Design of Zonal Express Bus Services to Reduce User Travel Time and Transfers Considering Demand Diversion

Zonal express is an operational strategy for express transit service that only stops in the initial and final zones of its route while skipping stops in-between. Zonal express provides a service with less travel and transfer time by aggregating trip demands with similar origins, destinations, and departure times. In this study, new zonal express routes are designed to reduce the travel and transfer times of transit users efficiently. This study develops a methodology that considers demand diversion. To meet the purpose, the following are conducted: (1) estimation of zonal express demand; (2) clustering of demand with similar origins, destinations, and departure times; (3) selection of candidate clusters; (4) optimization of stops and routes of zonal express; and (5) determining zonal express routes in which the benefit from reduced time and transfers outweighs the cost. The methodology is applied to an actual transportation network in Seoul, South Korea, using smartcard, car navigation, and spatial information data. The result shows that zonal express can reduce users’ travel time and the number of transfers effectively. This study proposes that it is desirable to introduce the zonal express sequentially from the route with the highest net benefit under a budget constraint. This study also presents the results when fares change to provide implications for pricing strategies of the zonal express. Future studies can consider incorporating various objective functions or utilizing vehicles in different time slots.