01124314

Component

Freeway ramp metering has been used in a number of U.S. cities since the 1960s in order to improve traffic flow on urban freeways, increase freeway speeds, reduce overall travel times, and improve travel time consistency. Their purpose is to regulate the rate at which vehicles are allowed to enter the freeway at the entrance ramps. Despite their benefits, ramp metering strategies have been controversial and have not been used in many states including the state of Alabama. In this study, the IDAS sketch-planning software is used to develop estimates of benefits and costs from the implementation of ramp metering along selected interstate freeways in the Birmingham area. Both fixed and traffic actuated ramp metering strategies are being evaluated. An advantage of using IDAS is that it implements the modal split and traffic assignment steps associated with a traditional planning model. As a result it is capable of capturing the changes in modal, route, and temporal decisions of travelers resulting from ramp metering implementation. Moreover, this study assesses the potential impact of ramp metering on traffic operations using microsimulation modeling. More specifically, the CORSIM simulation model is employed to simulate traffic conditions along major interstate corridors in Birmingham, Alabama with and without ramp metering. Various types of ramp metering strategies are assessed including fixed, demand/capacity, speed control, multiple-threshold occupancy control and ALINEA control metering. Simulation outputs and animations are reviewed to determine the impact of the strategy on network operations. Potential spillback effects on neighboring arterials are also considered and recommendations are offered on effective ways to alleviate this problem. The results from the case study are used to determine if ramp metering is a vital option for the interstate corridors in the Birmingham region and if so, identify the type of ramp metering option that best suits the local needs, along with associated benefits and cost from potential deployment.

01033979

English

13p

2006

1st International Symposium on Freeway and Tollway Operations

DVD

Figures (4) ; References (3) ; Tables (5)

Benefits; Case studies; Costs; Freeway operations; Microsimulation; Ramp metering; Sketch planning

CORSIM (Traffic simulation model); IDAS (Computer program)

Spillback effects (Traffic)

Birmingham (Alabama)

Highways; Operations and Traffic Management; I73: Traffic Control

TRIS, TRB

Mar 19 2009 8:26AM

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