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City Nolan

@ndhapple.bsky.social

14K followers 930 following 21K posts

Words in Streetsblog. Examining how we make passenger rail better (electric/modern) for NYU-Marron. Prev: NY Mag, NY Post-Metro, NYDN. Hook’em🤘. 🏳️‍🌈. Tips? [email protected]; Signal/WhatsApp.

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City Nolan @ndhapple.bsky.social · 6h

In fairness, these design decisions were made under Pataki, who made a big deal about downsizing and outsourcing functions at the MTA. Those decisions left the MTA entirely unable to police, edit and understand what it was getting back. Cuomo has many other MTA-related sins, but this is not one.

City Nolan @ndhapple.bsky.social · 6h

Yes

City Nolan @ndhapple.bsky.social · 6h

Makes sense. Would have been of that era

City Nolan @ndhapple.bsky.social · 6h

Anyways, if you're interested in station design (guilty) this is an excellent primer about what good structural station design decisions look like: Minimize digging, match station box length to platform length as much as possible, tuck in ancillaries. Build for the future, but not excess.

City Nolan @ndhapple.bsky.social · 6h

"The integration of ancillary spaces into the overall
design of the station can help simplify the basic shell form
and thereby materially reduce construction costs by reducing
the necessity to construct special structural shapes or to
*extend the station space beyond the platforms*"

PDF pg 77.

City Nolan @ndhapple.bsky.social · 6h

"[T]rain length determines the length of platform. Length is the first parameter affecting the scale of the station. The overall station length is finally determined after ancillary spaces are positioned according to site opportunities to *minimize* excavation volume."

PDF pg 57, emphasis mine

The excerpt from PDF pg 57 as quoted above, document pg 47

City Nolan @ndhapple.bsky.social · 6h

PDF Pg 166 details why depth matters. A station going from 20 feet to 10 feet deep reduces overall station costs by 15% (all other things equal), going from 20 feet to 30 feet increases overall station by 20%.

City Nolan @ndhapple.bsky.social · 6h

PDF pgs 167 and 168 dictate how the length and width of your platforms drives station design. This, of course, is predicated on your structural box being as tightly hewed to your platform size as possible.

City Nolan @ndhapple.bsky.social · 7h

Good question. I'd presume the parts built by De Leuw as they did the study.

City Nolan @ndhapple.bsky.social · 7h

It includes *seven* sample station designs. This is Model Station Design No. 5. You'll recognize this if you've ever taken the DC Metro or the subway in Montreal.

Note that the ancillary/back of house spaces are primarily tucked into the ends of the mezzanine level instead of extending the box.

Side cutaway of the No. 5 Model Station design. If you blow it up in the PDF, you can see the ancillary spaces are extremely small, located in the upper left and right corners of the station box.

Vertical level cutaways for Station Design No. 5. The backroom spaces are predominately on the mezzanine level instead of extending the station box.

City Nolan @ndhapple.bsky.social · 7h

Model station designs for both cut and cover and mined! It favors mined-twin tubed stations (a la Crossrail) because of reduced excavation size. The US/MTA habit of mining boxes underground is likely the most expensive way to build a subway station.

Pdf pgs 55 and 56.

Model cut and cover schematic

Model mined twin-tubed subway station

City Nolan @ndhapple.bsky.social · 7h

Station cost principles, pg20:
- Very shallow cut-cover is the cheapest
- Station cost drivers is excavation/site 40%; structural items 35%; 25% systems and finishes;
- Cost is "very dependent on volume for mined stations, and station volume and depth of excavation for open-cut stations"

City Nolan @ndhapple.bsky.social · 7h

Principle 8: Assume water will get in. "Station finish ...materials which stand free from the structure permit control of groundwater seepage and accommodate generous construction tolerances."

Think about how many after-action audits on projects have been knocked on these merits!

City Nolan @ndhapple.bsky.social · 7h

Principle 7: "Architectural with construction economy can be achieved by utilizing a relatively compact and simple station shape; modest dimensions for length, width and height; minimum depth of cover; repetitive structural formwork or structural shapes; and repetitive finish elements."

