Search

Abstract: The effectiveness of California’s 1171mile High Occupancy Vehicle (HOV) system is assessed using peak hour traffic data from 700+ loop detector stations over many months. The study reaches the following conclusions. (1) HOV lanes are under-utilized: 81% of HOV detectors measure flows below 1400 vehicles per hour per lane (vphpl) during the PM peak hour. (2) Many HOV lanes experience degraded operations: 18% of all HOV miles during the AM peak hour and 32% during the PM peak hour have speeds below 45mph for more than 10% of weekdays. (3) HOV lanes suffer a 20% capacity penalty, achieving a maximum flow of 1600 vphpl at 45mph vs. maximum flow above 2000vphpl at 60mph in general purpose (GP) lanes. (4) HOV lanes offer small travel time savings. The mean savings over a random 10-mile route on an HOV lane vs. the adjacent GP lane is 1.7min and the median is 0.7min; however, HOV travel times are more reliable. (5) Travel time savings do not provide a statistically significant carpooling incentive. (6) A system with one HOV lane and three GP lanes carries the same number of persons per hour as a system with four GP lanes. (7) HOV lanes reduce overall congestion slightly only when the general purpose lanes are allowed to become congested. Despite these findings, HOV facilities can play a useful role in a well-managed freeway system in California. In particular, they can be useful if there is a significant number of buses or vanpools; as a 2-lane HOV/HOT facility, which eliminates capacity loss; and, with efficient metering, as a HOV/HOT bypass at the on-ramps. [Copyright &y& Elsevier]

This paper suggests to use market-based techniques for road traffic coordination. In particular, the question is addressed how to make it more attractive for traffic individuals to follow the suggestions of a coordination system. The presented techniques share a common principle: drivers participate in a voluntary pool of users. They pay into this pool or receive money from this pool according to their usage of the roads. The amount of payment is determined by a predefined electronic trading procedure in which each driver participates by an automated software unit representing the individual driver’s intentions. This paper compares three different trading mechanisms. The presented techniques are advantageous for the applications dynamic route assignment and individual road clearance. Compared to traditional traffic demand management systems, market-based techniques are expected to have a higher degree of flexibility and adaptability. Another advantage is that market-based techniques are independent of a prior set-up of traffic models and analyses. [Copyright &y& Elsevier]

The aim of the paper is to evaluate the performance of a new strategy which is able to control dynamic route guidance (DRG) systems, mainly in urban road networks. The purpose of this strategy is to achieve dynamic user equilibrium in the network, even in abnormal network conditions, for example when there is an unexpected increase in traffic volume. It is based on feedback concept and it reacts to the traffic conditions observed in real time by adopting a decentralized structure.A series of experiments was performed, by means of a traffic micro-simulator, in a section of an urban road network. In the situations examined, the results seem to be quite positive. The analyses of the link level show that all of the various travel alternatives to reach the destination become more advantageous for users if DRG devices become more widespread among vehicles. In some cases we observe that the strategy succeeds in maintaining the possible alternatives in equilibrium conditions, by distributing users among the feasible turns. At no point in our investigations do we observe an unstable behaviour of the system, even when the number of vehicles fitted with a DRG device increases. [Copyright &y& Elsevier]