The Highway Capacity Manual is a major reference for evaluating the capacity and quality of service of road facilities. However, it holds the assumption that lanes perform equally, which can result in inaccuracies in performance estimation. The main purpose of this research is to develop a series of models for estimating flows and speeds by lane for various types of freeway segments, including basic, merge, and diverge types. These models consider the demand-to-capacity ratio, the presence of trucks, grade, and the presence of upstream and downstream ramps. To predict lane performance...
This paper describes the methodology and findings for developing improved passenger car equivalent (PCE) factors for trucks at signalized intersections on the basis of field data and simulation modeling. The Highway Capacity Manual 2010 (HCM 2010) assumes a single PCE value of 2.00 for trucks at traffic signals. The proposed truck PCE values are sensitive to the proportion of trucks, truck type, and intersection’s approach grade. It is recommended that the current HCM 2010 approach of computing the heavy vehicle and grade effects on saturation flow rates independently be replaced with a...
An algorithm for real-time estimation of truck traffic in multilane freeways was proposed. The algorithm used data from single loop detectors--the most widely installed surveillance technology for urban freeways in the United States. The algorithm worked for those freeway locations that have a truck-free lane and exhibit high lane-to-lane speed correlation. These conditions are met by most urban freeway locations. The algorithm produced real-time estimates of the truck traffic volumes at the location. It also can be used to produce alternative estimates of the mean effective vehicle length...
Freeway service patrols (FSPs) are a popular means of incident management and control. The authors address the question of the correct placement of FSP tow trucks as a scarce resource allocation problem. They present a methodology for determining where to place FSP tow trucks so as to maximize the expected reduction in congestion. They illustrate this approach using the I-880 database.
Greenhouse gases (GHG), the gases that cause climate change, are a major global concern. In the transportation sector, GHG reduction initiatives focus on passenger travel over goods movement, despite increasing freight demand and related emissions. California, with its recent GHG reduction legislation and large freight centers and corridors, provides a unique case study to evaluate the introduction of an alternative freight mode. Short sea shipping (SSS) offers a low GHG emission alternative to overland modes such as heavy-duty trucks. Analysis shows that this service is justifiable from a...
California is one of the largest producers of perishable produce in the world. This sector supports a large transportation industry that handles the exports of these goods. Starting from the 1950’s, the export of produce has gradually shifted modes from rail to truck. This project builds on the initial work from the “Rail and the California Economy” project by examining the potential of shifting the movement of perishable produce in California from truck to rail. The final report provides a review of the state of the California rail system in terms of perishable produce transport and where...
Partially/fully self-driven trucks in platoon configurations promise to increase transport efficiency, reduce fuel consumption/gas emissions and improve road safety through the use of connectivity technologies and automated driving support systems. However, truck platooning means the introduction of new types of loads on pavements which are characterised by: multiple loads, generated by the multi-axle configurations of the different trucks forming the platoon, traffic channelisation by the reduction of the lateral deviation of the trucks, and reduced inter-truck time gaps, which may reduce...
The reduced distances that can be achieved by truck platooning allow the reduction of drag resistance and therefore fuel consumption, gas emissions and costs for the transporters. However, this new way to configure trucks represents a new type of loading for pavement structures. This new type of loading is characterized by: (1) multiple load solicitations in a reduced period of time, (2) reduced inter-truck time gaps/distances, and (3) reduced lateral deviation of the vehicles forming the platoon, and therefore a more localized pavement damage. This paper investigates these effects and...
The impacts of the Loma Prieta earthquake on Bay Area trucking firms, based on a combination of in-depth interviews and a random survey, are reported. The earthquake's primary impact on truckers derived from the closure of major roadway facilities, which necessitated circuitous routings and increased congestion on the facilities that remained open. The vast majority of truckers rated the impacts from increased congestion and circuitous routings as moderate or severe. Other impacts affecting substantial proportions of truckers involved communication and dispatching efficiency. The most...
