Metropolitan Freeway System Congestion Summary Report

The annual Congestion Study is a geographical illustration of the metropolitan freeway system's traffic performance. It portrays time and areas of congested traffic flow during the A.M. and P .M. peak periods.

Congested areas are determined from data gathered by traffic management sensor arrays. The data, five-minute volumes and lane occupancy values, provide input into the determination of the average five-minute running speeds per lane.

This report is a summary of the time a freeway operates below 45 miles per hour. Freeway system field observations indicate that under this condition, shock waves develop in the traffic flow. Our working definition of congestion is then traffic flow below 45 miles per hour. The data summary compares the traffic during the month of October in each of the years. This is done to minimize the effects of construction and maintenance-induced congestion and to account for school-induced traffic loads. The study uses 1993 as a base year, the first year the report was done.