Green Line Extension to Medford & Union Sq

^Note the track alignment simplification in that graphic too
 
CSTH said:
^Note the track alignment simplification in that graphic too
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CSTH -- good observation -- that's the kind of VE that leaves the functionality but can dramatically reduce the cost just in terms of the amount of earth that has to be moved, walls to be built and even moving existing tracks

For example that latter aspect could mean temporary one-tracking while the other track is moved, and that in turn could dramatically reduce the limitations on working hours, etc.

I wonder if the use of a central pole system for supporting the overhead wires [as mentioned for the redesign of the stations] could mean an even further shrink on the GL side, perhaps even obviating the need to do any significant digging into that side of the cut

It's also interesting that our local T experts have not commented on these kinds of cost reductions
 
bigeman312 said:
I love this. But it seems too good to be true. What's the downside?
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The Lowell Line suggestions are big. But may require additional surface and subsurface right of way. Some work to date may be incompatible.

A lot of the rest of the savings are basically -- defer this aspect -- build it later. Eliminating things like headhouse (and fare collection), which won't work due to the traffic projections. GLX needs all door boarding.
 
Here's the full 12/09/15 Arup report for anyone interested: http://www.mbta.com/uploadedfiles/A...E MassDOT and FMC Boards ISSUE FINAL copy.pdf

Professionals panned the report as being too vague, but Arup didn't have very much time to prepare the report in the first place. It was prepared in a rush for the FMCB.

Value Engineering and Cost Reduction Opportunities

No. | Description | % of Project Construction Cost
1 New Lowell Line Cross-Section ~ 40%
2 Scaled Down Stations ~ 23%
3 Union Square Branch Alternatives ~ 15%
4 Viaduct Redesign ~ 12%
5 Downsized Vehicle Maintenance Facility ~ 11%
6 Schedule and Productivity Improvements ~ 8%

Range of Potential Savings: 10% to 40% of Construction Cost
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Lowell Line Cross-Section Opportunities

Reduce proposed cross-sectional width

Eliminate utility corridor
• Relocate AC power to catenary
• Relocate Community Path to combination of north side and
outside of the active rail corridor

Apply fewer and more economical retaining walls
• Purchase sub-surface easements

Associated reduction of quantities for:
• Commuter Rail tracks
• Bridges
• Utilities/drainage
• Systems
• Site works
Click to expand...
 
bigeman312 said:
I love this. But it seems too good to be true. What's the downside?
Click to expand...

Biggeman -- Seems only to be getting some Somerville Community Activists angry -- specifically those who were hammering for the fancy "Community Path"

All that is needed at this stage is to scrape away a bit of the hillside, pour some asphalt and low and behold you have the basic'Community Path" -- if later Sommerville wants to make it more fancy ---Well, that's their own cost and responsibility
 
datadyne007 said:
Here's the full 12/09/15 Arup report for anyone interested: http://www.mbta.com/uploadedfiles/A...E MassDOT and FMC Boards ISSUE FINAL copy.pdf

Professionals panned the report as being too vague, but Arup didn't have very much time to prepare the report in the first place. It was prepared in a rush for the FMCB.
Click to expand...

Data -- it looks as if they have 90 days now [perhaps back dated to Dec 15] to work on a much more complete version -- but what they have identified looks promising
 
Looks like they shrunk the size and cost of the retaining walls... by adding a ski slope to the back yards of all the abutters. You can't just do that without purchasing the land or a slope easement, and there are several buildings that but right up to the right-of-way that would need to be torn down. There's more room to work with on the south side, but that's already a pretty steep slope there and I'm not sure you could make it any steeper.

The others savings would come from keeping one set of tracks in place. I'd like to think it's possible to save a few hundred million by doing that, but I'm guessing the savings is probably more like a few million at most.
 
Given what went down on this thread over the last several weeks, I feel a responsibility to post the last slide of that presentation here as well:

24584710856_fee962e152_b.jpg
 
whighlander said:
perhaps with the replacement of the Union Square GLX with some sort of CR Station at Union Square
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Wouldn't the removal of one spur be considered a large change of scope, potentially endangering the Federal Funding? New Start grants include economic development as part of the evaluation process.
 
Texasian said:
Wouldn't the removal of one spur be considered a large change of scope, potentially endangering the Federal Funding? New Start grants include economic development as part of the evaluation process.
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Obviously, MassDOT would prefer not to trigger a federal reconsideration. For Maryland's Purple Line light rail, they were able to cut headways, fleet size (and reduce storage yards).

But the FTA also considers costs per new rider and--as Arup hints--Washington St and Union Sq kinda cannibalize each other being so close together.

