Dedicated Lanes, Tolls and ITS Technology (original) (raw)
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The merits of separating cars and trucks
Journal of Urban Economics, 2008
Truck-only lanes and tollways are under study as tools to combat road congestion, enhance safety and reduce other external costs of road traffic. This paper investigates the potential benefits from separating cars and trucks onto different lanes or routes while treating road infrastructure as given. The benefits are found to depend on several factors: the relative volumes of cars and trucks, the congestion delay and safety hazards that each vehicle type imposes, values of travel time for each type, and lane capacity indivisibilities. The optimal assignment of vehicles to road capacity can be supported using tolls that are differentiated by vehicle type and lane. Lane access restrictions usually cannot support the optimum and may well provide no benefit at all. Creating a toll lane for one vehicle type is generally more effective. The benefits of all forms of intervention are sensitive to whether the proportions of cars and trucks are commensurate with lane capacities.
The economics of truck toll lanes
2007
Truck-only lanes and tollways have been promoted as a way to combat road congestion, enhance safety and reduce pavement damage. This paper explores one aspect of truck lanes by considering whether there are advantages in separating cars and trucks. The benefits of vehicle separation are found to depend on several factors: the relative volumes of cars and trucks, the congestion delay and safety hazards that each type of vehicle imposes, values of travel time for cars and trucks, and lane capacity indivisibilities. The optimal assignment of vehicles to lanes can be supported using tolls that are differentiated by vehicle type and route. By contrast, lane access restrictions generally cannot support the optimum and may provide no benefit at all.
Economic Feasibility of Exclusive Vehicle Facilities
Transportation Research Record, 1991
A microcomputer program called "exclusive vehicle facilities" (EVFS) that determines the economic feasibility of separating light vehicles from heavy vehicles on a given section of controlled-access highway by designating existing lanes and constructing new lanes to be used exclusively by light or heavy vehicles is described. On the basis of user inputs to a spreadsheet user interface, EVFS calculates the net present value, benefit-cost ratio, and other performance measures of the alternative exclusive vehicle facility specified. The three possible lane use policies allowed within EVFS are mixed-, light-, and heavy-vehicle lanes. EVFS accounts for the following potential benefits or cost savings both for person and for freight travel: (a) travel time savings; (b) vehicle operating cost savings; (c) accident cost savings (fatalities, injuries, and property damage), because of less severe accidents by separating light and heavy vehicles; and (d) queuing delay savings because...
Economic and Financial Feasibility of Truck Toll Lanes
Transportation Research Record: Journal of the Transportation Research Board, 2003
The economic and financial feasibility of heavy-truck toll lanes was analyzed. This research expanded the line of inquiry of previous researchers by analyzing toll lanes for exclusive use by heavy trucks (i.e., large size and capacity). Implementation of such a toll system was studied relative to productivity changes, toll-lane fees, users' travel time and vehicle operating cost savings, and impact on infrastructure costs. The economic benefits were estimated using the Highway Design and Maintenance Standards Model developed by the World Bank. The analyses, complemented with sensitivity analyses of key variables, indicate that heavy-truck lanes are economically and financially viable.
Dual influences on vehicle speed in special-use lanes and critique of US regulation
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.
Another View of Truck Lane Restrictions
Transportation Research Record: Journal of the Transportation Research Board, 2004
As truck volumes on U.S. highways continue to increase, both elected officials and members of the general public often look to the use of lane restrictions for large trucks as a means to increase operating efficiency and highway safety. In the past, research has offered little evidence that either safety or efficiency is positively affected by widespread use of this practice. Another view of truck lane-use restrictions on high-speed, limited-access facilities is offered. To determine the effects of lane-use restrictions, scenarios that varied traffic characteristics such as volume, grade, percentage of trucks, and the presence of entrance and exit ramps were developed with the VISSIM model. In each scenario traffic along the model freeway segment was monitored to determine the effect of the lane-use restrictions by comparing values of various traffic measures from a model run first without and then again with truck lane restrictions. As in past research efforts, the implementation o...
Spatiotemporal effects of segregating different vehicle classes on separate lanes
2009
Spatiotemporal analysis of real freeway traffic reveals that carpool lanes are not as damaging as previously reported. To the contrary, the analysis unveils a surprising benefit of carpool lanes that should be even greater when special lanes are used to segregate very different vehicle classes, such as buses and cars. The paper pursues this finding and shows how reserving lanes on freeways and city streets for bus-use only can favorably affect not just buses, but also cars.
Deploying Lanes for High Occupancy Vehicles in Urban Areas
Uc Berkeley Center For Future Urban Transport a Volvo Center of Excellence, 2007
Simulations and field experiments in previous works suggest that a freeway's general purpose lanes (those not dedicated to high occupancy vehicles) discharge vehicles from bottlenecks at an equal or higher average rate when one of the lanes is devoted to high occupancy vehicles than when it is not. This result was used in these previous works to develop formulae for the total discharge rate of bottlenecks, with and without dedicated lanes, as a function of the percentage of high occupancy vehicles in the traffic stream. This present paper extends these ideas by examining the effect of dedicated lanes on the density of traffic queues. We find that an underutilized dedicated lane reduces a queue's density (in vehicles per km of freeway) when the downstream flow of both high occupancy and low occupancy vehicles is the same in both scenarios and exogenously determined; e.g., as would happen if the queue's service rate is dictated by recurrent downstream congestion. A formula is given; and the reduction in density turns out to be small if the underutilization is small. Reductions in queue density without changes in bottleneck flows or traffic demand imply spatially longer queues, and this could be problematic. The paper also shows that the extra space consumed by a queue adjacent to a dedicated lane can contribute significantly to congestion, but only if heavily traveled routes that do not go through the bottleneck pass through this extra space. To quantify this effect, the paper analyzes dedicated lanes on multi-ramp freeways and beltways. Formulae are given for the changes in the people-hours and vehicle-hours of travel due to dedicated lanes both, when there is uncongested freeway space upstream of the queue for it to expand, and when there is not. The recipes are based on readily observable data and can be used to evaluate existing and planned installations of dedicated lanes. Building on these formulae, the paper finally presents qualitative principles that can be used to plan city-wide systems of both, high occupancy vehicle lanes on freeways and dedicated bus lanes on surface streets.
Highway expansion projects in large metropolitan areas are usually contentious. What are the full effects of highway capacity gains and who wins and who loses? This research elaborates our earlier network impact modeling work in two important directions. First, we extend our modeling capability to include highway lanes that are tolled. Second, we apply the new model to an important prototype application, the (recently) private 10-mile segment of California SR91. The possible widening of this route via extra tolled or extra general-purpose lanes has been the subject of considerable controversy. We show that our approach can shed light on key elements of such controversies and, thereby, possibly reduce political conflict and misunderstanding. We also show that whereas congestion tolls are widely presumed to be efficient, the efficiency outcomes are complex when only a very small part of the network is tolled.
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.