The Congestion Management Process (CMP) is a federal requirement that provides a systematic framework for analyzing and managing recurring congestion and for incorporating congestion management into the planning process. As part of the CMP, the Capital Area Metropolitan Planning Organization (CAMPO) – which represents six counties in Central Texas (near Austin) – has conducted a Roadway Congestion Analysis every two years. For past analyses, CAMPO utilized the floating car method to gather travel time and speed data.
For the 2012 version of the CMP, CAMPO decided to use data provided from third-parties who aggregate data from a variety of sources, including remote GPS sensors. The project included an independent review of proposals solicited from an RFP, which included a critical assessment of data validity and robustness. Additionally, data were collected through the use of an Anonymous Wireless Address Matching (AWAM) system supported by Bluetooth-equipped sensors placed on the side of the road. Data were collected by the AWAM system for roadways that could not be provided by third-party sources.
Performance measures were introduced to help describe the four dimensions of congestion: intensity, duration, extent, and variability. The major performance measures selected for the plan (after consultation with CAMPO staff) was the travel time index, 80th and 95th planning time indices, delay per mile (measured in minutes per mile), and total delay (measured in vehicle-hours of delay). Each measure in the dataset was calculated for pre-defined roadway segments that were bounded by endpoints located at major roadway crossings – such as an arterial crossing an Interstate. The data sources used in the project did not have the same definition or the same endpoints. A GIS-based conflation process was developed to splice the roadway segments that defined the speed and volume datasets to create the reporting segments. To calculate the performance measures, the speed data for each segment were volume weighted so that a low volume roadway experiencing very slow speeds could be better compared to a high volume roadway with slow speeds. CAMPO intends to use the results from the CMP toward modeling future long-range plans.