Intelligent Transportation Systems in Work Zones: A Cross Cutting Study - Integrated Work Zone Systems for Improving Travel Conditions and Safety
Work zones cause congestion and result in more than 800 fatalities and 37,000 injuries in the U.S. every year. The increasing maintenance and rehabilitation of our aging infrastructure, combined with the growing travel and congestion on our roads, heightens the need for finding new ways to enhance mobility and safety in work zones. Forward-looking transportation agencies across the country are using ITS to make travel through and around the work zones safer and more efficient.
To better identify and document uses and benefits of ITS in work zones, the FHWA's ITS Joint Program Office conducted a cross-cutting study examining the application of ITS in work zones at sites in four states:
- Springfield, Illinois I-55
- Lansing, Michigan I-496
- Albuquerque, New Mexico I-40/I-25
- West Memphis, Arkansas I-40
All four sites employed ITS for monitoring and managing traffic and for providing traveler information. One site also used ITS for incident management. The purpose of the study was to share with other regions the experiences of early deployers of ITS in work zones.
The experiences of the four State DOTs examined in this study provide useful lessons for other agencies that are developing or deploying an ITS work zone system. Key strategies for ensuring project efficiency and productivity emphasize the importance of considering several critical factors early in the process.
- Address communications issues early in the ITS development and deployment processes. A reliable communications network is vital to ITS operations. Issues that may impact communications must be addressed early in the system development and deployment process. What may seem like a trivial issue at the outset may evolve into a more difficult problem when deploying or operating the system. Such issues include whether adequate cellular capacity is available and whether there are obstructions to signal transmission due to geography or terrain. The following experiences from specific sites add support to the lesson learned above.
- Michigan—It is sometimes necessary to apply for a licensed communications frequency to avoid problems with high-usage cellular telephone towers.
- Michigan—It is important to ensure that a thorough cellular coverage survey is conducted, as signal coverage can vary significantly over relatively short distances.
- Michigan—Obtaining a Federal Communications Commission license for highway advisory radio systems can be difficult because there are few available radio frequencies.
- Michigan—Radio frequency coverage can vary seasonally in heavily foliated areas.
- New Mexico—For wireless communications, it is important to ensure that the system Internet address has enough priority so that information gets through the network.
- Involve other stakeholder agencies early when developing a work zone management system. Other stakeholder agencies, such as those responsible for incident management, need to be involved early, in particular to determine how the system can work within each agency's existing procedures. Coordination with other agencies is a primary issue that agencies should consider when both developing and implementing an ITS work zone management system.
- Allow for sufficient start-up time when deploying an ITS application. Unanticipated issues may arise that will take time to address - for example, issues relating to operation of sensors or communications (wireless or wireline), or to license applications, system calibration, or software. Lessons learned related to specific sites include:
- Illinois—A significant amount of time is required for system calibration for queue length detection systems during initial implementation. One suggestion is to add 5 percent to the best estimate of the time required.
- Arkansas—Start-up time is needed for getting the system into place and fully operational. The construction project itself was delayed because it could not begin until the ITS system was operational and unanticipated delays were encountered in bringing the system on-line.
- Arkansas—Snags in system deployment may include traffic condition scenarios that were not anticipated in pre-programming of scenarios. The timing of some sensors had to be lengthened because the system was interpreting slow moving traffic as stopped vehicles.
- Consider terrain, access, and security issues when planning and implementing an ITS application.
- Michigan —Plan around rolling terrain to avoid difficulties in placing cameras where obstacles may be present. In addition, test the line-of-sight for cameras to be sure that the entire network is within the field of view.
- New Mexico—Allow for access to sensor stations because they may need to be reset manually, for example, after a power interruption.
- Arkansas—Vandalism can be a problem. Although securely locked, the control center trailer in Arkansas was broken into and the vandals ripped the system wires from their connections and destroyed the computer monitor. The system was down for several days while a replacement computer was shipped and then all the wiring was reconnected.
Transportation agencies across the country can benefit from the hard-earned experience of State DOTs that were early deployers of ITS in work zones. Their examples highlight a range of issues that should be addressed early in the development and deployment processes to increase the likelihood of efficient deployment and productive operations. Of particular importance are potential impacts on the communications network, the linchpin of any ITS work zone system. Involving a wide range of stakeholder agencies, such as those responsible for incident management, is also key to success. It is equally important to allow sufficient start-up time. Additionally, when locating equipment, consider terrain, access, and security issues. Applying these lessons learned could not only increase project efficiency and ITS system productivity, but lead to fewer crashes, shorter backups, and lower costs.