City Nolan @ndhapple.bsky.social · 7h

Principle 4: Cut-cover stations are almost always cheaper unless you're going deep. Keep these as shallow as possible. If you're mining, make sure the dig is as small as possible.
Principle 5: Mining is almost always more expensive unless you're having to go deep or are in a dense urban setting

City Nolan @ndhapple.bsky.social · 7h

Breaking this out:
- Design principle #2: "Decisions on station characteristics made early in the planning and design phases offer the most significant opportunities to control costs"
"These decisions include the determination of station location, volume and depth of excavation."

"Decisions on station characteristics made early in
the planning and design phases offer the most
significant opportunities to control costs of
underground stations. These decisions include the
determination of station location, volume and
depth of excavation."

4. For open cut or cut-and-cover stations, depth of
excavation should be minimized. For mined stations, the volume of excavation should be minimized to reduce costs. For both types of construction, station width and length should be established
realizing their ultimate impact on station cost.
5. Earth mined excavation is almost always more
costly than open cut or cut-and-cover at normal
depths. However, mining in competent rock can be
competitive with open cut The option to use mined excavation in an urban environment is vital to develop more acceptable solutions
to the problems of locating underground stations
in intensely developed areas."

City Nolan @ndhapple.bsky.social · 7h

Here are the Subway/Metro Station design guidelines that were compiled by UMTA/USDOT in the 1970s in an attempt to prevent WMATA-style cost overruns again.

It got shelved when everyone at UMTA got laid off and we forgot it. But it's prescient about cost drivers -- rosap.ntl.bts.gov/view/dot/11352

ROSA P serves as an archival repository of USDOT-published products including scientific findings, journal articles, guidelines, recommendations, or other information authored or co-authored by USDOT ...

rosap.ntl.bts.gov

City Nolan @ndhapple.bsky.social · 7h

Here are the Subway/Metro Station design guidelines that were compiled by UMTA/USDOT in the 1970s in an attempt to prevent WMATA-style cost overruns again.

It got shelved when everyone at UMTA got laid off and we forgot it. But it's prescient about cost drivers -- rosap.ntl.bts.gov/view/dot/11352

ROSA P serves as an archival repository of USDOT-published products including scientific findings, journal articles, guidelines, recommendations, or other information authored or co-authored by USDOT ...

rosap.ntl.bts.gov

City Nolan @ndhapple.bsky.social · 7h

Agreed. In addition to that, FTA/FRA never really re-established R&D (e.g. Metroliner or the NG Metro train experiment). Nor did they set up any kind of guidance on service driving design, or comparative design, so... you end up with everyone stapling together 60-year old wish lists.

City Nolan @ndhapple.bsky.social · 7h

Re: the discourse about the Seattle Link station:

Going under a tunnel is going to be painful, but there's a lot of stuff separate from the tunnel depth that should be looked at. The deeper you go, the worse the station costs get and it happens in almost an exponential fashion.

City Nolan @ndhapple.bsky.social · 10h

Two things immediately jump out separate from the tunnel depth.

First, the depth of the station box, what’s going on those two bottom levels? Passengers won’t be using them, they’ll be following the passageway.

Second, 34’ wide platform seems way excessive. (SAS was 28’)

Scribbled schematic for SOUND station

City Nolan @ndhapple.bsky.social · 7h

Jeez jeez jeez

City Nolan @ndhapple.bsky.social · 7h

Yikes

City Nolan @ndhapple.bsky.social · 7h

And the total gutting of the planning and research muscle. FRA saw like 80% of its staff get RIFd, UMTA too. It's been a very expensive 30-40 year lesson that knowledge is hard, forgetting is easy and doing so is very expensive. (And I think I'd argue we're still short of where we were.)

City Nolan @ndhapple.bsky.social · 7h

^or^ cut it back, not and. Note to self, don't skeet about trains whilst listening to baseball.

City Nolan @ndhapple.bsky.social · 8h

It has lovey bite.