Graduation Year

2011

Document Type

Dissertation

Degree

Ph.D.

Degree Granting Department

Civil and Environmental Engineering

Major Professor

John Lu

Keywords

Cross Road, Operational Analysis, Safety Analysis, Simulation, TSIS-CORSIM

Abstract

This research focuses primarily on the analysis of exit ramp performance related to safety and operations. The safety analysis focuses on the impacts of different exit ramp types for freeway diverge areas and different factors contributing to the crashes that occur on the exit ramp sections. The operational analysis is based mainly on simulations by TSIS-CORSIM. Different ramp effects and guidance for selecting optimal exit ramp type are concluded. Issues related to ramp sections and crossroad sections are also demonstrated. Minimum ramp length and minimum distance between ramp terminal and downstream or upstream intersections are calculated. The operational analysis was conducted to determine different ramp effects and to provide guidance for selecting optimal exit ramp type.

Comparisons of the operational performance of different types of exit ramps are made to present a method for choosing the optimal one. Some methods of evaluation (MOEs) are used to approach this objective, such as number of lane changes, average speed, delay time, etc. Data collection at 24 sites in Florida was conducted, and traffic simulations by TSIS-CORSIM were applied for analysis. Mathematical models were built to evaluate different impacts of these ramps based on simulations. All impact analysis is concluded to summarize a model for optimal exit ramp selection. In addition to ramp type evaluation and selection, issues related to ramp section and crossroad section are demonstrated. Minimum ramp length and minimum distance between ramp terminal and downstream or upstream intersections are calculated.

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