The capacity of a freeway is traditionally considered as a constant value in traffic engineering. In reality, capacities vary according to external conditions such as dry or wet road surfaces, daylight or darkness, and to the prevailing travel purpose of drivers on the freeway. Even under constant external conditions different capacities can be observed on freeways because of variations in driv...

A new ramp metering strategy implemented on the Twin Cities freeway system to reduce ramp waiting times was evaluated through microsimulation of freeway activity. The study compared Stratified Ramp Metering strategy with the previous Zone Metering Strategy and with no control strategy. Comparison with Zone, which was designed to favor freeway flow, showed the new strategy succeeded in greatly r...

Bottlenecks are key features of any freeway system and represent the emerging location for recurrent and non-recurrent traffic congestion. In Oregon, a freeway data archive known as PORTAL records volume, occupancy, and speed measurements from over 600 freeway locations every 20 seconds. This archive has enabled development of online freeway performance and reliability analysis tools. This pape...

An integrated modeling of freeway traffic is developed, whose implementation in an uniform computer–aided simulation model facilitate comparative evaluation and systematic coupling of several traffic simulations, traffic controls, traffic measurements and traffic scenarios. The integrated modeling of freeway traffic is a basic mapping of freeway networks, control methods, measurements and diffe...

Roads present formidable barriers to dispersal. We examine movements of two highly mobile carnivores across the Ventura Freeway near Los Angeles, one of the busiest highways in the United States. The two species, bobcats and coyotes, can disappear from habitats isolated and fragmented by roads, and their ability to disperse across the Ventura Freeway tests the limits of vertebrates to overcome ...

The purpose of this study was to determine the influence of ramp spacing on the traffic flow characteristics on the Atlanta Freeway System and city streets influenced by the freeway. Timelapse photography was used to collect data at four study locations on the freeway. Speed and delay studies were also made on the freeway and surface streets during ramp closure periods and during normal operati...

The objective of this study was to assess the effectiveness of freeway lighting. To achieve this, a case study on traffic accident characteristics was conducted that utilized a suburban freeway area west of Frankfurt, Federal Republic of Germany, between 1972 and 1981. The study revealed that (a) the effects of lighting on suburban freeway accident rates was positive--there was a reduction in a...

Real-time traffic flow operation condition of freeway gradually becomes the critical information for the freeway users and managers. In fact, electronic toll collection (ETC) transaction data effectively records operational information of vehicles on freeway, which provides a new method to estimate the travel speed of freeway. First, the paper analyzed the structure of ETC transaction data and ...

Bottlenecks are key features of any freeway system and their impacts are of increasing importance as congestion worsens in urban areas. In Oregon, a freeway data archive known as PORTAL records measured count, occupancy, and speed data from over 600 locations at 20-second intervals. This archive has enabled development of online freeway performance and reliability analysis tools. This paper des...

This paper formulates the problem of real-time estimation of traffic state in freeway networks by means of particle filtering framework. A particle filter (PF) is developed based on a recently proposed speed-extended cell-transmission model of freeway traffic. The freeway is considered as a network of components representing different freeway stretches called segments. The evolution of the traf...