As an efficient traffic control strategy to ameliorate freeway traffic congestion, ramp metering has been successfully applied in the US. However, the applicability and effectiveness of a ramp-metering strategy are required to be investigated during the preimplementation phase in order to ensure the success of the implementation. The use of traffic simulation models can provide a quick and cost...

We apply model predictive control to optimally coordinate variable speed limits and ramp metering. The basic idea is that speed limits can increase the (density) range in which ramp metering is useful. For the prediction we use a slightly adapted version of the METANET traffic flow model that takes the variable speed limits into account. The optimal control signals aim at minimizing the total t...

During the last century, there has been considerable economic growth and development of cities around the world. The growth has led to an expansion of car-ownership and ultimately increased congestion of the road network. Traffic engineers and transport planners have attempted to mitigate the consequences of congestion of motorways and freeways using a number of techniques. One of which has bee...

The paper characterizes the behavior of the cell transmissionmodel of a freeway, divided intoN sections or cells, each with one on-ramp and one off-ramp. The state of the dynamical system is theN-dimensional vector n of vehicle densities in theN sections. A feasible stationary demand pattern induces a unique equilibrium flow in each section. However, there is an infinite set—in fact a continuum...

This paper formulates the ramp metering control problem as a real-time feedback control problem. The development is shown by modeling freeway sections, and hence the results are immediately applicable to isolated ramp metering problems. The ideas presented in this paper can be utilized to develop coordinated ramp metering feedback control techniques. Three different forms of the formulation for...

The recently developed traffic-responsive feedback control strategy HERO (HEuristic Ramp metering cOordination), that coordinates local ramp-metering actions in freeway networks, was implemented at the M1/M3 Freeway in Queensland, Australia. HERO employs an extended version of the feedback regulator ALINEA at the local level. HERO outperforms uncoordinated local ramp metering and approaches the...

We develop an anticipative model-based predictive traffic control approach for ramp metering in freeway traffic networks. If ramp metering is implemented in a freeway network with alternative routes, traffic can spontaneously re-route due to the response of the drivers to the applied control actions. Although spontaneous re-routing can have a significant influence on the resulting traffic situa...

To control the traffic flows near on-ramps and off-ramps, ramp metering installations can be used. We compare on-ramp metering and off-ramp metering, with respect to queue forming and total time spent. Both control measures are used to improve traffic flow on freeways, and both have influence on the route choice of the drivers. Although the two measures are very similar, there are some major di...

Unlimited access to a motorway network can, in overloaded conditions, cause a loss of capacity. Ramp metering (signals on slip roads to control access to the motorway) can help avoid this loss of capacity. The design of ramp metering strategies has several features in common with the design of access control mechanisms in communication networks. Inspired by models and rate control mechanisms de...

Part I: Modeling, Estimation, and RampMetering Control of Freeway Traffic Themain objective of Part I is to develop improved algorithms for freeway on-ramp metering control. Toward this end, two macroscopic traffic models are first introduced and analyzed. The first is a modification of the cell transmission model (CTM) developed by Daganzo. This modified CTM uses cell vehicle densities as its ...