Road Management & Engineering Journal
Road Management & Engineering Journal
Copyright © 1998 by TranSafety, Inc.
May 1, 1998
TranSafety, Inc.
(U.S. and Canada)
(360) 683-6276
Fax: (360) 335-6402

Chicago Study Focuses on Improving Traffic Management at Incidents on Urban Arterial Roadways

When an incident--such as a crash or hazardous spill--occurs on a roadway, the first concern of professional emergency responders is to protect life and property. However, in the aftermath of such an incident, it is also important to maintain safe and efficient traffic operations, thus avoiding delays and the costs associated with them. Traffic congestion and delays can lead to other incidents, including secondary crashes. Efficient roadway management "plays a key role" in Intelligent Transportation Systems (ITS) and "should be considered an important part of ITS planning."

Efforts at incident management have focused primarily on limited-access highways; however, urban arterial roadways present different and often more complex management concerns. The Arterial Incident Management Study (AIMS) looked at the status of incident management on several arterial roadways. Conducted for the Illinois Department of Transportation, the study focused on the apparent low-priority status of traffic operations for professionals who respond to incidents. This neglect of traffic operations can often worsen congestion.

Richard A. Raub and Joseph L. Schofer reported the study's findings in "Managing Incidents on Urban Arterial Roadways," published in Transportation Research Record 1603. The study "found that a broad and integrated response to incidents that focuses on the victims, vehicles, material and personal hazards, and traffic operations is important to successful incident management." With that goal in mind, the study offered numerous recommendations to professionals involved in incident management.


Incident management involves three objectives: to "protect life and property; minimize capacity loss (flow disruption) duration, intensity, and geographic extent; and gather required investigative information." The congestion, cost, and secondary-crash potential that result from incidents would suggest that "minimizing capacity loss should be assigned a high priority along with protecting life and property." Improved incident management seeks to reduce the time of the "response phase," which starts when the incident happens and ends when all debris is cleared and normal traffic resumes.

Previous research has identified a number of key factors that compromise incident management. These factors include (1) poor communication, coordination, planning and evaluation; (2) too little information, concern, and knowledge of incidents and their impact on traffic; and (3) too many responders who take too long to process and clear an incident from the roadway. A delayed response phase can be the result of any or all of these factors.


The study included a literature review, an analysis of police records, field observations, discussions about specific incidents with the responding personnel, and incident simulations with experts involved in incident management. The study defined roadway incidents "as any unexpected events that have the potential to restrict the flow of traffic along an arterial roadway, that are temporary and localized in nature, and for which some form of intervention usually is necessary to complete and restore traffic flow." The study took place in seven suburbs in the Chicago metropolitan area for twenty- eight days in January and February 1995. Researchers collected data from 6:00 a.m. to 9:59 p.m.--attempting to gather a representative sample of incidents and learn at what times they would most affect traffic. Table 1 illustrates the incident types examined and shows that crashes had the longest response phase (an average of fifty- seven minutes overall, and seventy-one minutes for those involving injury).

Analysis of Incidents Occurring Along Arterial Roadways, January-February 1995

Class of Incident
Time in minutes











Recommendations focused on the key problem issues of incident management and emphasized "effective and timely communication" among all those associated with an incident. For example, dispatchers and other "call-takers" need accurate and complete information to dispatch appropriate emergency responders. Police officers typically report incidents, but "civilians" also report them; however, call-takers may view civilian reports as "suspect" because of their lack of emergency-response knowledge. Educating the public to report incidents could be accomplished through a number of avenues, including vehicle registration inserts, insurance premium notices, driver education courses, and training for workers whose jobs put them on the road, such as bus and taxi drivers. Civilians can also be specially trained as crash investigators, which frees "official personnel to manage the scene."

A police officer is usually the first to respond to an incident and frequently manages most activities at the scene. The effectiveness of that management depends on the skills of the officer, and often coordination efforts are not effective when more than one officer or agency is involved. A more effective approach can be making the responding police officer the automatic commander and coordinator of the incident scene--until officially relieved or replaced by other response personnel (such as the fire department). First responders, regardless of professional agency, should (1) park their vehicle(s) to protect the scene yet maintain traffic flow, (2) perform a triage of the scene to determine priorities, and (3) request appropriate tow services. Telecommunicators (dispatchers) "are in an excellent position to provide more advanced scene coordination," and "should be trained to function more actively as off-scene coordinators."

All first-reponse and ongoing efforts should be governed by "safe and efficient traffic management." When necessary, on-scene personnel "should provide traffic direction" and "traffic rerouting." All emergency response vehicles "should carry or have rapid access" to items (e.g., cones and signs) needed. Responders should arrange detours when the road is closed for more than thirty minutes or when use of opposing traffic lanes is not feasible. Detour routes should be planned in advance in cooperation with the public works department, and public works should be an active partner in on-scene incident management. Police and fire personnel should be trained to "minimize lane blockage," and the scene commander should be responsible for minimizing "the impact of the emergency reponse activity itself." The need for communication among various response agencies requires a common radio frequency and access to multichannel radios for those in the field.

Timely removal of vehicles and debris from the roadway is an important factor in maintaining safe traffic operations. One way to facilitate this is through legislation "requiring that vehicles involved in minor collisions and drivable be removed from the roadway before police are contacted." This legislation, already a reality in many states, should be supported by police and insurance agencies. In addition, the authors recommended that "during peak hours, motorists should not have a right of tow refusal."

Communication with approaching motorists can do much to alleviate congestion and other problems at the scene. As such, "policies and criteria should be established to guide telecommunicators and off-scene managers in disseminating information about large-scale, long-duration incidents." Estimating the incident's duration is important, and "broadcast information for motorists should include specific guidance for revised routes."

Planning for different types of incidents can speed up on-scene management and reduce traffic disruptions. Therefore, "procedures should be in place that define for call-takers, public safety telecommunicators, responding officers, supervisors, and management what steps each should take to reduce the effects of the incident." Planning and coordination are needed not only among the agencies within a jurisdiction but also among various jurisdictions--in order to define authority and determine resources. Planning also requires carefully evaluating current policies and procedures.

Finally, this study showed that "debriefings among responders to specific incidents can provide a good basis for evaluation, problem solving, and cooperative relationships," and "such debriefings should be regular activities of incident responders." The authors recommended that "police and fire supervisors should observe and evaluate the response to some minimum number of events each year to assess performance of their personnel in managing incident scenes."


Incident management calls for the skills of many trained personnel and resources from a variety of agencies, all involved in "a coordinated effort designed to expedite clearing the scene, protecting those involved, and reducing the effect on traffic." Such an effort requires a "multifaceted approach," emphasizing education, communication, and planning. The result is a more effective and efficient system of management that reduces the significant direct and indirect costs associated with roadway incidents.

Copyright © 1998 by TranSafety, Inc.

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