The Dorchester/Quincy Bottlenecks Discussion(s)

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The Dorchester/Quincy Bottlenecks Discussion(s)

Postby wicked » Sat Dec 21, 2013 8:22 am

So ... what realistically can be done to get this fixed?

Of the two, which is more important to get taken care of first? I'd say Dorchester.

Does the T feel like this is any bit important?
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Re: The Dorchester/Quincy Bottlenecks Discussion(s)

Postby daytripper1 » Sat Dec 21, 2013 11:15 am

Can you expound upon this a little more, please? Bottlenecks where specifically?
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Re: The Dorchester/Quincy Bottlenecks Discussion(s)

Postby wicked » Sat Dec 21, 2013 3:56 pm

Commuter rail lines to the South Shore, they run single track in an area where three lines are fighting for space to get through en route to South Station.
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Re: The Dorchester/Quincy Bottlenecks Discussion(s)

Postby highgreen215 » Sat Dec 21, 2013 6:14 pm

It may be expensive, but consideration should given to double-decking tracks.
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Re: The Dorchester/Quincy Bottlenecks Discussion(s)

Postby The EGE » Sat Dec 21, 2013 6:44 pm

The problem is that the Red Line was built first, and absolutely obliterated the ROW in many places. Wollaston is on this high grade with no room for expansion. Some of it is plausibly fixable - a one-platform JFK/UMass might allow for 2 tracks even without Southeast Expressway reconstruction (which would put some of the tracks in a tunnel). Some, nearly, isn't.

Here's a map of where the bottlenecks are. Note that both JFK/Umass and Quincy Center are single-tracked, as are the sections by most Red Line stations save North Quincy and Braintree.
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Re: The Dorchester/Quincy Bottlenecks Discussion(s)

Postby wicked » Sun Dec 22, 2013 6:33 am

To me, this (as well as our other transit foibles) is going to contribute to a stagnation of Boston's growth.

Every Middleborough train I ride on, and I'm on at least once a week, has 20-30 people get off in M'boro outbound. In mid-morning. Weekday or weekend. At the last stop. For an infrequent midday service. At a site with few other connections to public transit (sparse stops for the town shuttle, a connector bus to Wareham, that's it). It's near impossible to increase headways much -- not even considering equipment and funding issues -- without an upgrade of infrastructure between JFK and Braintree. Unless density increases massively inside the city and inner suburbs, which it won't (there's not a ton of room for that to happen), people are going to have to live in Middleborough because they can't afford anything else.
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Re: The Dorchester/Quincy Bottlenecks Discussion(s)

Postby midnight_ride » Sun Dec 22, 2013 1:23 pm

With the recent sale of the Boston Globe and talk of redevelopment of the newspaper's property on Morrissey Blvd. in Dorchester (adjacent to the Expressway and the Red Line and Old Colony tracks just south of JFK Umass) perhaps there is an opportunity for the state to acquire some of that parcel (whether through purchase, which could be prohibitively expensive, or through land swaps) and give both the ROW and the Expressway a little breathing room at that location.

Not how sure how the road or ROW could be rebuilt if such an outcome came to pass, but that Globe property seems like the only way to expand the railroad's footprint without taking houses.

Of course, that would only address the bottleneck from JFK to Savin Hill, so maybe it isn't even worth the expense if it only solves a small part of the problem.
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Re: The Dorchester/Quincy Bottlenecks Discussion(s)

Postby F-line to Dudley via Park » Sun Dec 22, 2013 1:27 pm

The Savin Hill pinch can probably get solved some day by burying the RL Braintree Branch under the Ashmont Branch. Demolish the Braintree flyover ramp just south of the JFK platforms and slip it into a shallow tunnel underneath Ashmont instead of passing overhead. Ashmont stays on the same footprint as before, but its roadbed is now the tunnel roof and power/cable for both branches are now consolidated in one location above/below. Savin Hill shouldn't be terribly difficult to structurally underpin for Braintree running underneath, the Old Colony takes its current track + claims the ex-Braintree outbound track, and 93 gets one track's worth of space to widen the breakdown lanes or something. Subway would spit Braintree back out to the surface in the vicinity of the old freight siding where 93 starts peeling away, angling under the Old Colony for a portal that retains the current track layout for points south. Ashmont would have to be shifted to the westerly slack space on the ROW and the Freeport St. bridge widened to 4 tracks to keep the Old Colony double track contiguous over the river. Ends up being 3000 ft. of shallow subwaying, give or take.

