Monitoring and Evaluating Transportation System Performance
Note: Further details on monitoring and evaluating transportation system performance in the National Capital Region may be found in the separate CMP Technical Report.
I-95 Corridor Coalition Vehicle Probe Project Traffic Monitoring
Since July 1, 2008, major roadways in the Metropolitan Washington area have been monitored under the I-95 Corridor Coalition Vehicle Probe Project (VPP). The primary goal of this project is to provide Coalition members with the ability to acquire reliable travel time & speed data for their roadways without the need for sensors and other hardware. The VPP surpassed the original expectations and also provided real-time & historical tools for operations and planning.
As an affiliate member of the Coalition, the National Capital Region Transportation Planning Board has been granted the access to the data collected in the Vehicle Probe Project. This is an innovative data source for both highway performance monitoring and regional planning. The continuous real-time speed and travel time data have been integrated into the Regional Integrated Transportation Information System (RITIS) and intensely used by the Metropolitan Area Transportation Operations Coordination (MATOC) program. The archived data is of particular interest of the TPB and a valuable source for congestion monitoring and evaluation for the Congestion Management Process and other purposes.
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Example of congestion profiling of the region's
5,500 directional miles of roads with VPP Data.
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As of June 30, 2015, the VPP monitors about 5,500 directional miles of roads in the TPB Planning Area, including 520 miles of the Interstate System, 2,160 miles of Non-Interstate National Highway System (NHS), and 2,820 miles of Non-NHS arterials; if categorized by freeway/arterial, this coverage includes 680 miles of freeways and 4,820 miles of arterials.
This VPP data source has become the major source of traffic monitoring for both freeways and arterials in the Washington region, transforming the way by which highway congestion and travel time reliability are analyzed and presented.
Information from the VPP is summarized in quarterly National Capital Region Congestion Reports (RCRs), published on a regional Congestion Dashboard. The Congestion Dashboard provides a regional summary of congestion and travel time reliability on our roadways. The VPP have enabled TPB to share such information in a more timely and frequent fashion – on a quarterly basis. This calls attention in particular to the need for and impacts of demand and operations management strategies as part of the CMP.
Freeway Monitoring Program
Freeways comprise the critical backbone of the region's roadway system, and provide the most important indicator of our overall system. This is the portion of the region's roadway system for which the most comprehensive data set is available.
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Example from the 2014 report
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The TPB's regional freeway monitoring program is based upon comprehensive aerial photography of the region's freeways. Peak period congestion is monitored on a once-every-three-years cycle during the am and pm peak periods. It provides a comprehensive data set of the region's freeway conditions and congestion.
The program and analysis provide the following information on the region's freeways:
- A summary is developed of the overall conditions of the region's freeways. This data is then analyzed to indicate the most congested freeway locations, trends over time, and identification of factors associated with the congested conditions.
- A technical report is also published.
- A summary and description is developed of the top congested freeway locations in the region (see map to right). Planning, congestion management, or construction activity at or near these locations is also indicated to show what is being done to address this congestion.
- Significant changes to congestion levels are noted at given locations or to the overall system, based on trend analysis over time, including where the impacts of previously implemented projects or congestion management strategies are notable.
- A summary of technical information is developed regarding how the freeway condition information was developed, as well as associated performance measures.
Regional Transportation Data Clearinghouse
TPB compiles roadway usage data as available, collected from the region's agencies and jurisdictions. These data may come from jurisdictions' regular traffic counting efforts, special studies, permanent count stations, or other sources.
The Regional Transportation Data Clearinghouse program transforms these data into a format associated with the region's travel demand forecasting model. Compiled data are also associated with the estimated capacity of links on the region's roadway network, providing the opportunity to calculate estimated volume-to-capacity (V/C) ratios, a widely-used performance measure.
Special Studies and Data Collection Efforts
The TPB and its member agencies undertake special studies or data collection efforts, on both one-time and recurring bases. Examples include monitoring of high-occupancy vehicle (HOV) systems, airport ground access travel times, transit usage, and cordon counts of traffic on specified areas of the region.
Defining and Analyzing Strategies
This component involves identifying existing and potential strategies by the TPB Technical Committee, subcommittees, and staff. The TPB considers a number of demand management and operational management strategies.
To define and analyze CMP strategies, the TPB's efforts consist of compiling and analyzing information for each of the following strategies:
Committees and staff identifying and advising the TPB on the analysis, methods, criteria, and performance measures used to analyze CMP strategies.
Compiling information on how and where a particular CMP strategy has been implemented.
Identifying a strategy as regional, corridor-wide, or local.
Performing qualitative or, if possible, quantitative analysis of the potential impacts of CMP strategies
Compiling information on potential impacts of strategies into summaries such as a “short list” and “long list.”
Implementing Strategies
This TPB effort is to focus on compiling information on strategies that have been implemented, particularly on a region-level basis. Also, the TPB is exploring how to assess previously implemented strategies. Feedback from the process is beneficial when it comes to updating the CMP and considering additional strategies and technical methods.
TPB currently reports on results of regional strategies implemented through the Commuter Connections Program.
Compiling Project-Specific Congestion Management Information
Pursuant to Federal regulations, the TPB encourages consideration and inclusion of congestion management strategies in all SOV capacity-increasing projects. This involves compiling and analyzing information in the Call for Projects documentation forms, which are submitted from regional agencies when the CLRP is developed.
The Call for Projects documentation requests any project-specific information available on congestion that necessitates or impacts the proposed project. Agencies compile this information from various sources, including TPB-published congestion information (if available), internal or other directly measured information, or by conducting engineering estimates of the Level of Service (LOS). TPB compiles and analyzes this submitted information, along with information from other CMP sources.
Specifically for SOV capacity-increasing projects, the TPB requests documentation that the implementing agency considered all appropriate systems and demand management alternatives to the SOV capacity. In the Call for Projects documentation a special set of SOV questions is completed by implementing agencies and the TPB compiles this information.