The bicycle is a common mode of personal transport in many Third World cities (box 28.2), but the pedal cycle can also be the basis of public transport of people or goods, with many local variants of the bicycle with sidecar and the tricycle, The cyclos of Phnom Penh and the becaks of Indonesia have the passenger seat in front of the pedaller,while on the trishaws in Indian towns it is usually behind. Among the positive features of bicycle-based modes of transport are that over short distances in the rush hour, bicycles often provide the quickest form of transport and require relatively little parking space. Their use conserves energy resources and does not add to air pollution. Repairs are easily effected and the bicycle is suitable for a wide age range. In general terms of environmental impact, bicycles rate highly. On the other hand, bicycles and other non-motorised forms of transport are major contributors to urban road congestion