Green Line Extension to Medford & Union Sq

Observing multiple GL trolleys from Union Square turning back at Brattle Loop this afternoon. Super confused passengers departing and equally confused passengers being told to alight on the Brattle Loop track for Union Square service. Any idea what is going on?
 

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Observing multiple GL trolleys from Union Square turning back at Brattle Loop this afternoon. Super confused passengers departing and equally confused passengers being told to alight on the Brattle Loop track for Union Square service. Any idea what is going on?
It’s most likely because the D branch is closed for repairs. There is no other place for Union Square trains to terminate without causing delays.
 
It’s most likely because the D branch is closed for repairs. There is no other place for Union Square trains to terminate without causing delays.
Ah yes I see that D closure now with service resuming 12/21
 
It’s most likely because the D branch is closed for repairs. There is no other place for Union Square trains to terminate without causing delays.
Can I ask a stupid question? Why on earth can't this work on the tracks be done all at once, instead of having to shut down the lines multiple times?!! Seems so blasted annoying to have to go through all this hokey-pokey just to get a line finished once & for all!!! :(
 
Can I ask a stupid question? Why on earth can't this work on the tracks be done all at once, instead of having to shut down the lines multiple times?!! Seems so blasted annoying to have to go through all this hokey-pokey just to get a line finished once & for all!!! :(
I am very confused why the Green Line Trunk is being done in THREE separate closures. 11/27-12/5, 1/3 - 1/12, and 1/16 - 1/27. Why not just one long 30 day closure of the central subway tunnel?

It's especially the case since the first closure lifted 12 slow zones and allegedly saved 4 minutes of travel time, but the 4 minute travel time savings don't even show up in the TransitMatters dashboard for Green Line trip times.
 
I am very confused why the Green Line Trunk is being done in THREE separate closures. 11/27-12/5, 1/3 - 1/12, and 1/16 - 1/27. Why not just one long 30 day closure of the central subway tunnel?

It's especially the case since the first closure lifted 12 slow zones and allegedly saved 4 minutes of travel time, but the 4 minute travel time savings don't even show up in the TransitMatters dashboard for Green Line trip times.
Given the timing I'd guess there'd be a lot of lost time from holidays and workers on vacation anyway, plus they want to have it operational on NYE. I assume they're coordinating with the Government Center Garage demolition too.
 
Well the MBTA tried to tackle on an added promised fix to the GLX work, and then tried to make it disappear without anyone noticing. Same goes for the MBTA podcast they put up for 17 minutes one morning, and then they were made to try to take that down without anyone noticing.
About the podcast, Streetsblog confirmed that it’s takedown was simply because it was published before it was supposed to and for some reason the Governor’s office was very anal about it only being released exactly when agreed upon. There’s no difference in the releases as if they wanted to hide something or that they didn’t get to review it prior.

Also if anyone has better information chime in but I’m pretty sure all MBTA repair projects beyond basic MoW are contracted to a 3rd party private company. So the GLX blunders are on the private contractor(s) in this case GLXC. They promised the T who then promised the public and now Eng has expressed his disappointment in the contractor that they were unable to fulfill their promise.
 
but the 4 minute travel time savings don't even show up in the TransitMatters dashboard for Green Line trip times.
This is outdated information. TransitMatters dashboard does show travel time reduction in all 4 directions on the subway as of today:
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The last four weekdays have produced very consistent median travel times along the GL subway, and the only comparable travel times in November were on weekends and the Thanksgiving holidays, when there was lower ridership and hence shorter dwell times.

Possible reasons why such a trend did not show up in the days immediately following the reopening are:
  • The first few days after the opening saw a decreasing trend in trip times, likely due to teething issues or that drivers were not accustomed to the lack of slow zones. This trend was also seen on the Ashmont branch when it reopened.
  • Previous analyses may have paid too much attention to the Thanksgiving weekend, which immediately preceded the closure.
 
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This is outdated information. TransitMatters dashboard does show travel time reduction in all 4 directions on the subway as of today:
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The last four weekdays have produced very consistent median travel times along the GL subway, and the only comparable travel times in November were on weekends and the Thanksgiving holidays, when there was lower ridership and hence shorter dwell times.

Possible reasons why such a trend did not show up in the days immediately following the reopening are:
  • The first few days after the opening saw a decreasing trend in trip times, likely due to teething issues or that drivers were not accustomed to the lack of slow zones. This trend was also seen on the Ashmont branch when it reopened.
  • Previous analyses may have paid too much attention to the Thanksgiving weekend, which immediately preceded the closure.

Doing a 60-90 day period pre-closure to see. The slow zone lifitng was split between Blandford Street, as well as another slow zone lifting at Northeastern, outside of 2 or 3 in the central tunnel between Arlington and Boylston.

The time changes are only barely noticable, the data still seems somewhat messy.

Also, there needs to be a check of ridership if it decreases after Thanksgiving. It could influence the numbers. I'd think it's best to compare Sunday to Sunday numbers, since with less ridership to begin with that should give less volatility. Or compare Christmas Day to Thanksgiving Day (wait 2 more weeks).

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Are you sure? It's not reflected on the T's slow zone dashboard at all. Was it re-added?

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Yes, sorry I meant westbound from the perspective of the bridge/GLX, which is eastbound by the T’s definition in the tracker (and they should probably stop using east/westbound altogether since the GLX breaks that terminology with Medford/Tufts being west of Heath St).
The important thing is yesterday there were slow zones in both directions, now there’s only a slow zone in one direction.
 
Yes, sorry I meant westbound from the perspective of the bridge/GLX, which is eastbound by the T’s definition in the tracker (and they should probably stop using east/westbound altogether since the GLX breaks that terminology with Medford/Tufts being west of Heath St).
The important thing is yesterday there were slow zones in both directions, now there’s only a slow zone in one direction.
I cannot wait until the T implements Inbound/Outbound designations on the Urban Ring :unsure:
 
Isn’t it supposed to be 40 mph?
The technical specs for the GLX claimed 50 mph speeds between Medford/Tufts and Science Park, which implied but didn't explicitly say that the viaduct would support those speeds. The messaging from the T the last few years has been that 25 mph was the plan; it's not clear whether that was always the case and the GLX specs were just badly worded, or they're covering their asses.
 
The technical specs for the GLX claimed 50 mph speeds between Medford/Tufts and Science Park, which implied but didn't explicitly say that the viaduct would support those speeds. The messaging from the T the last few years has been that 25 mph was the plan; it's not clear whether that was always the case and the GLX specs were just badly worded, or they're covering their asses.
I don’t think the GLX specs could even apply to the viaduct since the viaduct was a separate project entirely - my guess is that 25mph was always the design speed for the viaduct and the GLX specs were never intended to apply to it even though they imply otherwise.
Speaking of those specs though, it’s interesting to see how they (haven’t) been followed in practice. The end of the viaduct to Lechmere is 25 or 30, I think most of Red bridge is 30 or 35, all switches are 10, and overall line speed seems to be limited to around 40. Does anyone have insight into why this is the case? Is increasing the line speed to 50 ever in the cards? Is the 10 mph over switches rule ever going to be lifted (even if it’s only once they get rid of the Type 8s)? The East Somerville to North Station portion is always disappointingly slow since there’s so many switches in that stretch.
 

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