The state performed a study of this, but it was highway-centric about widening 93 for HOV lanes and clearly had no rail people involved because their solution involved tunneling the Old Colony instead...way more invasive because of the taller clearances and need to ventilate. I doubt that's going to fly if they re-study. Red-over-Red would be a hell of a lot cheaper and easier.



That solves one bottleneck, but it doesn't come anywhere close to solving them all.

-- There's still the matter of fitting double tracks through JFK station itself, and I don't know how that'll work without the 93 overpass being rebuilt to move abutments out of the way. I'm not sure if the pinch is too severe underneath to allow 2 CR tracks even if you did widen everywhere south. The Columbia Rd. bridge over Old Colony Ave. would also have to be widened, and Old Colony Ave. just north of the station shifted over a few feet. Reworking the station kiss-and-ride is the least of their concerns for shoving a second track through there.

-- Columbia Jct. itself is so incredibly wasteful on space a major rebuild is going to be necessary to compact that whole mess. Plus the Dorchester Ave., Boston St., and Southampton St. bridges would all need to be widened. Perhaps something like this crude drawing would help reduce its footprint. Has the added benefit of grouping all inbound and all outbound at 1 platform each to prevent the mad dash from the overpass to catch the right train, and retains most of the grade sepatation between the branches and the Cabot leads. Crossover placement negotiable, but from this layout I did in about 2 minutes the only conflicting movements are the Braintree/Ashmont inbound merge (same as today) and the Cabot outbound merge near the portal.

Columbia-revised.jpg
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-- Quincy has its own set of problems. Highly unlikely you could lay 2 CR tracks along Freeport St. between N. Quincy and Wollaston with the available space. Unless Red has give to shift a couple feet over to the retaining wall, the southbound CR crack can get shifted towards the road with the grass median eaten for a retaining wall and the sound wall moved a few feet, and Red + CR packed a little closer together. That still doesn't solve the squeeze at Wollaston Station, so it would only buy you another 1800 ft. of double before Wollaston and the Beale St. bridge.

-- Wollaston-Quincy Ctr. has similar constraints. You could maybe widen back to double-track after Beale St. with the same track-shifting tricks, but that only buys you 3500 ft. more before the Quincy Ctr. pinch at the Furnace Brook Pkwy. bridge. You would have to dig/underpin the intersection to overhang the track between Furnace Brook and Adams St., slightly widen the ROW for another 1200 ft., and then dig another overhang into the station to get a second platform berth and then out of the station. I'm guessing all of this is going to be impossible.

-- It's definitely impossible the entire 1-mile length of the cut out of Quincy Ctr. station along Burgin Parkway to Quincy Adams. You might be able to restart double track out the south end of Quincy Adams for 2000 ft. by widening the track underpass, the Route 3 onramp and Washington St. bridges, track-shifting the 1600 ft. between Washington and the Elm St. bridge, and widening the Route 3 overpass at the junction.



You get the idea. This is going to cost a billion dollars to do end-to-end and may be outright engineering-infeasible in Quincy. I think the best you're going to do is future Route 3 widening near the Braintree split likely taking care of that last bridge by the junction with the Greenbush Line allowing double track from the junction to Braintree Yard to eliminate the only daily freight interference. *Maybe* Savin Hill can get taken care of with Red-under-Red because MassHighway would probably chuck in to get some more I-93 breathing room, it would be easy tunneling akin to the Fields Corner-Ashmont shallow cover-over, and can save costs by laying Ashmont on top of the bare concrete roof, and the consolidation of both branches' physical plant substantially lowers maintenance costs. *Maybe* the T can shuffle stuff along Newport Ave. to bring the contiguous double track to the foot of Wollaston Station. And *Maybe* MassHighway will rebuild that very old JFK overpass on 93 to extend the zipper lane a little closer to Southampton and consolidate the abutments so a second CR track has room to go to an island platform.

