The impact of different organizational forms of road public transport on distance covered and atmospheric pollution

The operation of road public transport services that minimize pollutants emissions plays a key role in improving air quality in urban areas, so that considerable financial resources are employed to buy buses with innovative propulsive systems. However municipalities in poorer countries might not have sufficient funds to endow their fleets with such vehicles. In this paper we assess the possibility of lowering distances travelled and emissions by changing the organizational form of the service. We consider a traditional bus service and a demand responsive service using buses or vans, and we identify the best system for every combination of levels of demand and of service quality, as concerns travels and emissions minimisation. The analysis is repeated for different urban patterns and street networks. Results indicate that the use of a demand responsive service can lower distances covered when the demand is quite low but a good quality is required, provided that service requests are known in advance. Furthermore, the utilization of smaller vans with lower emission factors can give substantial benefits concerning atmospheric pollution, with an increase of kilometres travelled that is often negligible.