Interstate Mobility Performance Scanning Tool
Motivated by multistate mobility performance management, especially for freight movement, GLRTOC has developed a monthly scanning tool utilizing data from the NPMRDS. Each month as new data are available, all 22+ thousand miles of interstate within the ten-state Mid-America region are scanned for anomalies. Through different methods and algorithms, major disruptions to mobility from incidents, new work zones, or winter weather are picked up, reported, and displayed on maps.
Data are established as a time series for each TMC (panel data), and various normalized Z scores are assessed, scanning for only the largest disruptions and anomalies. Borrowing from other disciplines, a control chart approach is applied to cull signals from noise, listening for anomalies of different durations and geographic extents. Short term dramatic reductions in speed – and especially observations – are symptomatic of major incidents and closures; longer term (e.g., multiple day) reductions in median or higher speeds often indicate high impact work zones; and widespread effects often signal winter weather impacts.
GLRTOC uses these results in their work to improve multistate mobility performance management. These presentation slides from June 2015 (PDF 4.7 MB) also show additional charts and illustrations.
The development of this continues, but some early examples follow. Scroll down for animated visualizations by different speed percentiles. Click on any image to see it larger and by itself. Individual images for each month and measure are listed at the bottom.
The following animation as an example of visualizing impacts by day. This one shows where significant drops in throughput occurred in February 2015 – note the winter weather on February 1st, the 5th snowiest day on record for the Chicago area.
Results by Month and Measure
Each month lists an image showing the 20th percentile speed score, 50th, and 80th, followed by the data count score.