Work Zone Mobility and Safety Program


A photograph is provided showing a multilane highway at night with a portable directional sign set up next to the right lane.  STEP 6 - SYSTEM OPERATION, MAINTENANCE, AND EVALUATION

This step covers system operation and maintenance and includes sections on dealing with changing work zone conditions, using and sharing ITS information, maintaining adequate staffing, modifying the strategy and plan based on operational results, and leveraging public support, as depicted in Figure 21.

Figure 21. Sub-steps to be explored in Step 6. A text graphic shows a sequence of five items associated with Step 6. From left to right these are 6.1 Dealing with changing work zone conditions; 6.2 Using and sharing ITS information; 6.3 Maintaining adequate staffing; 6.4 Leveraging public support; and 6.5 Conducting system monitoring and evaluation. Source: Battelle
Figure 20. Sub-steps to be explored in Step 6.

6.1 Dealing with changing work zone conditions

One of the challenges for agencies operating ITS applications in work zones is maintaining system performance while adapting the system to changing work zone conditions and roadway geometries. The system may have to be repositioned or adjusted for various phases of construction that may involve different lane shifts or capacity reductions, for example. Other unexpected activities, such as parked construction vehicles, construction equipment storage, or law enforcement positioning in front of sensors, can cause issues that will need to be addressed in a timely manner.

Flexible and proven work zone ITS that can be dynamic or react in real-time is important for meeting real-time conditions. Not surprisingly, most agencies select highly portable systems built around proven technologies and wireless communications. Some systems have capabilities to communicate via cellular network or satellite depending on whether or not cellular communication is available in an area.

The provision of power for work zone ITS is another important consideration. Many work zones are located in rural areas that will not have convenient, direct access to power. However, if a wired power source is used, fewer options may be available for moving the system as changes in the work zone arise. Portable systems are typically powered through batteries with solar arrays for charging, or by having vendor staff continuously charging spare components and switching out charged components as needed. Power levels of batteries should be monitored periodically to ensure adequate charge, particularly if overcast conditions may have reduced solar charging.

Supporting a changing work zone requires significant coordination among the construction team, agency staff, and ITS operators. These challenges illustrate the importance of these considerations in system planning in Step 2, as well as developing close working relationships in the earliest stages of the planning process.

Clipboard IconKey Point: Sometimes conditions in the field may differ from what was expected during systems planning and design, and adjustments may be needed.
For example, queues may be longer or shorter than what was estimated before construction actually started. Personnel should monitor conditions in the field such that if queues regularly extend beyond the system signs (or detectors), the agency/contractor can consider adjusting the placement of the system components to make the most effective use of the system or adding additional devices to extend coverage.

6.2 Using and sharing ITS information

Information gathered from the work zone ITS might be used internally for traffic management purposes and to inform the use of other TMP strategies. Information about the work zone may provide insights about adjusting work zone hours, the lane closure schedule, the procedure to identify incidents, or fine tuning of alternate routes, diversion messages, or public outreach efforts.

Additionally, the benefits of the stakeholder relationship-building conducted in earlier stages of the project begin to appear. It is important to keep the stakeholders informed throughout the system operation step to ensure that cooperation and support for the effort continues. Discussion regarding the work zone ITS might be combined with related meetings such as those on maintenance of traffic, which are a venue for sharing ITS information, getting stakeholder input, and coordinating with other TMP strategies and the rest of the project. However, it is also important not to overload stakeholder partners with too much information.

Clipboard IconTip: Manage expectations.
It is important to assess and update expectations based on true experiences of the deployment in the work zone. The deployment may have greater or lesser impacts than originally anticipated, and it is important for stakeholders to understand why that is the case.

Work zone ITS differ in how they relay information to travelers via various media for pre-trip (i.e., website, email, text message) or en route (i.e., CMS or PCMS, HAR, in-vehicle navigational aids) decision making. In some systems, this information delivery is fully automated, whereas other systems require human confirmation of current traffic conditions and specific messages. Fully automated systems must be thoroughly and regularly tested to ensure that they are measuring conditions properly and that they are supplying the correct information for those measured conditions. Other ITS must be managed by operators, and require personnel to be available at all times while the system is running to confirm the conditions and to approve the message to be delivered to the travelers. Whichever option an agency chooses, the information delivered to travelers must be accurate; otherwise the public will lose confidence in the system.

Controls should be placed on message boards to prevent conflicting messages from being displayed along the same approach to the work zone area, to prevent messages from changing too often, and to prevent display of unhelpful information (e.g., work zone speed is 85 miles per hour). In addition, personnel from the implementing agency should have real-time access to archived system data in order to identify any issues and monitor system functionality. A website could easily provide password protected access to the data being used by the system to make decisions.

