We present a method for automated, empirical calibration of freeway traffic flow characteristics. The method uses 5-min flow and density values for a section of freeway and rapidly and reliably estimates key parameters such as free flow speed, capacity, critical density, congestion wave speed and jam density, which are key inputs to many macroscopic traffic simulation models. The method consist...

This research studies freeway ramp merging phenomena under congested traffic situation via a Driving Simulator (DS). The main objectives of this study were to initially develop a traffic simulation, which evaluates the capacity of merging section relevant to the geometric design and the flow condition. Furthermore, to form a pilot system of the DS combined with the simulation, from which the dr...

Freeway capacity decreases at sags due to local changes in car-following behavior. Consequently, sags are often bottlenecks in freeway networks. This article presents a microscopic traffic model that reproduces traffic flow dynamics at sags. The traffic model includes a new car-following model that takes into account the influence of freeway gradient on vehicle acceleration. The face-validity o...

This work describes a micro simulation program that is developed to study freeway ramp merging phenomena under congested traffic conditions. First, the results of extensive macroscopic and microscopic studies are used to establish a model for the behaviour of merging drivers. A theoretical framework for modeling the ramp and freeway lag driver acceleration-deceleration behaviour is then present...

Although transit or road capacity increases are historically very common subjects of economic analysis, the implementations of intelligent transportation systems (ITS) strategies have been receiving increasing attention as resources for capacity expansion become increasingly scarce. There exists a strong business case for lower cost strategies to more efficiently deliver transportation in ways ...

When freeway traffic flow approaches capacity, minor disturbances or perturbations can cause unstable traffic streams to break down into queued or bottleneck conditions with the accompanying heavy congestion costs. As the traffic volume at which flow breaks down is uncertain, this research utilizes a stochastic capacity model to estimate congestion costs in terms of delays, fuel, and emissions....

This study aims to determine whether ramp meters increase the capacity of active freeway bottlenecks. The traffic flow characteristics at twenty-seven active bottlenecks in the Twin Cities have been studied for seven weeks without ramp metering and seven weeks with ramp metering. A methodology for systematically identifying active freeway bottlenecks in a metropolitan area is proposed, which re...

On-ramp merging areas are essential parts of freeways. The behavior vehicles is the main factor affecting continuity freeway traffic flow, which determines capacity line. With development innovative car technology, ACC technology has been widely used in actual vehicles. At same time, public’s demand for freeway-speed improvement increasing. However, evaluative research on freeway-speed-improvem...