Office of Operations
21st Century Operations Using 21st Century Technologies

TRAFFIC INCIDENT MANAGEMENT IN CONSTRUCTION AND MAINTENANCE WORK ZONES

6.0 ENHANCING FUTURE WORK ZONE TRAFFIC INCIDENT MANAGEMENT ACTIVITIES

Work zones can be a catalyst for changing existing incident management and policies in an area. In some cases, new strategies and techniques that are implemented as part of the transportation management plan (TMP) for the construction or maintenance project will remain in place after the construction is gone. In other cases, the lessons learned associated with implementing some of these strategies in one work zone can be valuable information to work zone planners and incident responders in the next construction project. This chapter focuses on actions that work zone planners, traffic operators, and incident responders can take during the execution of a particular work zone project that can provide insight into enhancement or improvements to incident management activities in the future.

Performance Monitoring and Evaluation

Monitoring and measuring the effectiveness of the incident management strategies in work zones is an essential step in identifying improvements and enhancements for future traffic incident management activities. Table 10 shows a series of performance measures that have been recommended for measuring the impact of incidents and work zones on freeway operations.18

The National Transportation Operations Coalition (NTOC) has proposed using the measures shown in Table 11 as core measures for evaluating the impacts of incidents on traffic operations.19 Similar performance measures can be used to measure the effectiveness of various work zone related traffic incident management strategies.

Other measures that are used to gauge the effectiveness of incident management programs are: 20, 21

  • Roadway Clearance Time: the time between the first recordable awareness (detection/notification/awareness) of an incident by a responsible agency and the first confirmation that all lanes are available for traffic flow.
  • Incident Clearance Time: the time between the first recordable awareness and the time at which the last responder has left the scene.
  • The number and overall percentage of responses by type.
  • The number of responses and overall average clearance time.
  • The number of responses and overall average clearance time for fatality collisions.
  • The number of responses and overall average clearance time for non-collision incidents.
  • The number of responses and overall average clearance time for service actions taken.
  • The number (or percent) of incidents that exceed a specified duration (e.g., 2 hours).
  • The average clearance time by month.
  • The average clearance time by quarter.
  • The number and percentage of blocking incidents by quarter.
  • The number and percentage of injury incidents by quarter.
  • The number and percentage of non-injury incidents by quarter.
  • The number and percentage of fatality incidents by quarter.

Table 10. Recommended Core Measures for Capturing Impacts of Incidents and Work Zones on Freeway Performance

Performance Metric Definition Units Geographic Scale Time Scale
Incident Characteristics (Activity-Based)
No. of Incidents by Type and Extent of Blockage Self-Explanatory Type: 1)  crash, 2) vehicle breakdown, 3) spill, 4) other.Blockage: actual number of lanes blocked; separate code for shoulder blockage Section and area wide Morning/Evening peak periods, daily
Incident Duration The time elapsed from the notification of an incident to when the last responder has left the incident scene Minutes (median) Section and area wide Morning/Evening peak periods, daily
Blockage Duration The time elapsed from the notification of an incident to when all evidence of the incident (including responders’ vehicles) have been removed from the travel lanes Minutes (Median) Section and area wide Morning/Evening peak periods, daily
Lane-Hours Loss Due to Incidents The number of whole or partial freeway lanes blocked by the incident and its responders, multiplied by the number of hours the lanes are blocked Lane-hours Section and area wide Morning/Evening peak periods, daily
Work Zones (Activity-Based)
No. of Work Zones by Type of Activity The underlying reason why the work zone was initiated: 1) resurfacing only, 2) Resurfacing, Restoration, and Rehabilitation (RRR) projects, 3) lane addition w/o interchanges, 4) lane additions with interchanges, 5) minor cross-section, 6) grade flattening, 7) curve flattening, 8) bridge deck, 9) bridge superstructure, 10) bridge replacement, 11)sign-related Number  Section and area wide Daily
Lane-Hours Lost Due to Work Zones The number of whole or partial freeway lanes blocked by the work zone, multiplied by the number of hours the lanes are blocked Lane-Hours Section and area wide Morning/Evening peak periods, daily
Average Work Zone Duration by Type of Activity The elapsed time that work zone activities are in effect Hours Section and area wide Daily
Lane-Miles Lost Due to Work Zones The number of whole or partial freeway lanes blocked by work zone, multiplied by the length of the work zone Lane-miles Section and area wide Morning/Evening peak periods, daily

