Urban transport in the largest Latin American and Caribbean cities consumes about 3.5% of regional GDP — a percentage that is inflated by the effects of traffic congestion. In addition to the costs of congestion in terms of lost economic efficiency, there are also negative consequences in terms of social cohesion. The phenomenon of traffic congestion, which is caused mainly by relatively wealthy car drivers, lengthens journey times and, more importantly, forces up public transport fares. Owning a car is one of the fruits of human progress; using it in conditions of acute congestion or contamination is a social ill.