The Hampton Roads Transportation Planning Organization (HRTPO) monitors regional roadway congestion through the Congestion Management Process (CMP). Historically, HRTPO staff has estimated peak hour congestion levels on each roadway segment based on traffic volumes collected over a short time period and roadway characteristics.
In recent years, new technologies have been created that collect travel time and speed data on a continuous basis. One source of such data, INRIX, provides real-time and historical travel time and speed data on an extensive roadway network. For 1,300 miles of roadway throughout Hampton Roads, INRIX provides averaged travel time and speed data in 15-minute intervals. HRTPO staff used this 2010 archived data to determine travel times and speeds, congestion levels and durations, and delays on regional roadways.
For each roadway segment, Speed Reduction Factors were calculated to determine the slowest roadways in the region. Speed Reduction Factors are defined by the Texas Transportation Institute as the ratio of the actual segment travel speeds divided by the segment free flow travel speeds. A total of 29 roadway segments throughout the region have a minimum Speed Reduction Factor of 0.40 or lower during the AM Peak Period (defined in this study as occurring between 6 am and 9 am), and 54 segments meet this threshold during the PM Peak Period (defined as occurring between 3 pm and 7 pm). Many of these segments, as shown in the table, include high profile facilities throughout the region such as the approaches to the Downtown Tunnel, Midtown Tunnel, Hampton Roads Bridge-Tunnel, High Rise Bridge, and Gilmerton Bridge.
This INRIX data was also used by HRTPO staff to determine the duration of congestion, which HRTPO staff had not been able to do with previous congestion analysis methods. A total of 34 roadway segments throughout Hampton Roads are severely congested for at least 9 of the 12 15-minute intervals during the AM Peak Period, and 50 roadway segments are severely congested for at least 13 of the 16 15-minute intervals during the PM Peak Period. Similar to the lowest Speed Reduction Factors, many of the roadway segments with the longest congestion durations include high profile facilities throughout the region such as the Downtown Tunnel, Midtown Tunnel, Hampton Roads Bridge-Tunnel, High Rise Bridge, and Gilmerton Bridge.
As part of this study, a number of high profile locations throughout Hampton Roads were analyzed in further detail. This includes the length, duration, and level of congestion during the AM and PM Peak Periods at each location, and the total delay during each peak period. Among the ten high profile locations studied in this report, the Downtown Tunnel has the highest peak period delays in both the AM and PM Peak Periods. The Midtown Tunnel has the second highest delay during the AM Peak Period, while the Hampton Roads Bridge-Tunnel has the second highest delay during the PM Peak Period.
The Hampton Roads Regional Travel Time/Speed Study is available here.