About the research
The Iowa Department of Transportation (DOT) leverages a network of cameras, sensors, and weather probes to identify congestion and threats to traveler safety. The Iowa DOT has also partnered with INRIX and Waze to collect baseline probe data for input into real-time highway operations.
Iowa DOT traffic operations staff rely on all of these data sources to monitor and analyze traffic in the state’s traffic management center (TMC). The TMC dispatches personnel to address incidents and disseminate information through Iowa’s 511 portal and via dynamic message signs. After incident occurrence, the Iowa DOT’s strong partnerships and rich data help the Iowa DOT proactively prepare for future incidents. This includes system management strategies or identification of future highway system needs.
The Iowa DOT has made recent strides in data analysis, turning raw data into actionable information. The Iowa DOT has begun preparing two performance reports: Iowa Mobility Report, the monthly TMC Performance Measures Report, and Winter Storm Event Operations Report. Through visualization and trend analysis, the reports portray detailed information on impacts to system efficiency due to weather or crashes. The reports also highlight the roles of various systems and strategies, promoting the incremental improvement of all systems and strategies for future months or future major weather events to achieve more consistent, predictable highway travel times.
The Iowa DOT has embraced a transportation systems management and operations (TSMO) culture of “To get you there safely and reliably by proactively managing the transportation system.” Hence, the Iowa DOT has developed a TSMO Plan that includes strategic, programmatic, and tactical guidance to enhance the Iowa DOT’s abilities to monitor, analyze and improve the state’s transportation system. The TSMO Plan focuses on optimizing the Iowa DOT’s existing systems and promotes efficient future expansion of systems.
The Iowa DOT also leveraged the SHRP2 L06 product to conduct a self assessment of the department’s readiness to make TSMO a core function. That self assessment highlighted notable weakness in performance measurement, and the Iowa DOT’s TSMO Plan now includes guidance on performance measurement for travel time reliability, travel efficiency, and traveler safety. The Iowa DOT intends to rectify the deficiency with the SHRP2 Reliability Data and Analysis Tools.
Implementation of the SHRP2 Reliability Data and Analysis Tools are consistent with the department’s TSMO strategies to improve system reliability and increase system resiliency. Furthermore, the tools will facilitate a synergy among system operations, planning, and design staff by jointly using the reliability data and analysis tools to promote a more reliable transportation system.
The Iowa DOT has partnered with the Iowa State University Center for Transportation Research and Education (CTRE) to start development of a high-performance, computing-driven approach for implementation of the L02 tool. CTRE’s REaltime AnalytiCs of TranspORtation (REACTOR) data laboratory will serve as a test bed to develop an online tool (using the SHRP2 guidelines) to assess, report, and eventually predict travel-time reliability across the Iowa transportation network.
The tool will provide the ability for clients to analyze the impacts of work zones, weather, and incidents on travel time via the cumulative distribution function (CDF) for the facility. Factors such as fluctuation of demand, special events, and inadequate base capacity will be assessed on a case-by-case basis. The freeway system will be the focus of REACTOR, but the tool could be expanded to the arterial system as higher quality data becomes more readily available.
The tool will also develop models to classify an existing day’s pattern to a specific regime and also enable predictions of travel-time reliability impacts of the above mentioned factors. Curves will be constructed for segments across the state’s freeway system and anomalies will be automatically coded and classified.
Our plan to test the reliability analysis tools L07 and L08 includes three facets. First, we will benchmark/validate the products to historical conditions based on our work with the L02 product. Second, we will test alternative strategies for each of the tools to gauge the tools’ sensitivities to the strategies that work for Iowa. Third, we will assess the results and applicability of the tools to wider use throughout the state. This will be a particularly useful test of the analysis tools since Iowa, like other rural states, experiences a different distribution of reliability problems than urban areas.