 2019

Unnecessary traffic delays and vehicle emissions have adverse effects on quality of life. To solve the traffic congestion problem in the U.S.A., mitigation or elimination of bottlenecks is a top priority. Agencies across the U.S.A. have deployed several congestion mitigation strategies, such as lane and shoulder width reduction, which aim to adding lanes without significantly altering the footprint of the freeway. A limited number of studies have evaluated the operational benefits of lane narrowing. Although the Highway Capacity Manual does account for lane and shoulder widths, the adjustments that it provides are outdated. The goal of this research was to develop analytical models, compatible with the Highway Capacity Manual methods, to account for lane and shoulder width narrowing, using field data from across the U.S.A. This paper presents a new free-flow speed regression model, which accounts for lane and shoulder widths, and capacity adjustment factors depending on the lane width.

To improve traffic operation and safety, several states have implemented truck lane restriction and differential speed limit policies on freeways. The State of Louisiana introduced such restrictions on an 18-mile elevated four-lane rural segment of Interstate 10 (I-10) in response to an 11-vehicle crash in September 2003. The new control policies, implemented in 2005, have restricted trucks to the right lane only and reduce their speed limit to 55 mph. At the same time the speed limit for passenger cars was also reduced from 70 mph to 60 mph. This paper highlights the findings of a survey to assess truck drivers' perceptions and opinions of these restrictive policies. Another objective of the survey was to solicit ideas and input for other potential strategies that could be useful to the drivers. Overall, the results showed that the truckers were not in favor of the restrictions and they did not perceive that a significant safety benefits were being gained from restrictions. In fact, it was apparent that they felt it was safer to have uniform and higher speed limits and freedom to select a travel lane.

Lane management is a promising approach for congestion management through demand regulation, separation of traffic streams to reduce turbulence, and better utilization of available capacity. In response to the continually growing problem of urban congestion in the Birmingham, Alabama metropolitan area, this study examined the potential introduction of High Occupancy Vehicle Lanes (HOV) as a managed lanes strategy for improving traffic operations and assisting in congestion mitigation. More specifically, the study first reviewed lane management options and lessons learned from earlier HOV deployments efforts. Then microsimulation modeling was employed to quantify the potential operational impacts of implementation of HOV along a segment of I-65 freeway. Different design scenarios were considered and compared on the basis of measures of effectiveness including travel time, delay, travel speed, and emissions. Moreover, a detailed cost-benefit analysis was performed to estimate economic impacts from possible deployment and determine the most economically efficient investment alternative in the short-and long term.

… Record: Journal of …, 2005

The study evaluates a number of lane management strategies along one of the most highly traveled roadway sections of I-81 in the State of Virginia using the INTEGRATION traffic simulation software. The lane management strategies that are considered include the separation of heavy-duty trucks from light-duty traffic, the restriction of trucks to specific lanes, and the construction of climbing lanes at strategic locations. Overall, the results demonstrate that a physical separation of heavy-duty trucks from the regular traffic offers the maximum benefits in terms of efficiency, energy, and environmental benefits. The study also demonstrates that restricting trucks from the use of the leftmost lane offers the second highest benefits in terms of efficiency, energy, and environmental impacts.

Transportation Research Record: Journal of the Transportation Research Board, 2008

Previous research efforts have quantified the capacity of non-barrier-separated, high-occupancy vehicle (HOV) lanes. However, the majority of these efforts have focused on HOV lanes that usually operate well below capacity. In contrast, the I-85 HOV lanes in Atlanta, Georgia, usually operate under constrained flow conditions during morning and afternoon peak periods. This provides an opportunity to assess the relative performance of the HOV lane to the adjacent general-purpose (GP) lanes, which also undergo constrained flow conditions. This paper considers the relationship between the performance of the HOV and GP lanes by examining speed differential effects as a function of congestion on GP lanes. The research provides evidence of a sympathetic reduction in vehicle speeds in the HOV lane. This is likely explained by the safety concerns of the HOV drivers associated with the potential for vehicles using the congested GP lanes to enter the HOV lane, as well as the safety concerns of...

Transportation Research Part A: Policy and Practice, 2012

We verify that slow speeds in a special-use lane, such as a carpool or bus lane, can be due to both, high demand for that lane and slow speeds in the adjacent regular-use lane. These dual influences are confirmed from months of data collected from all freeway carpool facilities in the San Francisco Bay Area. Additional data indicate that both influences hold: for other types of special-use lanes, including bus lanes; and for other parts of the world. The findings do not bode well for a new US regulation stipulating that most classes of Low-Emitting Vehicles, or LEVs, are to vacate slow-moving carpool lanes. These LEVs invariably constitute small percentages of traffic; e.g. they are only about 1% of the freeway traffic demand in the San Francisco Bay Area. Yet, we show: that relegating some or all of these vehicles to regular-use lanes can significantly add to regular-lane congestion; and that this, in turn, can also be damaging to vehicles that continue to use the carpool lanes. Counterproductive outcomes of this kind are predicted first by applying kinematic wave analysis to a real Bay Area freeway. Its measured data indicate that the site selected for this analysis stands to suffer less from the regulation than will others in the region. Yet, we predict: that the regulation will cause the site's people-hours and vehicle-hours traveled during the rush to each increase by more than 10%; and that carpool-lane traffic will share in the damages. Real data from the site support these predictions. Further parametric analysis of a hypothetical, but more generic freeway system indicates that these kinds of negative outcomes will be widespread. Constructive ways to amend the new regulation are discussed, as are promising strategies to increase the vehicle speeds in carpool lanes by improving the travel conditions in regular lanes.

Transportation Research Record: Journal of the Transportation Research Board, 2015

Transportation Research Record: Journal of the Transportation Research Board, 2010

Over the past decade, several fatal truck-related crashes have occurred on the elevated freeway over the Atchafalaya Basin segment of Interstate 10 in southern Louisiana. In an attempt to reduce the crash rates, the Louisiana Department of Transportation and Development has implemented two policies to regulate the truck traffic on this rural section of freeway. These policies restrict truck traffic to the right lane and reduce the maximum truck speed limit to 55 mph while maintaining passenger car speed limits at 60 mph. To investigate potential relationships between compliance with these policies and crash rates, traffic and crash data were collected for the segment while the policies were in force. Relationships between hourly observations of crash rates and compliance rates were sought at the .05 significance level with multiple linear regression. The traffic characteristics that might affect such a relationship were also incorporated into the regression models. These characteris...