One of the most valuable products of ITS work zone applications is the development of real-time information that can be disseminated to a wide variety of users. ITS work zone systems collect data from several different types of roadside systems, process the data, and – with minimal human interaction – translate those data into valuable information for facility operators, emergency responders, and the traveling public. Provision of information can be a key in developing and maintaining stakeholder relationships, especially those involving agencies in other jurisdictions. Users of the information provided by the system may include state DOTs, the public and road users, nearby businesses and employers, media outlets, contractors, trucking companies, fleet operators, emergency services providers, motorist assistance patrols, neighboring jurisdictions, and third party traveler information providers.

A common method of information dissemination is through websites operated by state DOTs and other agencies. These websites also frequently include closed circuit television (CCTV) imagery from the ITS, which tend to be popular with travelers. Dissemination of this high quality information not only contributes to the operation of the system, but also builds credibility for the operating agency with the traveling public.

Clipboard IconTip: It is important to ensure that information delivered to the public is as accurate as possible.
If inaccurate information is provided, the public can quickly lose confidence, resulting in negative public relations.

Finally, it is important that data be archived or reported in a way that will be accessible and useful for evaluation of effectiveness. Data are required for project performance monitoring in real time, for post-project assessments of impacts that could be fed back to project designers to aid future project designs, and for agency process reviews, and assessment of work zone policies and procedures as required in federal regulations.

For example, many agencies specify maximum delay or queue length/duration thresholds that will be tolerated as part of their overall bid documents for a project. However, very few employ any type of actual monitoring efforts to aid field inspectors in determining if such threshold are being exceeded (and thus a need to shut down the activity causing the impacts), or to implement any type of penalties or damages for violating the thresholds. Archived work zone ITS data can provide an accurate, objective measure for such efforts.

As another example, work zone ITS data can be used during the project to help accelerate project activities and result in a quicker overall project with reduced impacts to the public. Many agencies have established hours that lane closures are restricted from occurring on high-volume roadways due to concerns over excessive delays and queues. However, oftentimes these restrictions are not tailored to the travel patterns that exist at a given project, but are agency-wide restrictions. During one recent arterial reconstruction project in Salt Lake City, work zone ITS was used to by the contractor to justify requests to UDOT to increase the allowable lane closure hours, still avoiding peak travel times and directions, that allowed the project to be completed faster than expected and not result in significant queues or delays for the traveling public.

As part of post-project assessments and overall process reviews, having more data available allows for a more thorough analysis and better conclusions. Work zone ITS, depending on the technology deployed, can assist an agency in assessing the frequency, duration, and magnitude of impacts that actually occurred. These can then be provided back to the work zone designers to compare against the results of their analyses. If their initial analyses were incorrect, it is often possible to determine the reasons for the incorrect outputs (i.e., error in estimating work zone capacity, diversion rates, etc.). This is an approach that the Michigan DOT has used regularly for its major work zones across the state. Consolidated across several projects, these work zone ITS data can also aid an agency in conducting its required bi-annual work process review. Basic performance measures can be determined for each project, such as45:

  • Maximum person throughput during peak hour;
  • Average per-vehicle delay during lane closure hours;
  • Percent of time when delays exceed the established maximum threshold;
  • Percent of travelers experiencing a traffic queue; and
  • Change in peak-period buffer time through a project.

Once project-specific measures are obtained and examined, it is also possible to aggregate across projects to develop an agency-wide perspective of performance. Examples of process-level measures for an agency could include:

  • Percent of projects where delays exceeded the maximum threshold;
  • Percent of projects experiencing increases in peak-period buffer indices by more than xx percent; and
  • Percent of projects experiencing traffic queues greater than some maximum threshold for some maximum duration.
Clipboard IconTip: Carefully consider how to set up automated information delivery and sharing with other agencies.
Particularly with an automated information delivery system, it is possible to deliver too much information for the agency and its partner agencies to process effectively. The frequency, usefulness, and volume of information delivered to managers and partners needs to be appropriate or it will likely be discarded or ignored. Many ITS applications can be set to automatically deliver texts or e-mails to the agency or partners such as the media and public safety agencies. If the thresholds for delivery of these messages are not carefully considered, a recipient may be inundated with information and unable to sort out what is useful.

6.3 Maintaining adequate staffing

If operations and maintenance are contracted out, it is the contractor’s responsibility to ensure that adequate, trained staff is available. However, if in-house staff are engaged, the agency must take steps to ensure that it has multiple staff members trained in system operations, maintenance, and troubleshooting. If these steps are not taken, the retirement or vacation of a key person may cripple the operation of the system or result in additional costs. It is in the agency’s best interest to select a set of project personnel who are expected to be available for the duration of the project.

