Traffic congestion
From Freepedia
Traffic congestion occurs when the volume of traffic on a roadway is high enough to become detrimental to its performance. In congested conditions, vehicle speeds are reduced, increasing drive times. These conditions are also more frustrating for drivers (see road rage), and automobile accidents may be more frequent. Furthermore, vehicles burn unnecessary fuel when stuck at idle. A period of extreme traffic congestion is known as a traffic jam. Traffic engineers sometimes apply the rules of Fluid Dynamics to traffic flow, likening it to the flow of a fluid in a pipe.
Economist Anthony Downs, in his books Stuck in Traffic (1992) and Still Stuck in Traffic (2004), offers a dissenting view: rush hour traffic congestion is inevitable because of the benefits of having a relatively standard work day. In a market economy, goods can be allocated either by pricing (ability to pay) or by queueing (first-come first-serve); congestion is an example of the latter. Instead of the traffic engineer's solution of making a "pipe" large enough to accommodate the total demand for peak-hour vehicle travel, either by widening roadways or increasing "flow pressure" via automated highway systems, Downs advocates greater use of road pricing to reduce congestion, in turn plowing the revenues generated therefrom into public transportation projects.
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Traffic congestion in the United States
In the United States, construction of new highway capacity has not kept pace with increases in population and car use and the resulting increase in demand for highway travel. Between 1980 and 1999, the total length of highways as measured by miles increased by only 1.5 percent, while the total number of miles of vehicle travel increased by 76 percent.
The Texas Transportation Institute estimates that in 2000 the 75 largest metropolitan areas experienced 3.6 billion vehicle-hours of delay, resulting in 5.7 billion US gallons (21.6 billion liters) in wasted fuel and $67.5 billion in lost productivity. Traffic congestion is increasing in major cities, and delays are becoming more frequent in smaller cities and rural areas.
The five areas in the United States with the highest levels of traffic congestion are:
Due to dramatic population increases, San Diego and Las Vegas have seen their congestion levels increase by more than 50 percent since 1982.
Classification
The U.S. Department of Transportation uses the following scale, based on lane occupancy, to classify traffic congestion:
- 35% or higher: Stop and Go
- 22% - 35%: Heavy
- 15% - 22%: Moderate
- 0-15%: Wide Open
Attempts to alleviate traffic congestion
- Improvements of junctions
- Building new roads and widening of existing ones (this practice is criticised by proponents of the induced demand hypothesis)
- Road pricing, or tolls, such as the London Congestion Charge, a fee levied on vehicle drivers entering the centre of the city
- Cheaper and better public transport offered by the local or provincial government, see Public transport#Funding
- Setting of school opening times to avoid problems associated with the school run
- High-occupancy vehicle lanes or "carpool lanes"
- Quotas on the number of vehicles on the road. Examples are the fairly successful "cap and trade" method used in Singapore [1] and number plate restrictions on certain days of the week, as practiced in Athens and Mexico City.
- Traffic management and prevention of accidents
See also
- Congestion, for more general usage of the word congestion
- Gridlock
- Journey to work
- Queueing
- Rush hour
- Traffic break, the deliberate separation of traffic
- Traffic Message Channel, or TMC, a technology for broadcasting digital encoded traffic information.
