Once more into the bus/rail breech, my friends.

In various comments and articles, I’ve enumerated various advantages that bus rapid transit has over equivalent-service rail in some circumstances; this post is simply a collection of these. It doesn’t constitute an endorsement of bus over rail for any specific project or system, hence the word “may” in the title–that analysis needs to be done on a case-by-case basis. And this is a one-sided post; the corresponding advantages that rail has over bus are not listed. Not because they don’t exist or are not important, but simply because I wanted to collect many of the good technical pro-bus arguments in one place. (I’m limiting myself to technical arguments for the most part; sociological or political arguments such as “trains cause gentrification” or “rail is just pork for developers” are not included).

A bit of terminology: This article refers to “Class A”, “Class B”, and “Class C” transitways, which refer to the isolation of the transitway from other traffic. Very roughly:

Class A is a grade-separated transitway (or one with absolute crossing priority), such as the various freeway-adjacent sections of MAX, and much of the Blue Line between Beaverton and Hillsboro. There are no examples of class A bus in the Pacific Northwest; North American examples can be found in Ottawa and Pittsburgh.

Class B is surface operation in an exclusive right of way where the transit vehicle may need to stop at crossings, such as MAX through downtown, along Interstate and Burnside, and in downtown Hillsboro. Much of the EmX line in Eugene is an example of Class B BRT.

Class C is ordinary mixed traffic operation–such as the bulk of TriMet’s bus operations as well as the Portland Streetcar. Generally, plain class C bus is not considered BRT, but a type of bus service that is is commonly referred to as class C+ bus (or by other names such as “rapid bus”)–this refers to mixed traffic bus that enjoys enough enhancements (off-board fare collection, all-door boarding, signal priority, limited stop spacing, prominent stops) that it is a materially better product than local bus. Mixed-traffic streetcar systems can also have signal priority (and be class C+); the Portland Streetcar does not do this however.

A claim was made in a thread at Human Transit that for class A and B operation, rail is almost always preferable; this is a partial rebuttal to that, but the content is important enough to emphasize that it deserves a post of its own.

After the jump…

The reasons

BRT enjoys these advantages over rail: