Bus lanes are a useful traffic management measure in third world cities, particularly as the use of buses is high and often rising. Bus lanes are typically expected to reduce congestion and shorten bus journey times, but there is usually little attempt to monitor their full impacts. Bus lanes were introduced in Bangkok in 1980. Surveys carried out on six diverse sections, before and after the event, showed that in almost all cases, either bus travel times or car travel times, or both, were improved significantly. The most successful section showed improvements to both bus and car mean travel times of 25-30 per cent. On none of the sections were either bus or car travel times made worse. The bus flows observed in the study were very high, with up to 250 state-owned buses and 150 private minibuses using a single bus lane in an average peak hour. The initial bus lane regulations did not permit buses to leave the lanes. This increased bus bunching and therefore congestion at bus-stops, resulting in buses having to stop for longer to serve a given number of passengers. However this drawback was usually not sufficient to offset the general improvements to bus running times. Bus and car travel time surveys were repeated on one bus lane only, about one year after the first set of surveys. The results showed that nearly half the buses were running outside the bus lane. This caused a further reduction to bus travel times by allowing buses to overtake others. Car travel times were made somewhat greater but remained substantially less than before the bus lanes were introduced. (Author/publisher)
Samenvatting