In 2002 the Maryland State CHART highway incident management system facilitated a 28.6 percent reduction on the average incident duration leading to an estimated 377 fewer secondary incidents.

Maryland Incident Management System

November 2003
Statewide; Maryland; United States

Summary Information

The CHART (Coordinated Highways Action Response Team) highway incident management program is a collaborative effort between the Maryland DOT State Highway Administration (SHA), Maryland Transportation Authority (MTA), Maryland State Police (MSP), Federal Highway Administration (FHWA), the University of Maryland, and several local governments. Initiated in the mid-1980s as the "Reach the Beach" program, the program was designed to support safe travel to and from Maryland's eastern shore. By the year 2000, CHART operations became part of a regional advanced traffic management system for the Baltimore - Washington region. The regional system included a statewide operations center (SOC) and three satellite traffic operations centers (TOC) that were deployed to improve real-time operations on commuter routes. Recently, in cooperation with federal, state, and local agencies, CHART has expanded into a statewide system. At the time of this report, CHART consisted of the following operational components: traffic monitoring, incident response, traffic management, and traveler information (i.e., live traffic cameras, real-time traffic maps, weather, and local traveler information).

The overall objective of the CHART 2002 study was to assess the effectiveness of CHART/SHA operations. It was noted that an ideal comprehensive evaluation of incident duration would consider detection time, response time, and traffic condition recovery time; however, at the time of this study, the data on detection time and complete response time were limited. The impact analysis in this report was based primarily on incident data collected from MSHA patrols and Maryland State Police (MSP) reports.

The results below highlight the findings of an analysis of incidents with and without response by CHART personnel. The authors note that the available "without" data were limited, given that CHART was responding to most incidents within its coverage area by 2002.


In 2002, CHART responded to a total of 13,752 lane-blocking incidents and provided assistance to 19,062 drivers of disabled vehicles that may otherwise have caused incidents or rubbernecking delays. Taking into account all types of incidents, the average incident duration with and without management by CHART response units was estimated to be 28 minutes and 39 minutes, respectively. This represented a 28.6 percent reduction in average incident duration. The performance improvement of CHART from the year 1999 to 2002 is summarized below:

Average Incident Duration
with CHART (minutes)

Average Incident Duration
without CHART (minutes)*













* The authors noted that the reduction in duration for incidents without CHART response may be due to increasing attention to the value of reducing incident duration by all responding agencies.

In 2002, there were 941 secondary incidents in the CHART coverage area. Based on the data collected, the study found that the cumulative number of secondary incidents increased with increased duration of primary incidents. In this study secondary incidents were defined as:
  • Incidents within two hours from the onset of a primary incident and also within two miles of the primary incident
  • Incidents in the opposite direction that are within a half-hour from the onset of a primary incident and lie within a half-mile either downstream or upstream of the primary incident location.
Given the finding that CHART contributed to a 28.6 percent reduction in the average incident duration, and assuming that the correlation between increased primary incident duration and increased secondary incidents was linear in nature, this study estimated that CHART operations resulted in 377 fewer secondary incidents in 2002.

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Performance Evaluation of CHART (Coordinated Highways Action Response Team) Year 2002 (Final Report)

Author: Chang, Gang-Len, et al.

Published By: Maryland State Highway Administration

Prepared by the University of Maryland for the State Highway Administration of Maryland

Source Date: November 2003



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Goal Areas


Typical Deployment Locations



freeway service patrol, courtesy patrols, highway helpers, freeway service patrols

Benefit ID: 2007-00425