Exploratory Spatial Analysis of Expressway Ramps and its Effect on Route Choice

Abstract

This research is based on the analysis of an origin-destination survey of users of Central Florida’s expressway system. It presents an initial investigation of the drivers’ choice in accessing/exiting the ramps of the system. The implications for route choice and spatial behavior are also addressed. The results showed that the distance traveled to access or after exiting a ramp does not depend only on the spacing between ramps, but on several factors, such as the trip purpose, vehicle occupancy, driver’s income level, and E-Pass use [whether the vehicle is equipped with an electronic toll collection system (ETC)]. A significant result also was that there is considerable difference in the drivers’ choices between entering and exiting the expressway. There is an indication that drivers prefer to access the expressway at shorter distances from their origins, but they are willing to travel longer distances to their destinations once they exit the expressway. A simplistic route choice analysis also presents some insights into the route choice paradigm. Route choice was found to be a function of several factors including the travel time, toll cost, and simplicity of the route (represented by the number of different roadway segments). The existence of a guide sign directing the driver to his/her destination also had an important impact on route choice, particularly for nonfamiliar travelers. Another factor, specific to toll roads, is the toll payment facility and toll payment method. Drivers of vehicles equipped with the ETC system (E-Pass), in a certain scenario, preferred a different route from drivers with no E-Pass. Finally, a multinomial logit route choice model was developed and illustrated the significance of several factors including the direction of travel, frequency of making the trip, age, residency, and E-Pass use on the likelihood of choosing a certain route. This research confirmed findings from previous work and the literature that route choice is a function of multiple factors and not only travel time or distance.