Evaluating the long-term impacts of bus-based park and ride

Many park and ride (P&R) schemes worldwide are based on rail transport, however there has also been substantial development of bus-based P&R in which an enhanced bus service operates between a P&R site and an urban centre. This has been particularly marked in Britain, often in historic cities (such as York, Oxford and Cambridge). Development of busways has also provided opportunities for complementary P&R development. Nonetheless, a net increase in passenger car unit (pcu)-kilometres may be observed, despite a reduction on the principal radial corridor. This is due to increased car-kilometres in catchment areas of P&R sites, but this simple additive approach to changes in pcu-km may not reflect overall impacts if pcu-km are removed from a congested urban corridor. By using monetised external cost per pcu-km for different road types and traffic conditions (such as those in ‘WebTAG’ guidance in Britain), the net effect can be expressed in economic terms. Presented here is a case study of the Chelmsford system, showing that a net economic benefit may be attained, even though a net increase in pcu-km has occurred. Energy savings through diversion of car occupant trips to the Cambridgeshire busway are also assessed