Here's the kerfuffle between Brookline and the T:
http://www.boston.com/news/local/ar...ghts_but_t_isnt_along_for_the_ride/?page=full
I saw some Brookline Transportation Board meeting minutes from May that says the parties are talking again and the T has warmed up to the idea. Town appears to have long ago signed/sealed/delivered the traffic study Pesaturo was all pissy about in that article; I can't find it anywhere online, though. We know all too well "warm up to" ≠ "ready to fund", but that's a decided improvement over the dismissive tone they were taking before.
All the traffic lights on Beacon between city lines are computer-programmable from a central location. On the C it's just Cleveland Circle in Allston where that's not true. So the light cycles can be set to anything via software without field workers needing to be out there. And they've already got emergency vehicle prioritization that triggers those strobe light beacons on top of the signal masts.
To do transit vehicle priority they'd have to install the detectors, but the digital system and software are compatible with those out-of-the-box. Most common application is an optical detector that detects the shape of the bus or trolley and is just sensitive enough to tell a T bus apart from a private bus. For the trolleys the little sensor would just get mounted on top of the existing trolley signals pointing at the track.
Not too expensive. You're talking maybe $150K for the add-on hardware + labor + training to do up the whole corridor vs. the $2.3M the town sunk into the original signal replacements. There's also some legalities to work out about town-control signals with a state-control transit ROW to hash out so there's a way to mediate future disputes, plus a who-pays-for-what split on maintenance going forward. Basic inocuous red-tape stuff.
They just have to bloody do it. I mean, they announced it with fanfare for the 39 as a priority project and we're still waiting, waiting, waiting for it to get done.
BTW...here's some independent traffic modeling reading on what it would do for Beacon. Caution:
lots of hard maths.
http://iris.lib.neu.edu/cgi/viewcontent.cgi?article=1022&context=civil_eng_theses