One of the most interesting and dramatic modifications to transport systems im the United States and other western countries is the "Freeway Revolt" movement that begun in the 1960s.

This movement resulted in the blocking of plans for further freeway expansion in many cities, and in many cases even the removal of existing freeways to convert the land used back to a more modest road network, and re-build the land released by this for other purposes (e.g. houses, retail shops, or public parks).

Whilst many people participated in the movement, one of the important early figures was Jane Jacobs, the community activist and intellectual who organised and played a leading role in blocking freeways in inner New York, particularly Greenwich Village.

Some good discussion of examples of freeway removal, and historical discussions of the movement, are available at:

• The removal of the Park East freeway in Milwaukee:- http://www.preservenet.com/freeways/FreewaysParkEast.html
• Several freeways cancelled or removed in Portland, Oregon:- http://web.archive.org/web/20170722035151/http://www.permatopia.com:80/wetlands/deadroad.html
• In central Seoul, the removal of a freeway and renewal of the Cheonggyecheon stream as a public park and cycle-way - see wikipedia:Cheonggyecheon, and Inhabitat article or Preservenet article.

See wikipedia:Freeway revolts for a fuller list of revolts that occurred.

For an image of the Park East demolition, seeI http://www.museumofthecity.org/assets/jmosteiro/park-east-freeway-demolition

Some reasons supporting a case for limiting the expansion of freeways, or removing them, in relation to urban sustainability are:

• Limiting the supply of high-capacity roadways will encourage people to limit their use of cars for long-distance travel, and either try to re-localise their transport, and/or use and demand better public transport alternatives. The latter are more efficient in terms of greenhouse gas emissions, and also generally produce considerably less air pollution, health hazards etc.
• Removing freeways should help reverse a trend towards very dispersed land-use that freeways promote, which tends to 'lock-in' long distance commuting in people's ways of life.
• The large structures that freeways represent tend to 'split up' neighbourhoods in cities, which makes them less attractive to walk or cycle in for local residents or visiting to the areas. So, removing freeways can be used as part of promoting more walkable, mixed use environments that allow people to live a higher quality of life with less travel involved.