To increase operational efficiency, reduce congestion, and meet federal requirements concerning truck size and weight limits, the California Department of Transportation (Caltrans) is exploring new plans and feasible projects designed to increase enforcement and reduce pavement damage due to overweight trucks. Installation of Weigh-in-motion (WIM) systems or Virtual Weigh Station (VWS) by Caltrans will provide information to the California Highway Patrol (CHP) that they can use to better enforce commercial vehicle laws in those areas. To support the effective deployment of WIM/VWIM...
This report addresses Task S of the Intersection Decision Support (IDS) project funded by Federal Highway Administration (FHWA) and Caltrans. The objective of Task S is to evaluate and select Commercially-Off-The-Shelf (COTS) and emerging technology products that could eventually be deployed at intersections as part of the IDS system. Many sensors were considered and every plausible detection technology was reviewed for this task. The emphasis was on finding sensors that detect and track vehicle movements.This effort started with establishing a background and general guidelines for what...
This report characterizes the statistical performance of the magnetic nails concept for estimating the positions of vehicles within their marked lanes. The report also presents a mathematical model for sensor noise due to the distortions of the earth field by regular patterns of ferrous reinforcing bars in the pavement.
This report discusses the issues investigated during the first phase of a project which focuses on the development of a simulation program which will allow the study of platoon dynamics in both nominal and emergency scenarios. Preliminary issues include collision detection between the vehicles within the platoon and determining the platoon's post-crash behavior. A two-dimensional vehicle has been developed to addresses these issues. The overall simulation program includes individual modules that supply control input force, aerodynamic drag force, and road-tire interaction forces....
A new technology known as Virtual Weigh Stations (VWS) is intended to transform data-collecting weigh-in-motion (WIM) sites to weight enforcement mechanisms. This study investigates the possible benefits to the highway pavements in California from potential use of VWS. The investigation proceeded in two steps: (1) determining the damage currently caused by overweight trucks and (2) modeling the potential pavement life saved with VWS. The data used for analysis is from the California Department of Transportation (Caltrans) WIM database.
Trucking productivity can be significantly increased by moving freight with longer combination vehicles (LCVs). However, LCV operations not only raise safety concerns for the surrounding traffic and the LCV drivers themselves but also can damage roadways and bridges not equipped to support the operations. All the discussion about truck size and weight limitations or about the pros and cons of LCV operations is predicated on the use of conventional tractors and trailers. We however observed that a root cause of several major issues associated with LCV operations is the problem of off-...
This report documents findings from analysis of traffic collision data from sites that display high collision rates only under wet pavement conditions. These sites were selected using Caltrans safety engineers’ field reports, Wet Table C “investigation required” locations, and a new approach called Continuous Risk Profile (CRP).The geometric features at the sites were studied via field visits and review of as-built plans. Rapid spatial changes (i.e., vertical and horizontal curve in short distance), narrower lane width, lack of median, and wider total freeway width were some of the notable...
Bus Rapid Transit (BRT) has the potential to improve mass transit service and contribute to reduced traffic congestion in urban areas. To achieve this improvement in service BRT will require the use of dedicated bus lanes together with lane assist and precision docking (LA/PD) to accelerate the passenger boarding process. Using this approach, BRT lanes can be reduced somewhat in width. However, such a reduction will result in increased channelization of traffic which in turn can lead to a more rapid development of pavement distress. With today’s improved pavement engineering technology, it...
Current traffic travel time estimates are largely based on road sensors embedded in the pavement. Today technical developments in cellular positioning and the spread of wireless phones provide the opportunity to track cell phone equipped drivers as traffic probes. The Federal Communication Commission Phase II mandate for Enhanced-911 (E-911) requires that wireless carriers must provide the location of a 911 wireless call by October 1, 2001 to the Public Safety Answering Point (PSAP), within approximately 125 meters, or under one-tenth of a mile in the majority of situations. The motivation...
This report presents a review of alternative techniques to determine the presence of ice on road surfaces. It examines techniques ranging from passive, in-pavement technologies, to different remote sensing techniques. The author presents the Polarized Reflectance Infrared Signature Method (PRISM) technique which uses differences in measured near infrared reflectance between ice, water and dry road due to absorption, in addition to the effect of polarization to discount the contribution of specutacular reflectance off the front surface.
