Address critical issues early in the ITS work zone management system development and deployment processes, and allow sufficient start-up time.
The experiences of four state DOTs using ITS in work zones.
Statewide,Illinois,United States; Statewide,Arkansas,United States; Statewide,Michigan,United States; Statewide,New Mexico,United States
- 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.
Author: Scriba, Tracy
Published By: Federal Highway Administration, U.S. DOT
Prepared by SAIC for the U.S. DOT
Source Date: November 2002
EDL Number: 13600
Other Reference Number: Report No. FHWA-OP-02-025URL: http://ntl.bts.gov/lib//jpodocs/repts_te//13600.html
Volpe National Transportation Systems Center
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