Interchanges, Modal

Location and Distribution

The location of interchange stations, especially park-and-ride stations, is very critical in terms of the site, ease of access, and passenger perception. A number of studies have been undertaken to examine the mathematical relationship between different modes of transport in a network hierarchy. Clearly, the larger the urban area, the more modes of transport that can be supported, and are needed, provided they are arranged to interchange smoothly with each other. This modal relationship is also affected by the relationship of the speed of operation of each mode, and hence the practical minimum distance between adjacent stops on a particular line.

If a city is divided for transit supply purposes into a number of geographic zones, like hexagons, then normally each zone will justify one interchange station. The only other factor will then be the number of lines that serves each interchange and the catchment area served by those lines. If buses are assumed to be the lowest mode in the hierarchy, do bus lines only serve a particular zone, or do they [Page 824]cross zone boundaries? This is a problem for people living on zone boundaries. If bus lines only operate within a zone, then commuters may have to travel in the opposite direction to reach an interchange station, with a rail line linked to their ultimate destination. For many people this is counterintuitive. Cross-boundary bus services avoid this and also widen the market for transit.

The automobile made interchange station location in some ways easier and in other ways more difficult. If interchanges are located in the wrong place, commuters will drive all the way. So the location of interchanges must be based on a sound understanding of the travel market origin-destination pattern and commuters' perceptions of the ease or difficulty of interchanging. This is in addition to the fare structure and ticketing system, which impacts the utility of interchanges and the perception of the comparative cost of competing journey choices.

Number of Integrated Modes

Even in a city with competing modes of transport, like buses and taxis, it makes good sense for interchange stations to be provided, to enable modal cooperation, improve economic efficiency, and reduce environmental impacts. Sometimes interchanges may be provided by the operator of a higher order mode, (for example, rail) to encourage lower order modes to access and therefore “feed.” This will stimulate modal transfer, especially from car trips. Interchanges can also be provided by major facility providers like shopping malls, sports arenas, etc., to improve access to the facility, widen the catchment area, and also as an investment in the urban infrastructure. Finally, interchanges can be provided by the municipality as a civic facility to allow different operators and modes to integrate the local transit network with nontransit modes like car and bicycle.

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