Literature Review: Upgrading Roads and Congestion

Traffic congestion is a major problem in many urban areas around the world. It can cause delays, frustration, and increased pollution. One common solution to congestion is to upgrade roads, such as by widening them or adding lanes. However, there is growing evidence that upgrading roads does not always reduce congestion. In fact, it may even make it worse.

One of the main reasons why upgrading roads does not always reduce congestion is a phenomenon called traffic-induced demand. This occurs when people choose to drive more when they have more road space available. This is because driving becomes more convenient and attractive when there is less traffic.

Traffic-induced demand can be seen in a number of studies. For example, a study of highway widening in Los Angeles found that traffic increased by 3% to 10% after the widening projects were completed. Another study of highway widening in Seattle found that traffic increased by 10% to 20% after the projects were completed.

Traffic-induced demand can lead to a phenomenon called induced congestion. This occurs when more people driving on a road causes traffic to slow down, even if the road has been widened or lanes have been added.

Induced congestion can be seen in a number of cities. For example, in New York City, traffic speeds have decreased by 20% since the 1970s, even though the number of cars on the road has increased by 40%. Similarly, in London, traffic speeds have decreased by 15% since the 1990s, even though the number of cars on the road has increased by 25%.

There are a number of alternatives to upgrading roads that can be more effective at reducing congestion. These include:

1. Investing in public transportation. Public transportation can provide a more efficient and convenient way to travel, and it can reduce the number of cars on the road.
2. Encouraging walking and biking. Walking and biking are healthy and environmentally friendly ways to travel, and they can help to reduce congestion.
3. Implementing congestion pricing. Congestion pricing charges drivers a fee to use congested roads. This can discourage people from driving during peak hours, and it can raise revenue that can be used to invest in public transportation and other transportation alternatives.

Upgrading roads is not always the best solution to congestion. In fact, it may even make congestion worse. There are a number of alternatives to road upgrading that can be more effective at reducing congestion. These alternatives include investing in public transportation, encouraging walking and biking, and implementing congestion pricing.

References

• Brueckner, J. K. (2011). Roads and congestion. Journal of Economic Perspectives, 25(3), 157-180.
• Dowling, R., Skabrak, M., & Westerman, H. (2008). Traffic-induced demand: Evidence from nine US urban areas. Transportation Research Part A: General, 42(3), 464-476.
• Litman, T. (2003). Induced traffic demand and the highway lobby: A literature review. Victoria Transport Policy Institute.