The Hampton Roads Bridge-Tunnel (HRBT) serves as a critical link for regional mobility and economic activity in Hampton Roads. 

Significant traffic congestion occurs in and around the HRBT. Although several sources of this congestion are known, including capacity issues, over-height vehicles and incidents, there still is a need to identify specific triggers and to quantify the spatial and temporal characteristics.

This study will identify specific bottleneck locations responsible for recurring congestion in and around the HRBT and determine the contributing geometric, traffic, driver-behavior, or traffic-control factors. It also will estimate the impact of over-height vehicles and other incidents on nonrecurring congestion in the tunnel area.