But a total teardown/rebuild of Columbia Jct. is a low-value proposition. And Wollaston to Quincy Adams and the junction may just be outright physically impossible, with the Quincy Ctr. platform remaining a train meet bottleneck. I just don't know how they can justify the extreme price tag for either of these things. They may be stuck permantly with a 3/4 mile pinch between Southampton St. and Columbia Rd., and a 3-1/2 mile pinch from Wollaston to the junction with only 2000 ft. of double track infill at the south end, and 2000 ft. of infill north of Wollaston + 1-3/4 miles of infill in Dorchester to JFK to lengthen the existing double to 4-1/4 miles Dorchester-Quincy and 1-1/4 miles in Braintree. Every little bit helps, and any way of getting JFK a 2-track platform really helps with train meets, but almost half the mileage + Quincy Ctr. platform is likely to remain single tracked forever.
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Re: The Dorchester/Quincy Bottlenecks Discussion(s)

Postby wicked » Sun Dec 22, 2013 2:02 pm

I understand why, when it was built, that the Braintree branch split off before JFK.

But now that both lines stop at JFK, why couldn't you build a split off south of JFK? I'd assume this was studied before the Braintree platform was built at JFK?

You have room after getting past the Xway and before Savin Hill to do that, I'd think -- room according to the naked eye. Is it possible engineering-wise? You all would know better than me.

As far as Quincy Center, what method was used to build the commuter rail stop there? IIRC, that was ALL concrete before the Old Colony was restored. There must have been some serious blasting and reinforcing work done there.
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Re: The Dorchester/Quincy Bottlenecks Discussion(s)

Postby F-line to Dudley via Park » Sun Dec 22, 2013 2:15 pm

wicked wrote:I understand why, when it was built, that the Braintree branch split off before JFK.

But now that both lines stop at JFK, why couldn't you build a split off south of JFK? I'd assume this was studied before the Braintree platform was built at JFK?

You have room after getting past the Xway and before Savin Hill to do that, I'd think -- room according to the naked eye. Is it possible engineering-wise? You all would know better than me.

As far as Quincy Center, what method was used to build the commuter rail stop there? IIRC, that was ALL concrete before the Old Colony was restored. There must have been some serious blasting and reinforcing work done there.


Splitting off after JFK would worsen congestion and make the station another failure point where a disabled train can block ALL moves to or from downtown. The resiliency of a 4-tracker helps a lot, so I'm not sure that's a great idea. There's also large enough number of non-revenue moves coming out of Cabot that fluid, mostly grade-separated movements are beneficial.

They can split off earlier and not require such an enormously complex and sprawling Columbia Jct., however. Just by reordering the tracks outbound-outbound-inbound-inbound then using the flyovers south of the station to sort them all on their separate trajectories would probably eliminate half the concrete and switches at the junction. As well as making the twin island platforms at JFK worlds more coherent for passengers.

Compacting the RL also doesn't help the commuter rail that much because of the placement of the girders under the overpass. CR is boxed into its current footprint by a set of overpass girders, so swinging a 2nd track outside would require building a whole new side platform that's going to get uncomfortably close to the RL no matter how the RL is reconfigured. It's a lousy, obsolete mid-1950's era overpass that could be done a lot better with modern construction requiring fewer supports below.
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Re: The Dorchester/Quincy Bottlenecks Discussion(s)

Postby Charliemta » Sun Dec 22, 2013 3:32 pm

Make the Red Line 3 tracks from the malfunction Junction to south of Savin Hill Station. The third track would be used as an express for rush hour trains.

This would free up space for a two track Old Colony line.
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Re: The Dorchester/Quincy Bottlenecks Discussion(s)

Postby F-line to Dudley via Park » Mon Dec 23, 2013 7:22 am

Charliemta wrote:Make the Red Line 3 tracks from the malfunction Junction to south of Savin Hill Station. The third track would be used as an express for rush hour trains.

This would free up space for a two track Old Colony line.