6.4 Leveraging public support

A common thread that runs through comments made by agency personnel responsible for implementing ITS in work zones is the need to engage the public during the earliest stages of the project. Publicizing the advanced features of the work zone system and the type of information that will be available to the public is the first stage in developing public support for these systems. In this early stage, while it is important to share potential system benefits with the public, it is likewise important to temper expectations of the system, in case any of the benefits do not ultimately develop. Support from the public and elected officials combined with quantified benefits will help to ensure long-term funding availability for appropriate applications of ITS in future work zones.

6.5 Conducting system monitoring and evaluation

It is important to monitor the work zone ITS during its operation to ensure that it is working correctly and meeting the needs of its users, and that the vendor is meeting contract obligations. The data collected and analyzed over the course of the project can then be used as part of a more comprehensive evaluation at the conclusion of the project. In some instances, it may be necessary to modify the deployment to improve operations based on the results from system monitoring.

6.5.1 System monitoring

System monitoring and evaluation will be conducted based on the evaluation plan from Step 3. Data should be collected throughout the course of the ITS deployment according to the plan. Various data elements can be analyzed periodically throughout the course of the project to assess the system performance. It is expected that some data elements will be monitored and analyzed more frequently than others, e.g., on a daily, weekly, monthly, quarterly basis. Data should be used to determine whether system modifications are needed, and also assess the impacts of work zone operations on safety and mobility in the work zone.

Data alone will not be able to address all aspects of the ITS deployment that need to be monitored. Agency staff also need to make observations in the field, which can be logged as qualitative data. Together, the quantitative data and qualitative observations will help ensure that the system is working correctly or identify any changes that may need to be made. For example, system monitoring may show that it takes a long time to recover from the queues that develop before the system puts diversion messages on the PCMS. This may lead to changing the threshold for when diversion messages are displayed (e.g., from 3 mile queues to 2-mile queues). Depending on the location, scale, and duration of the project, it may be desirable to have cameras in the field for staff to monitor traffic conditions from an off-site location to validate sensor data and system-generated PCMS messages with observations. If issues are identified, they should be addressed immediately with the appropriate staff, i.e., contractor, vendor, or agency. It is important for the agency to then ensure that adjustments have corrected the problem and are made in a timely manner.

Clipboard IconTip: Questions to consider as you monitor the system during deployment.
  • Is the system working correctly? Are messages accurate based on conditions?
  • Is the vendor meeting the contract? Are issues being addressed promptly?
  • What are the data saying about work zone operations and safety and mobility in the work zone?
  • Does the system need to be adjusted (e.g., adjust thresholds, change the wording or timing of PCMS messages, reposition sensors, add sensors)?

System monitoring must be in line with the expectations of all groups that require feedback regarding the work zone ITS deployment. While system monitoring occurs for the entirety of the deployment, the detail of any ongoing monitoring and evaluation reports will likely vary at different intervals throughout the course of the project. Some DOTs maintain dashboards with various performance measures, which may require certain inputs from the deployment on a monthly basis, for example. Agency managers may request updates on a weekly basis, with more detailed reports on a quarterly basis. System monitoring must be scheduled in a way that meets these expectations.

Many work zones consist of multiple phases and many different tasks, which may or may not impact travelers. An evaluation of a work zone ITS deployment should be designed to evaluate effectiveness during those times and locations where impacts were expected to be most significant. The average delay per vehicle computed over an entire project may be very small, for example, if most of the work occurs off the roadway and only one or two days of work involves reductions in travel lanes. During those one or two days of lane closures, though, the average delay per vehicle will be much higher, and the effect of the work zone ITS on this delay is what will be of most interest to the agency. In other words, a work zone ITS evaluation must be carefully coordinated with field personnel to ensure that the evaluation is both appropriate and meaningful.

The work zone ITS evaluation should be done within the context of the TMP implementation, monitoring, and evaluation of the project. Data collected by the work zone ITS and the evaluation of the work zone ITS deployment may also inform an evaluation of other TMP strategies being used.

6.5.2 System modification

System monitoring may identify areas where modifications might be made to improve the performance of the work zone ITS. Discussions with stakeholders can also help to identify adjustments that are needed to system operation or information delivery mechanisms, content, and timing. For example, it may become apparent that additional sensor coverage is needed in a certain location because feedback from customers indicates that travel times being posted to PCMS are not as accurate as expected. In other instances, equipment (e.g., CMS) might be more effective if repositioned or by changing CMS messages for better user understanding.

Modification of a work zone ITS application will depend on both the scope of the system and the duration of the work zone. Adjustments to the deployment can sometimes be made without significant change orders or other efforts. Many of these adjustments do not require funding, but some may have additional costs that could pose a challenge for funding. Ideally, costly changes will be avoided through good system planning. In some cases, there may simply not be enough time to evaluate the system thoroughly, make changes, and then implement those changes in the midst of an ongoing construction project. However, some informal assessment of the system is always possible in order to verify the system is operating properly.