I'm glad Arup raised the idea of a single-track shuttle to USq. Recall that Union Square was not part of the CLF/State agreement that mandated an extension to Medford Hillside (Tufts)

Obviously, Arup knows their stuff. I'm happy they at least flagged all the station cost-issues that we've discussed here.

I was surprised (and relieved) to see how much might come from not having the Lowell Line cross section so wide at the bottom (it looks like it was padded both between the GLX tracks and again between the GLX and the CR.
 
Arlington said:
Obviously, MassDOT would prefer not to trigger a federal reconsideration. For Maryland's Purple Line light rail, they were able to cut headways, fleet size (and reduce storage yards).

But the FTA also considers costs per new rider and--as Arup hints--Washington St and Union Sq kinda cannibalize each other being so close together.

I'm glad Arup raised the idea of a single-track shuttle to USq. Recall that Union Square was not part of the CLF/State agreement that mandated an extension to Medford Hillside (Tufts)

Obviously, Arup knows their stuff. I'm happy they at least flagged all the station cost-issues that we've discussed here.

I was surprised (and relieved) to see how much might come from not having the Lowell Line cross section so wide at the bottom (it looks like it was padded both between the GLX tracks and again between the GLX and the CR.
Click to expand...

I wondered since the start of this, what were the projected headways for the union square branch? It seems like there would be relatively few trains going down that branch.

Basically would it be quicker for someone to get on a shuttle train that is pinging between lechmere and union and then transfer than for them to wait for a train at union under the current plan?
 
Mongo said:
I wondered since the start of this, what were the projected headways for the union square branch? It seems like there would be relatively few trains going down that branch.

Basically would it be quicker for someone to get on a shuttle train that is pinging between lechmere and union and then transfer than for them to wait for a train at union under the current plan?
Click to expand...

Funny you ask. GLX site says D & E will operate on the "same" headways, and says that's "approximately every 5 minutes", but the D & E today operate on 7min and 6min headways.

If there were a "U" shuttle running every 5 minutes, and an E going to Tufts every 5 minutes, where would you turn the D?
 
Maybe I'm being dense, but I honestly don't know:

How would a single-track shuttle between Union and Lechmere be any cheaper than a single-track branch between Union and Lechmere? Especially given that the flyovers are already being constructed and Lechmere will be relocated either way.
 
^I should have been clearer: the "U" would be a rail shuttle to Lechmere (I gave it a letter in the hopes it'd be clear I wasn't saying "bus"). Arup implies that single-track GLX alongside the Fitchburg Line would save a lot of $.
 
Arlington said:
^I should have been clearer: the "U" would be a rail shuttle to Lechmere (I gave it a letter in the hopes it'd be clear I wasn't saying "bus"). Arup implies that single-track GLX alongside the Fitchburg Line would save a lot of $.
Click to expand...

Do you know how it would "would save a lot of $?"
 
bigeman312 said:
Do you know how it would "would save a lot of $?"
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I'm just riffing on page 18
Union Square Branch
• 3,600 Boardings Daily
• Only 144 for Lechmere Station
• GLX Washington: ½ mile
The Union Square Branch is currently ~ 15% of Construction Cost
• Commuter Rail Station with service to
North Station
• Eliminate Light Rail Transit tracks
and associated works
• Do not relocate commuter rail track
• Shuttle to/from Lechmere
• Bus
• Single track Light Rail Transit
Click to expand...

And the question of how many of the station-simplification things they'd do, particularly given USq being built as a stub (but designed for through-to-Porter)
 
That answers the question as to why a single-track would be cheaper than a double-track, which is fairly intuitive. It still doesn't answer my question though:

How would a single-track shuttle between Union and Lechmere be any cheaper than a single-track branch between Union and Lechmere? Especially given that the flyovers are already being constructed and Lechmere will be relocated either way.
Click to expand...
 
I'll guess its operational--a shuttle is better value-for-money.

If the "Real D" came out on a single track, it could get all jammed up during irregular ops or even killed by plain old bunching.

For a lot of branch scenarios (I saw them for both Dulles and Oakland airports, for example) having a shuttle to ping-pong back and forth from "the mainline" to the branch's terminus (USq in this case, but IAD on WMATA Silver and OAK on BART) can provide "full headway" service (at the cost of a vehicle change) that outperforms branching the mainline. (at the airports was on much lighter vehicles too)

If the "Real D" were only coming to USq every 7 minutes, a single track shuttle op, running every 5 to meet the Real E (also running every 5) might provide superior service (and be a better way of getting to Tufts than an D every 7 and an E every 6)
 
^That makes sense. I guess a single-track branch wouldn't be feasible because of unpredictability of when the train will pass Lechmere.

ADDITION: If a single-track shuttle would substantially cut down on costs, I would support that build.
 
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