Anything that hinders full RL capacity or introduces a new failure point before Columbia Jct. isn't a good idea. Reversible tracks are harder to dispatch than dedicated tracks, and if the line ever gets resignaled with CBTC to shorten downtown headways to as little as 3 minutes it's going to get more crowded down there. They need to preserve all 4 tracks and as much grade separation as possible while compacting the profile of it and simplifying Columbia Jct.


The bigger thing to consider re: train meets on the Old Colony is that it doesn't matter much if you're adding +1000 or +2000 ft. extensions of the double track. If it isn't joining two separate segments of double in the middle or leading to a double-track station it doesn't buy that much more upside for train meets. All it is is more running space before hitting the same meets. The most consequential changes of all that they could do is doubling up JFK and Quincy Ctr. Platform dwells are the ideal time for staging meets...or in limited-stop JFK's case, overtaking in the same direction. If they have to spend a kajillion dollars on something, structurally underpinning QC and pairing with MassHighway for a solution to the limited space @ JFK between overpass girders are the ones that are going to buy the most new schedule slots.

Do the stations first and the Savin Hill and/or Columbia Jct. reconfigurations matter because they'd be joining a double-track JFK with the next segment of double track down by Victory Rd. or up by Southampton Yard. Then you've got some substantial contiguous mileage of DT and the largely unsolvable Quincy/Braintree pinches don't matter much for flushing service full on the 3 branches. But can't really get ahead of ourselves with huge Dorchester-wide megaprojects or obsessing about Savin Hill. JFK and QC platforms dwarf all else in real-world capacity gains, and it's a project that can only be feasibly tackled in segments because of the enormity of it all and very different tasks to tackle on each discrete set of single track. The gains that brings in terms of new schedule slots is enough to satisfy growth for a few years and stagger out the other (very expensive) relocation projects in Dorchester into separate, more easily fundable projects. Plus, JFK and QC platforms are the two modifications that can most easily be done with zero Red Line disruption. Anything else and you're bustituting one or both of the branches for a long time or putting up with 2 years of perpetually disrupted service...per double track project area. That is an awful lot to absorb too fast too soon. So the 2 stations are the ones to go all-out advocating for first since the biggest overall service gains are there, the biggest bang-for-buck is there, and the least overall disruption is there.



EDIT: I forgot the south tip of the Amtrak runaround stretches all the way to the Boston St. overpass. If Amtrak can be bargained with to reconfigure Southampton effectively enough so the runaround all points south of the Southampton St. bridge can get ripped up you would have 4 track berths under the Boston St. and Southampton St. bridges to play with, be able to shift the Cabot Yard tracks over, move the junction with the mini-yard leading to Track 61 up a few hundred feet to split off of the next segment of DT and free up the rest of the required space, and buy another 1500 ft. of DT without having to blow up those two bridges. It doesn't solve the pinches anywhere south of there, and thus isn't consequential until JFK and Columbia Jct. are reconfigured, but it limits the bridge rebuilds to just Dot Ave. and Columbia Rd. instead of requiring all 4 to be nuked and rebuilt.

Fodder for another day, because again none of that matters until the stations are done. Then none of that matters until Columbia Jct. is redone to join JFK with contiguous DT all the way to South Station.
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Re: The Dorchester/Quincy Bottlenecks Discussion(s)

Postby Gerry6309 » Fri Dec 27, 2013 5:07 pm

Some interesting ideas here.

A big factor in the situation from North Quincy is the grade separation work involved in building the Red Line in that area. The right-of-way was four tracks wide from Freeport St. all the way to Washington St. From Freeport St. to Columbia Rd. (JFK), the building of the expressway cut down the ROW to only two tracks, but the MBTA had enough space to fit a third track when the Red Line - South Shore was built. That required replacing a concrete abutment of the Savin Hill Av. bridge with a narrower steel one. But from Freeport St onward to Washington Street there is enough room. My suggestion would be to rebuild most of the stretch with the Red Line outside the CR (like PATH and the PRR in Harrison, NJ.) Stations might have to move to accommodate this but Wollaston needs a major rebuild for ADA reasons and Quincy Center's garage has been condemned anyway! In its day, the Elevated could have done this type of work under service, today it would require months of busing! Go Figure - and add lots of zeros.

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