Major CMP Components

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.

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. 

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.
• Off-peak and weekend traffic conditions are monitored once every five years.

Arterial Monitoring Program 

The TPB's regional Arterial Monitoring Program is based upon travel time information collected on a sample basis on a number of the region's non-freeway arterial highways.

Example from 2010 Arterial Monitoring Report. Click image to enlarge.

The Program provides a data set of the region's arterial conditions and congestion. A sample of the arterials is taken, as there are thousands of miles of arterial highways in the region, and a comprehensive data collection effort would be cost-prohibitive. The data collection is limited to a number of important arterials, including the National Highway System (NHS).

From these data, a summary of the overall conditions of the region's monitored arterials is produced. These are categorized into a number of key types of urban situations. Examples from the data set are analyzed to illustrate the types of and reasons for arterial congestion in the region. As data are available, trends over time are shown.

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 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, transit usage, and cordon counts of traffic on specified areas of the region.

Emerging Data Sources: National and Private Sector Efforts

Example congestion summary graphics based on emerging private sector probe data (2010 CMP Technical Report - data are for a limited sample of the region's roadways)

Since July 1, 2008, a portion of freeways and major arterials in the Metropolitan Washington Area has been monitored by the I-95 Corridor Coalition's Vehicle Probe Project. This project is a groundbreaking initiative and collaborative effort among the Coalition, University of Maryland and INRIX, Inc. providing comprehensive and continuous real-time travel information to members. The objective of this project is to acquire travel times and speeds on freeways and arterials using probe technology. While the dominant source of data is obtained from fleet systems that use GPS to monitor vehicle location, speed, and trajectory, other data sources such as sensors may also be used. The INRIX system fuses data from various sources to present a comprehensive picture of traffic flow. This is the first time that such a comprehensive data set has been available nationally and for the National Capital Region.

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, as well as for validation of the regional travel forecasting model.

Analyses to date of the limited probe data available for the region has shown great promise as this data source is developed. Probe data will be used effectively to explore the reliability of traffic conditions, addressing the CMP's need to look at non-recurring congestion due to incidents, construction, or weather events.

 Another recent effort that is providing new traffic data is the Federal Highway Administration's Transportation Technology Innovation and Demonstration (TTID) Program, which was implemented under the SAFETEA-LU legislation. The TTID program has completed systems in a number of major metropolitan areas, including the National Capital Region. Location-fixed detectors are the primary data collection devices and about 190 centerline miles of freeways in the region are covered by this program. The advantage of this data source lies in the continuous traffic speeds and volume information obtained from the detectors. This data source will be utilized in the future to evaluate regional congestion.

Information from these emerging data sources 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 delay on our roadways. Emerging data sources 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.

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.