ITS Benefits >> Active Traffic Management system installed along I-66 reduces travel times by up to 11 percent and reduces vehicle delay by up to 68 percent

In September 2015, the Virginia Department of Transportation (VDOT) activated an active traffic management (ATM) system on I-66 through Arlington, Fairfax and Prince William counties from the Washington, D.C. line to Route 29 in Gainesville. The system includes new overhead sign gantries, shoulder and lane control signs, speed displays, incident and queue detection, and increased traffic camera coverage. A total of 21 overhead gantries were installed in each direction between the Beltway and Route 29 in Centreville and were spaced .6 miles apart.

Methodology
State researchers looked at travel times between the Centreville exit and the Capital Beltway (approximately 12.5 miles) to determine the impact of the new signage and changes to the use of the shoulder lanes. Data were analyzed for October 2014 to February 2015 (Before-ATM) and from October 2015 to February 2016 (After-ATM).

Findings

Hard Should Running Utilization in Hours (Average hours of operations/ day per Gantry)

Direction - Average Day Before ATM After ATM
Eastbound - Weekday 5.5 8
Eastbound - Weekend N/A 2.4
Westbound - Weekday 6 6
Westbound - Weekend N/A 2

Avg EB Weekday Travel Times

Time Period Oct 2014 - Feb 2015 Oct 2015 - Feb 2016 Change
AM Peak
(5:30 AM - 11 AM)
17.0 min 18.2 min +1.2 (+7%)
Midday
(11 AM - 2 PM)
13.3 min 13.2 min -0.1 (-1%)
PM Peak
(2 PM - 8 PM)
14.7 min 13.7 min -1.0 (-6%)

Avg EB Weekend Travel Times

Time Period Oct 2014 - Feb 2015 Oct 2015 - Feb 2016 Change
Daytime Peak
(10 AM - 8 PM)
14.5 min 13.1 min -1.4 (-10%)

Avg WB Weekday Travel Times

Time Period Oct 2014 - Feb 2015 Oct 2015 - Feb 2016 Change
AM Peak
(5:30 AM - 11 AM)
12.6 min 12.3 min -0.3 (-2%)
Midday
(11 AM - 2 PM)
13.3 min 12.7 min -0.6 (-5%)
PM Peak
(2 PM - 8 PM)
21.7 min 22.5 min +0.8 (+4%)

Avg WB Weekend Travel Times

Time Period Oct 2014 - Feb 2015 Oct 2015 - Feb 2016 Change
Daytime Peak
(10 AM - 8 PM)
13.7 min 12.2 min -1.5 (-11%)

Total Traveler Delay (veh-hour)

Direction Average Day Before ATM After ATM Change
Eastbound Weekday 2968.5 3353.4 +13.0 %
Eastbound Weekend 1682.5 704.7 -58.1 %
Westbound Weekday 5121.6 5583.3 +9.0 %
Westbound Weekend 1292.5 416.8 -67.8 %

Conclusions

  • The ATM system had minimal effect on travel times during weekday peak periods, since shoulders were already in use before installation.
  • Small benefits were observed in the off peak direction and during midday periods during the week.
  • Flow improved substantially during the weekends. Both mean travel time and travel time reliability improved by a statistically significant amount.
  • Most operational improvements appear to be attributable to shoulder lane usage.
  • Preliminary safety data is promising, but more data is needed.



Posted: 2017-02-17 14:14:41


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