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The transportation system is the backbone of the regional economy and community - connecting people to places, workers to employers and goods to markets. Continued investments in the transportation network is critical to allow for the movement of freight and people.

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Explore Transportation Indicators


Traffic & Congestion

Traffic Volumes at Gateways

Traffic volumes at regional gateways refers to the number of vehicles crossing county boundaries on a typical day to enter or exit the nine-county San Francisco Bay Area.

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Travel Time Reliability

Transportation planners use what's known as a buffer time index, or BTI, to gauge the reliability of travel times along a given route. BTI is a measure of how much time (over and above the average travel time) a driver would have to budget to be 95 percent sure of arriving on time at his or her destination. BTI is expressed as a fraction of the average travel time: the lower the BTI, the more reliable the trip. This measure covers freeways only, as no comparable data are available for local streets or the transit network.

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Miles Traveled in Congestion

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.

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Time Spent in Congestion

Time spent in traffic congestion - also known as congested delay - refers to the number of minutes weekday travelers spend in congested conditions in which freeway speeds drop below 35 mph. Total delay, a companion measure, includes both congested delay and all other delay in which speeds are below the posted speed limit.

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The Vital Signs initiative is led by the Metropolitan Transportation Commission (MTC) and the Association of Bay Area Governments (ABAG).

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