While this thread does contain a little bit of sparring over whether Siver Line Phase III is a good idea or not, there doesn't seem to be much discussion of the viability of BRT in Boston in general.
Examples of successful BRT systems all look to have benefited from simple existing road-infrastructure systems (wide streets in a grid pattern) or from inclusion in new projects built in open space (dedicated lanes along highways between urban nodes). These conditions just don't exist to a meaningful extent in Boston.
My questions for the board are:
-Have the portions of the SL already implemented been a success?
and
-Is BRT a realistic solution to any specific or general transit issues in the Boston area?
In my opinion, the answer to both of these questions just may be no.
I think the possibility is there that positive ridership numbers for the SL are a mirage in that they reflect a local culture committed to the use of public transit even when the transit options presented to them are sub-optimal. Just as many MBTA riders may take the subway downtown to avoid multi-bus trips between suburbs, or may take several buses to avoid congested subway conditions, some Sl riders may be arbitrarily choosing one of several transit options which don't quite actually meet their needs.
To be effective, BRT may require infrastructure that just does not fit into the fabric of central Boston. Accepting that an ideally functioning BRT system is cheaper to operate and more versatile than rail, with a higher rider capacity than bus, it needs to be examined whether to be effective, BRT may require infrastructure that just does not fit into the fabric of central Boston. Do estimates of BRT rider capacity hold up when huge articulated buses become stuck in traffic? Do cost assessments include the maintenance of a reserve fleet of standard buses to replace BRT service in adverse weather?
Points raised in the discussion of the impracticalities of the SL Phase III tunnel though downtown are applicable to other potential BRT routes such as the BRTification of the CT2, and BRT routes through the Longwood medical area. The neighborhoods these routes are meant to pass through consist largely of low capacity residential streets with no room for dedicated or grade-separated bus lanes.
An effective transit system requires the integration of different services, but BRT seems to be some people's answer on the table for addressing Boston's transit issues. BRT regularly works its way into discussion of existing rail projects like the Medford Green Line extension and the still mostly hypothetical "urban ring".
BRT looks like a square peg for the round hole of our transit planning questions...