The Mobility Monitoring Program (http://mobility.tamu.edu/mmp/) provides valuable insights with respect to using archived traffic detector data for monitoring highway performance (e.g., traffic congestion and travel reliability). The Mobility Monitoring Program was initiated in 2000 using archived freeway detector data from 10 cities. By 2004, the Program had grown to include nearly 30 cities with about 3,000 miles of freeway. Over the first four years of the Program, the project team gained valuable experience in the course of gathering archived data from State and local agencies. These experiences were captured in the report "Lessons Learned: Monitoring Highway Congestion and Reliability Using Archived Traffic Detector Data." The lessons documented in this report focus on three general areas: analytical methods, data quality, and institutional issues. They are useful to the Federal Highway Administration (FHWA) as it expands the national congestion monitoring program and to State and local agencies as they develop their congestion monitoring capabilities.
The FHWA and U.S. Department of Transportation (DOT) are responsible for reporting their performance in meeting agency goals, one of which is related to mobility and highway congestion. Data collected for national performance reporting are contributed by State and local agencies. Thus, FHWA relies on State and local agencies to provide data in a standard format (such as in the Highway Performance Monitoring System). Alternative data sources that are being explored include archived traffic detector data and traveler information data, which are not typically provided in a standard format by State or local agencies. The end result, standard format or not, is that in many cases the gathered data are not sufficient to explain and interpret various trends in system performance. Local knowledge from State or local agency personnel is often required to interpret trends or better understand changes or relationships in system performance measures.
- Capture local knowledge for interpreting system performance at a national level. State and local agencies are likely to be more familiar with highways in their jurisdiction and significant activities or events that affect system performance. State and local agencies may monitor performance using methods or techniques that conform with or differ from national congestion monitoring measures. Because of their experience with local issues, State and local agency staff may also be able to provide "reality checks" for data collected in national congestion monitoring. At best, this capture of local knowledge is currently an informal process that involves sporadic communication with State and local agencies. There appears to be a need to formalize a process that solicits the knowledge and experience (as well as "event" databases) of State and local agencies in national congestion monitoring.
- Texas Transportation Institute (TTI) researchers have been gathering this local knowledge for many years through several of their national congestion studies. In the media-friendly Urban Mobility Study, which reported congestion statistics for 75 cities using Highway Performance Monitoring System (HPMS) data, TTI researchers contacted State DOTs and metropolitan planning organizations to better understand or interpret reported trends in road mileage and travel statistics. These contacts were essential for smoothing year-to-year fluctuations caused by reporting differences or inconsistencies.
- Promote the local use of archived data for performance monitoring because it will benefit national performance monitoring efforts. In the Mobility Monitoring Program, which reports congestion statistics for numerous cities using archived data, TTI researchers informally solicit feedback on city-specific reports that contain route-by-route congestion and reliability statistics. In most cases, State or local agencies have confirmed the overall trends reported. However, some State or local agencies occasionally dispute the credibility of the archived traffic data as compared to their local congestion studies or experience. Many times these agencies are not currently using archived data for local performance monitoring. If they were, the archived data could support their positions and help improve both data quality and data utility for national purposes.
When State and local agencies capture their local highway knowledge and report this information to federal agencies, federal agencies can better explain and interpret various transportation trends in system performance. State and local agencies that are not currently using archived data for local performance monitoring should be encouraged to do so in order to provide federal agencies with additional useful information.
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