Vital Signs: Miles Traveled in Congestion - by county

VITAL SIGNS INDICATOR Miles Traveled in Congestion (T8) FULL MEASURE NAME Congested share of total freeway vehicle miles traveled LAST UPDATED April 2017 DESCRIPTION Miles traveled in congestion reflects the share of miles traveled on regional freeways in congestion for a typical weekday; it is often referred to as the congested share of freeway miles driven also referred to as vehicle miles traveled, or VMT). Congestion is defined as speeds less than 35 mph, the level at which freeway throughput is maximized. The dataset includes regional and county tables for congested share of freeway miles driven. DATA SOURCE MTC/Caltrans: Performance Monitoring System (PeMS) Congested Mileage Analysis 2004-2016 CONTACT INFORMATION [e-mail] METHODOLOGY NOTES (across all datasets for this indicator) Congested VMT data only includes freeway facilities and relies upon PeMS traffic data. They reflect delay on a typical weekday, which is defined as Tuesday through Thursday during peak traffic months. Delay statistics emphasize recurring delay - i.e. consistent delay greater than 15 minutes on a specific freeway segment. Congested delay is defined as congestion occurring with speeds less than 35 mph and is commonly recognized as inefficient delay (meaning that the freeway corridor is operating at speeds low enough to reduce throughput - as opposed to speeds greater than 35 mph which increase throughput).