An Active Traffic Management System (ATM) on I-66 in Northern Virginia reduced total (all severity), multiple-vehicle (all severity), and rear-end (all severity) crashes, 6 percent, 10 percent, and 11 percent, respectively.
The Phase II Evaluation Report detailed the ATM strategies implemented and the corresponding safety evaluation.
Made Public Date
12/26/2018

833

Fairfax County
Virginia
United States
Identifier
2018-01336
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Evaluation of the Impact of the I-66 Active Traffic Management System: Phase II

Summary Information

This Phase II project evaluated the performance of an Active Traffic Management System (ATM) system installed on I-66 in Northern Virginia. An operational analysis was conducted from October 2015 through November 2017 and a safety analysis was conducted from October 2015 through December 2016.

In early 2013, construction began on a Virginia Department of Transportation (VDOT) project to install an ATM system on I-66 from US 29 in Centreville to the Capital Beltway. Construction was completed in September 2015 and spanned approximately 12.4 miles. The primary ATM strategies implemented on I-66 included:

  • Variable Speed Limits (VSL): On I-66, the normal posted speed limit is 55 mi/h, but the VSL system can post speeds between 35 mi/h and 50 mi/h above each lane depending on traffic conditions.
  • Hard Shoulder Running (HSR): The I-66 HSR system dynamically opened or closed the shoulder lanes depending on roadway conditions.
  • Lane Use Control Signals (LUCS): For incident and work zone management, overhead gantries were deployed with LUCS to alert drivers to lane blockages.

METHODOLOGY

A segment-level analysis was performed to determine the segments that had benefitted the most from the implementation of the ATM system.

FINDINGS

The safety evaluation showed 6 percent, 10 percent, and 11 percent reductions in total (all severity), multiple-vehicle (all severity), and rear-end (all severity) crashes, respectively. Further analysis again demonstrated segments with HSR saw the largest safety improvements.

The operational analysis showed that travel time improved significantly during off-peak hours after the ATM system was activated but that travel time during peak periods in the peak direction of travel generally did not improve. Most of these improvements occurred on HSR segments.

Evaluation of the Impact of the I-66 Active Traffic Management System: Phase II

Evaluation of the Impact of the I-66 Active Traffic Management System: Phase II
Publication Sort Date
10/01/2018
Author
Dutta, N., et al.
Publisher
Virginia DOT
Other Reference Number
VTRC 19-R7

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