Development of Breakdown Probability Models for Rural Freeway Work Zones Using Field Data and Simulation

Abstract

The current state of the National Highway System often necessitates that agencies interrupt normal traffic operations for maintenance and capacity improvements. With nearly 9 million lane-miles of public roadway and an economy driven by the automobile, these interruptions are inevitable, but the significant safety and mobility impacts associated with queueing at freeway work zones are mitigable. The current methodology in the 6th edition of the Highway Capacity Manual is a vast improvement over historical work zone capacity guidance, but approaches the issue differently than research suggests agencies and practitioners should. Namely, a capacity defined by the mean queue discharge rate is deterministic and fails to account for the stochastic nature of traffic flow and breakdown. This thesis addressed these core issues by calibrating and validating a VISSIM model for a rural freeway work zone lane closure and exploring the probability of queue formation as a function of traffic volume, truck percentage, and lane closure side. The results were combined to form a capacity analysis tool that may be used by agencies and practitioners to make data-driven planning, design, and operations decisions at rural freeway work zones. The methodology applied herein may also be extended to freeway facilities exhibiting different geometric, traffic, and environmental characteristics.