Traffic Congestion
Description:
Simply, highway congestion results when traffic demand approaches or exceeds the available capacity of the highway system. While this is a simple concept, it is not constant. Traffic demands vary significantly depending on the season of the year, the day of the week, and even the time of day. Also, the capacity, often mistaken as constant, can change because of weather, work zones, traffic incidents, or other non-recurring events.
Characterisitcs:
- Congestion results in 5.7 billion person hours of delay annually in the United States.
- Between 1980 and 1999, route miles of highways increased 1.5 percent while vehicle miles of travel grew by 76 percent. By 2000 over 42,500 miles of highways in the 50 states and the District of Columbia were congested in 2000 (as defined by vehicle/service ratios of 0.8 or higher). Over 6,000 of these miles were in rural areas.
- FHWA forecasts that freight transportation will nearly double in the next twenty years, placing additional burdens on intermodal connectors, international gateways, and other parts of the highway system.
- Texas Transportation Institute (TTI) estimates that within major U.S. urban areas, over 32% of our daily travel occurs within congested conditions – and the trend continues to climb. In small urban areas alone (<500,000 population), congested travel increased 300% between 1982-1997.
- This congestion adds up to 4.5 billion hours of delay in 68 urban areas studied by TTI in 1999. Annual delay per person was 36 hours per year. The delay is 41 hours per person per year in cities over 3 million population. In the worst metropolitan area, Los Angeles, the delay was 56 hours per person per year. Between 1982 and 1999 annual delay per person in the 68 metropolitan areas increased at a compound rate of 7 percent (from 11 to 36 hours).
- Highway congestion is not just a problem of recurring "rush hour" delay in major cities. TTI estimates that delay due to incidents such, as breakdowns and crashes is slightly larger than delay due to peak period commuting in 68 cities. Oak Ridge National Laboratory estimates that nationwide the delay caused by work zones on freeways and by snow, ice, and fog is greater than delay from breakdowns and crashes. If delay caused by poorly timed traffic signals is added to incident delay, the total increases by 30 percent. These estimates do not include delay caused by special events (from sports venues to symphony concerts), rain, rail-highway grade crossings, toll booths, and work zones on arterials other than freeways, nor do these estimates include the significant delay which can occur in small cities and rural areas, especially in popular recreational locations and on heavily traveled intercity highways.
- The individual cost of congestion exceeded $900 per driver in 1997, resulting in over $72 billion in lost wages and wasted fuel.
- Work zones, bad weather, and other conditions not only cause delay; they create safety problems that threaten life and property.