NORFOLK — The Hampton Roads Bridge-Tunnel serves as a critical transportation link for economic activity in Hampton Roads, but it is also a source of significant recurring congestion.
The bridge-tunnel carries almost 100,000 vehicles on a typical weekday. Large semitrailers are a fraction of this volume – at about 2 percent – but they pose a major challenge to daily operations.
The HRBT capacity is significantly less than the typical capacity of a two-lane freeway segment due to several geometric restrictions like narrowing of the roadway at the tunnel entrance, horizontal and vertical curves, and variation in driver behavior while traveling through the tunnels. In addition, incidents cause disruptions to the traffic flow, further exacerbating the conditions at the already congested corridor.
In particular, over-height trucks cause frequent stoppage of the traffic since the tunnel clearance in the older westbound direction is lower than the newer eastbound tube, 13′ 6″ compared to 14′ 6″ in the eastbound direction. In order to turn around, an over-height truck at the tunnel islands, traffic in both directions is interrupted or stopped.
To address the issue, a $140,000 VDOT grant will fund an evaluation of the effectiveness of various mitigation strategies by a team of Old Dominion University researchers led by Mecit Cetin, associate professor of civil and environmental engineering.
VDOT is in the process of installing an additional over-height detection sensor and new alert signs before the westbound inspection station. This installation was completed on Nov. 2. Research is needed to evaluate the impacts of this new system. Research is also needed to fully understand and document the reasons behind the violations, and potential short-term and long-term strategies to minimize truck turnarounds at the islands and evaluate their applicability to the HRBT corridor.
This proposed research will result in a final report documenting:
- important characteristics of the violators (e.g., by trucking companies) and trends in violation rates based on the archived data
- the benefits and impacts of the new over-height vehicle detection system to be installed at the HRBT corridor
- the major reasons behind over-height violations and characteristics of frequent violators before and after installation of the over-height system.
“In this VDOT project, we are going to investigate how these over-height violations could be reduced or ideally eliminated,” said the project’s lead investigator Mecit Cetin. “We are going to evaluate the effectiveness of new and larger warning signs, and survey truck drivers to better understand why they proceed through the corridor despite the warning signs in the upstream.”
In September, 727 over-height vehicles going westbound were stopped. Of those, 381 made it to the 15th View detection station and another 346 were turned around at the island, a spokesperson for VDOT said. In August, the number of vehicles stopped was just under 900.
Cetin said the team recently installed a LIDAR system to measure the actual heights of trucks traveling in the westbound direction. This system provides a rich dataset to better understand the height profiles of all trucks, especially those that trigger the over-height sensors. ODU and VDOT are hoping that the project will result in actionable recommendations to reduce over-height violations.
“This will ultimately improve the travel time reliability through the HRBT corridor for everyone,” Cetin said.
This story was published in partnership with WYDaily’s sister paper, Southside Daily.