This paper aims to evaluate and compare the effects of different methods of ramp metering on the operational conditions of traffic flow at three levels: the network level (including the freeway and its connected ramps), the entrance ramp, and the upstream segment of the entrance. To achieve this aim, one of the most important urban freeways in the metropolis of Isfahan was selected. The traffic...

To ensure higher Level of Service (LoS) at urban motorways, new traffic control concepts are being applied since in most cases there is no available space for infrastructural build-up. For urban motorways, the mostly used control methods are ramp metering combined with additional control methods like variable speed limit control (VSLC). This paper gives a review of the current ramp metering app...

Ramp metering has been recognized as an effective freeway management strategy to either avoid or ameliorate freeway traffic congestion by limiting access to the freeway. California has applied ramp metering widely in major metropolitan areas. Currently, California has three major ramp metering systems: San Diego Ramp Metering System (SDRMS), Semi-Actuated Traffic Management System (SATMS), and ...

Ramp metering is an effective, viable, and practical strategy used to manage freeway traffic. It is a proven freeway management technique as various forms of ramp control have been in place since the 1960s in the Chicago, Detroit, and Los Angeles areas. Due in part to the success of these early applications, ramp metering has received increased emphasis in recent years under the umbrella of adv...

Ramp metering has been broadly accepted and deployed as an effective countermeasure against both recurrent and non-recurrent congestion on freeways. However, many current ramp metering algorithms tend to improve only freeway travels using local detectors' inputs and overlook the negative impacts on local streets. This may generate two problems: 1) the optimal local settings may not result in a ...

One of the major criticisms of ramp-metering has been the delay caused on the ramps because of the queues created by ramp control strategies. However, recently, several researchers proposed strategies that explicitly take into account ramp queues when determining metering rates. In this paper, an isolated “feedback” based ramp-metering strategy using modeling is presented. In addition to the re...

The general purpose of this study is to develop both efficient and equitable freeway ramp control strategies. Measures of efficiency and equity for ramp meters are defined and applied to data collected in the Twin Cities ramp metering shut-off experiment. A trade-off between efficiency and equity is evident from the results of data analysis. A new time-dependent optimization program for the glo...

This study presents a real-time crash prediction model and uses this model to investigate the effect of the local traffic-responsive ramp metering strategy on freeway safety. Safety benefits of ramp metering are quantified in terms of the reduced crash potential estimated by the real-time crash prediction model. Driver responses to ramp metering and the consequent traffic flow changes were obse...

Ramp meters in the Twin Cities have been turned off for eight weeks in fall 2000 in an experiment testing their effectiveness. This chapter analyzes the data collected during the experiment on several representative freeways during the afternoon peak period. Several performance measures for ramp metering including mobility, equity, consumers’ surplus, productivity, accessibility, and travel tim...

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...