Adapted from Guide to Effective Freeway Performance Measurement18

Table 11. NTOC Performance Metrics for Measuring Impacts of Incidents19

Measure Definition Sample Units of Measurements
Incident Duration The time elapsed from the notification of an incident until all evidence of the incident has been removed from the incident scene. Median minutes per incident
Non-recurring Delay Vehicle delay in excess of the recurring delay for the current time-of-day, day-of-week, and day-type. Vehicle-hours
Travel Time Reliability (Buffer Time) The additional time that must be added to a trip to ensure that travelers making the trip will arrive at their destination at or before the intended time 95 percent of the time. Minutes. This measure may also be expressed as a percent to total trip time or as an index.

It should be noted that if a performance-based, incentive/disincentive-based contract is used to provide a guaranteed incident response time, then a system needs to be put into place to measure whether or not a contractor has fulfilled the contract obligations. As part of the contract documents, work zone planners need to develop a performance assessment plan which describes how the contractor’s performance will be evaluated and assessed. Several methodologies can be used for assessing a contractor’s performance related to the specific incident management function, including the following:

  • Random sampling,
  • Periodic sampling,
  • Trend analysis,
  • Customer feedback, and
  • Third-party audits.

Good performance monitoring and evaluation often requires developing additional reporting capabilities and resources not commonly available. Work zone planners and incident responders should be careful not to use performance measures that exceed the existing data collection and reporting systems’ capabilities to collect the data needed to produce the performance measures.

Post-Incident Debriefings

Many locations routinely conduct post-incident debriefings after major incidents. The purpose of these debriefings is to identify deficiencies, lesson learned, and areas for improvement to apply to future incidents. The debriefings can also serve as a forum for resolving conflicts and inefficiencies between responders. Many agencies have found that these debriefings help to maintain and strengthen the lines of communications between incident responders. Incident debriefings can also assist agencies with their NIMS/ICS preparedness activities.

The process for conducting a post-incident debriefing includes the following steps:

  • Recreate the incident chronology for the participants,
  • Collect input from each agency on the aspects of the response that worked well as well as critiques of the aspects that worked poorly,
  • Collect suggestions from each agency for improving the response for future events,
  • Discuss the suggestions for improvement and develop consensus as to the corrective actions to be taken in future events,
  • Document the results of the debriefing and update the incident response / action plan

Typically, an incident debriefing includes all the major stakeholders that responded to the incident. Ideally, both field and supervisory personnel should be involved in the debriefing. Construction personnel and work zone planners should also be included as part of the debriefing to offer insight into how the actions could impact phasing or scheduling of work activities and modifications that may be required to the TMP. These debriefings should occur as soon as practical following the incident, while the actions and issues are still fresh on the responders’ minds. Consideration should be given to using a facilitator to keep the debriefing frank, but non-confrontational. Action items, if needed, should also be clearly and concisely summarized and incorporated into future responses.

Documentation, Evaluation, and Lessons Learned

At the conclusion of the work zone activities, work zone planners, construction personnel, and incident responders should assess the overall effectiveness of the incident management strategies and techniques employed as part of the project TMP. The feedback will be a valuable asset in planning future work zone activities. Specifically, construction personnel and incident responders should be asked to evaluate the strategies used against the traffic incident management objectives defined during the work zone planning processes. Construction personnel and incident responders should specifically assess the following:

  • Did the strategies help reduce the time required to detect the presence of incidents in the work zone?
  • How did the strategies help expedite the clearance of incidents in the work zone?
  • How did the strategies help facilitate or improve incident responses in the work zone area?
  • Did the strategies deployed reduce the frequency and severity of crashes and secondary crashes in the work zone?
  • Did the strategies reduce the number of public safety personnel needed to respond to the incidents?
  • How did the strategies impact incident responder safety, cooperation, and collaboration within the work zone?
  • How might customer satisfaction be improved in future work zone traffic incident management efforts?

Steps should also be taken to document the effectiveness of the strategies, wherever possible, using the performance measures previously discussed.