The transport problem of Third World cities derive in large measure from their rapid transition from the 'walking' to the 'rubber' city form often without the development of the tracked transport associated with the expansion of cities in advanced economies. In most Third World cities, expansion has been based on road transport, but in a situation where vehicular traffic competes for road space with walkers, hand carts and animal-drawn vehicles, which take up considerable space in relation to their carrying capacity, and consequently determine the overall speed of movement over large areas of the city. The speed of the transition from 'walking cities' to the automobile ear has meant that, in contrast to cities of the industrialised world, few Third World cities had an opportunity to develop an urban public-transport system. The compact urban form of many Third World cities would appear to be well suited to public transport. However, increasing urban sprawl reduces the advantage of public transport and limits access, especially for those who occupy peri-urban settlements beyond the range of existing systems.