How network structure can boost and shape the demand for bus transit
place - europe, place - urban, mode - bus, infrastructure - interchange/transfer, ridership - behaviour, ridership - growth, planning - network design, planning - travel demand management
Public transport, Bus system, Bus network design, Transfer-based network, Network effect
Conventional wisdom states that transit riders are averse to transfers and that consequently bus networks should be designed to limit their number. Probably as a result of this belief, many real bus systems try to connect as many origins and destinations as possible without transfers, so they are usually composed of long, circuitous routes with redundant overlapping sections – and the resulting bus map is hard to understand. If coverage is extensive, many routes are needed. Economics then prevents an agency from populating all routes with sufficient buses to provide attractively frequent service. This low frequency and the complicated circuitous map discourage transfers, perpetuating the belief that people are averse to transferring. Not surprisingly, the percentage of bus trips that includes a transfer has been reported to be: 1.5% for Boston, 3% for New York, 13% for London, and 16% for Melbourne.
The Nova Xarxa in Barcelona was designed with a different paradigm. It was designed and deployed to cover the whole city on the belief that if a bus map is easy to understand, and has direct lines with frequent service and ubiquitous transfer points then the bus system would become more appealing, people would transfer more freely and become users of the network rather than its single lines. With this design paradigm, a city can be covered with fewer lines, which can be depicted on a simple map. The lines can in turn be economically populated with sufficient buses to deliver the high frequency required to encourage transfers. Could this work?
To answer this question and see whether there is truth in the beliefs underlying the new paradigm, this paper examines data from the first three deployment phases of the Nova Xarxa (from 2012 to 2015). It is found that the Nova Xarxa is already attracting more demand than the network it replaced. This attests to its appeal. Furthermore, this demand has increased disproportionately with the number of lines opened for service in each phase, revealing that some people are using the Nova Xarxa as a network. The paper further shows that this growth is underpinned by transfers -- at the end of 2015, the percentage of trips that involved a transfer was approximately 26%, and it reached a maximum of 57% for line V7. These numbers should increase considerably (to 44% and 66%, respectively) once the Nova Xarxa is completed in 2018 and passengers have even more opportunities for transferring. The numbers disprove the conventional wisdom. They strongly suggest that transit providers can attract more demand by providing transfer-friendly networks that can be used as such and not as an inefficient aggregation of individual lines.
Permission to publish the abstract has been given by Elsevier, copyright remains with them.
Badia, H., Argote-Cabanero, J., & Daganzo, C.F. (2017). How network structure can boost and shape the demand for bus transit. Transportation Research Part A: Policy and Practice, Vol. 103, pp. 83-94.