Selection for optimal exit ramp type on Florida's freeways based on operational analysis

Abstract

In the State of Florida, several types of exit ramps are used, including single-lane exit ramp with a taper, single-lane exit ramp without a taper, two-lane exit ramp with an optional lane, and two-lane exit ramp without an optional lane. Drivers exiting freeways need to make maneuver decisions (lane change, lane merge, and decelerate) prior to exit ramps in order to access cross roads at interchanges. Different exit ramp types lead to varying driving maneuvers when exiting, affecting the operational and safety performance on freeways. Based on the facts, there are several issues that need to be addressed in selecting the most optimum types of freeway exit ramps. This article mainly focuses on the comparison of operational performances of different ramp types and tries to present a method for choosing the optimal one. A data collection of 24 sites in Florida were conducted, and traffic simulations by Traffic Software Integrated System: Corridor Simulation were employed. Mathematical models were built to evaluate impacts of these ramps based on simulations. And an analytical hierarchy process method was applied to assign significance weight for all selected measures of effectiveness in terms of Florida questionnaire. Finally, an aggregate numerical evaluation was provided according to calculated data.