You hear it all the time. Buses are more flexible than rail. From point A, bus routes can take you to your favorite points X, Y, and Z, each in a single ride. They can detour around an accident. The routes can be altered to accord with population shifts.
But the curse of flexibility is that it gets used. It sounds like a truism, but bear with me. I believe the theme applies rather broadly, but I want to talk about the curse of transit flexibility.
The other day I was at the University of Waterloo after 7 pm and had to unexpectedly make it to downtown Kitchener. The 8 bus could get me there, but it was running at a 30 minute frequency. By that hour the 7 was running at a 30 minute frequency, on just one of its routings. The iXpress had the furthest stop and at that hour was also at a 30 minute frequency. I had the luxury of a choice between three different buses with separate schedules and bus stops — and infrequent service. Had the iXpress been running at a 10 minute frequency, I would’ve gone to that stop and not have wasted my time and energy trying to plan such a simple trip.
In contrast, transit infrastructure like light rail forces a choice of a corridor — and that’s where the service is concentrated, without being diffused among many routes.
Buses can detour. For some time this week road construction closed the north UW campus entrance, and separate construction closed the east side of Ring Road. That meant hell for transit users, who first had the realization that their bus wasn’t where they expect it, then had to figure out where it actually was, and of course the schedules were screwed up anyway. The iXpress did a detour of over 3 km between the UW stop and the R&T Park stop, taking a long time and getting stuck in the construction-related traffic along the way. Getting out and walking that same distance would have been faster.
Light rail can’t detour, so it forces construction to be done quickly, with minimal impact — and at night whenever possible.
Buses can have their routes moved in accordance with change in transportation demand, and the flip side is the absence of commitment that transit along a corridor will be provided in the years to come. So the location of transit routes cannot be used to directly inform decisions about where to live, or where to build. If you build fixed transit infrastructure (e.g. light rail), however, it’s a self-fulfilling prophecy. There is a tangible commitment to providing transit along that corridor, which is used to determine where to live and where to build, thereby itself shaping the transportation demand.
Precisely due to their flexibility, buses can do little to shape or direct urban form and land use. So they have no choice but to react. They can demand little of any forces that hinder their operations. And a bus system’s flexibility in providing service from any point to any other point makes it difficult to consolidate service into select, high quality routes that are easy to understand and use.