This paper develops an analytical framework for ramp metering, under which various ramp control strategies can be viewed as ramifications of the same most-efficient control logic with different threshold values, control methods, and equity considerations. The most-efficient control logic only meters the entrance ramps nearest critical freeway mainline sections so as to eliminate freeway interna...

This paper presents a feedback control design for a coordinated ramp metering problem. We design an optimal traffic allocation scheme for ramps based on Godunov’s numerical method and using distributed-diffusive model. Most of the previous work for designing feedback control for ramp metering is based on either the discretized linear methods such as ALINEA or nonlinear methods based on the traf...

Freeways were originally conceived to provide virtually unlimited mobility to road users. However, the continuous increase in car ownership and demand has led to a steady increase (in space and time) of recurrent and nonrecurrent freeway congestion, particularly within and around metropolitan areas. Freeway congestion causes excessive delays, increases fuel consumption and environmental polluti...

During recent decades, traffic demand has overtaken the overall capacity of existing highway and freeway networks, causing traffic delays and negative environmental impacts. Consequently, innovative traffic control strategies have been developed to improve network performance and they have proved to be effective in delaying or preventing congestion. Dynamic microsimulation models are natural co...

This paper examines the conditions for which ramp metering can be bene®cial to the overall system in terms of travel time savings for a simple trac corridor that consists of a freeway and a set of parallel arterials connected by entrance ramps. The focus is on analyzing state and control relationships to arrive at general analytical results regarding optimal metering policies, rather than on e...

A method is presented to divide the total congestion delay in a freeway section into six components: the delay caused by incidents, special events, lane closures, and adverse weather; the potential reduction in delay at bottlenecks that ideal ramp metering can achieve; and the remaining delay, due mainly to excess demand. The fully automated method involves two steps. First, the components of n...

16. Abstract Diamond interchanges and their associated ramps are where the surface street arterial system and the freeway system interface. Historically, these two elements of the system have been operated with little or no coordination between the two. One drawback of operating the ramp-metering system and the diamond interchange system in isolation is that traffic from the ramp, particularly ...