Traffic Cone IconExample: Making modifications to work zone ITS deployments – Illinois.
Agency and contractor staff should monitor work zone conditions, whether formally or informally, to identify ways to improve the system. A traffic management system was procured as part of the overall bid by the contractor for a work zone project on the I-70/I-57 interchange in Effingham, Illinois. Several PCMS were deployed as per the bid specification. Initially, PCMS displayed messages as called out in the contract, as shown on the left in Figure 22. However, as both IDOT and the contractor gained experience with the system and with how motorists responded to the various messages presented, changes to some PCMS messages were made, deviating from the contract. This included the display of specific speeds downstream as shown on the right in Figure 22. For example, the presentation of a given speed (as opposed to a generic “REDUCE SPEED AHEAD” message) was felt to elicit greater compliance by approaching motorists.

Other modifications may require additional funding. On a different project on the I-57/I-64 interchange in Mount Vernon, Illinois, queues occurred that were longer than originally expected. A change order was executed to add sensors and PDMS to the work zone traffic monitoring system that had already been deployed.

Figure 22. PCMS messages were modified from a generic message (left) as stated in the contract to a more specific message (right). Two photographs are provided. One shows a portable changeable message sign at the side of the road with text reading 'Reduce Speed Ahead.' The other shows a portable changeable message sign at the side of the road with text reading 'Speed Ahead 46 mph.' Source: FHWA
Figure 22. PCMS messages were modified from a generic message (left)
as stated in the contract to a more specific message (right).

6.5.3 Final evaluation

At the conclusion of the system deployment, a final evaluation should be conducted. A major objective of the final evaluation is to document lessons learned and benefits of the ITS deployment. This might include the collection of some final qualitative data from stakeholders, e.g., surveys or interviews. Analysis of all collected quantitative and qualitative data that has been collected over the course of the project should be conducted as described by the evaluation plan developed in substep 3.8. Examples of the results of two such evaluations are presented below.

The results, conclusions, and recommendations of the evaluation should be documented in a final report. These results can be used not only by the project partners for continual refinement of similar systems at other locations, but also by others wanting to implement similar systems in the future. The report might also be utilized to justify investments in work zone ITS deployments. ITS evaluation final reports can be entered in the ITS Benefits and Unit Cost Database,46 so that the evaluation results can be shared with other interested transportation professionals.

Key Takeaways
  • In this step, the work zone ITS becomes operational in the field with appropriate staff operating and monitoring the deployment, as necessary.
  • Flexibility is important. Agency or contractor staff need to be available to make adjustments, as necessary, due to changing work zone conditions and findings from ongoing system monitoring and evaluation.
  • A final evaluation should be conducted to include findings from any available data and detail the benefits and lessons learned from the system.

Traffic Cone IconExample: Effectiveness of a work zone ITS deployment – Effingham, Illinois.
A work zone ITS was deployed at the I-70/I-57 interchange in Effingham to mitigate the potential for end-of-queue crashes occurring due to traffic incidents or temporary lane closures within the project limits. An assessment of crashes occurring during the two construction seasons of the deployment suggests that the systems was useful and effective. From the first year to the second year of construction, the number of lane closure days increased, as did the amount of traffic exposure through the project. Even so, preliminary analysis by the Illinois DOT found that crashes decreased slightly, including end-of-queue crashes. Specifically, from 2010 (prior to system implementation) and 2011 (after system implementation) saw nearly a 14 percent decrease in queuing crashes, and an 11 percent reduction in injury crashes, despite a 52 percent increase in the number of days when temporary lane closures were implemented in the project. Although it is not certain whether the queuing frequencies and conditions between the two years were similar, the trends were very encouraging.

Traffic Cone IconExample: Effectiveness of work zone ITS deployment – Comparative Analysis.
An FHWA study of work zone ITS deployments revealed that 50 percent to 80 percent of surveyed drivers diverted at least sometimes due to messages provided on travel time, delay, or alternate routes. The same study noted 56 percent to 60 percent reductions in queue lengths were possible. Finally, it was found that speed monitoring displays could reduce speeds by 4-6 mph, with one study finding a 20 percent to 40 percent reduction in vehicles traveling at least 10 mph over the speed limit with these devices present. (see

45Ullman, G.L. et al. Guidance on Data Needs, Availability, and Opportunities for Work Zone Performance Measurement. Report FHWA-HOP-13-011. FHWA, U.S. Department of Transportation, Washington, DC, March 2013.
46The database is available online at:; the website has instructions on how to contribute.

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