Thread: MBTA Bus & BRT
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Old 07-15-2018, 04:55 PM   #566
Joel N. Weber II
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Join Date: Aug 2015
Posts: 587
Re: Mass Ave / Central Sq in Cambridge

Quote:
Originally Posted by Joel N. Weber II View Post
Essex St would get a traffic signal
On further thought, I think an Essex St traffic light would probably be overkill.

Instead, when a Harvard bound bus is approaching Pearl St, the Pearl St light could be set up to stop the right hand lane to store the automobiles that want to proceed on Mass Ave, and to give traffic in the left lane (the bus + left turns to Pearl St lane) a green light to proceed. At the same time, while a westbound bus is somewhere between Norfolk St and the bus stop at the Central Sq Red Line station and one or both westbound automobile lanes on Mass Ave just to the east of Prospect has one or more vehicles, the Prospect signal should give those lanes a green light to help vehicles get out of the way of the bus. (If Lyft and their competitors could be trusted to not use the travel lane between Pearl and Essex as a drop off lane, a westbound bus lane between Pearl and Essex might not even be needed.)

As a westbound bus clears the Pearl St intersection, the Pearl St intersection could switch to giving bicyclists some green time to delay giving the automobiles green time to give the bus a bit of extra time to merge right.

Ari's blog post proposed to use the currently unused space on Prospect just to the north of Mass Ave as a dedicated left turn lane for the 83 and 91 buses. I think it might be better to use that space to separate the right turn lane from the straight through lane; the Mass Ave / Prospect light would then normally go through three phases: proceed along Mass Ave, proceed along Prospect, and right turns. There would also be special phases triggered by transit signal priority for the 83/91 left turn from Prospect to Mass Ave (which would be simultaneous with automobiles proceeding south along Prospect, but northbound Prospect traffic would get a red light during that phase; this phase would probably also allow right turns from Prospect southbound to Mass Ave Harvard bound), and for the 64/70 left turn from Mass Ave to Prospect (also allowing Harvard bound automobiles to proceed along Mass Ave and probably also allowing right turns from westbound Mass Ave to northbound Prospect). [Edit: A third special phase which would allow westbound automobiles to proceed along Mass Ave and turn right onto Prospect while also allowing bicycles to proceed along Mass Ave and eastbound buses to proceed along Mass Ave could potentially be used to clear automobiles out of the way of buses approaching the westbound Central Sq bus stop.]

Last edited by Joel N. Weber II; 07-15-2018 at 05:06 PM.
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