Transbay Terminal Rail alignment development
TTT environs drawn in Illustrator (v9,
displayable as PDF),
the CAD tool of dilettantes
(Illustrator 8 version)
(background orthophoto
image in Photoshop format)
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Overview
of terminal geometrical constraints
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Overview
of entire extension alignments (1.9mb PDF)
(background image)
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Handout
briefly summarizing some of the trade-offs of accepting
different constraints in track and platform geometry
and suggesting some desiderata for any downtown San
Francisco railway station.
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Oblique orientation (aka "Richard Preferred
Alternative" -- in February 2001, but subsequently
considerably refined).
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Through platforms 360m, 360m, 370m, 370m, 330m;
Stub platforms: 310m, 310m.
Nearly straight platforms.
Western approach from Second Street, eastern under Mission.
180m minimum radius. 500m/800m platform
curvatures.
Requires purchase of 301 Mission (3719-1, 3719-17).
Baywards continuation under Mission Street,
under Muni Metro Turnback and into the Bay.
Fantasyland!
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As above, but with four stubs: 300m, 270m, 260m, 240m.
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As above, but with no stubs. Through 360m, 360m, 370m,
380m, 380m.
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Western approach from Essex Street,
eastern under Mission. 180m minimum radius. 500m/800m
platform curvatures.
Through platforms 290m, 290m, 310m, 310m, 310m.
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As above (Essex/Mission) but with 150m curves.
Through platforms 290m, 290m, 310m, 300m, 310m.
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As above (Essex/Mission 150m) but with a sixth, terminating.
road at the cost of extra private easements.
Through platforms 290m, 290m, 310m, 300m, 310m, 310m.
- Just for reference. 301 Mission avoided, but at large
cost. Straight (or nearly so: 800m radius) stub
platforms. 180m minimum radius.
Stub platforms: 280m, 280m (possibly through), 320m,
320m, 310m.
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Platforms built on a 500m curve, minimum radius
180m (ie UIC compliant!). Second Street.
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What happens when mimimum radius is increased to 200m, and
when platforms are not allowed to be curved. For edification
only, as the trade-offs make these poor contenders.
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200m min radius,
500m platform radius.
5 through platforms:
280m, 300m, 300m, 270m, 270m
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200m min radius,
straight platforms.
4 through platforms: 180m, 180m, 200m, 200m.
Two terminating: 250m, 230m
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200m min radius,
straight platforms.
5 through platforms: 180m, 180m, 180m, 190m, 190m
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Much older concepts with 150m minimum radius.
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Platforms built on a 500m curve, trading CCTV monitoring of
invisible train doors for longer platforms and smaller
takings.
Western approach from Second Street, eastern from Main.
150m minimum radius. Only 100m or so of straight platform.
- As above, but curved at the western end only; losing 30m of
overall platform length in order to have 150m of straight platform.
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Straight platforms. Western approach from Second Street,
eastern from Main. 150m minimum radius.
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Straight platforms. Western approach from Essex Street,
eastern from Main. 150m minimum radius.
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PTG Madness.
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150m curvature, straight platforms, approaches from
Second and Main streets.
This is the basis for
"Option 2"
in the TTT EIR NOP.
Yes, this is seriously what they've drawn up and are
proposing. Imagine trying to actually operate trains
in and out of this! Conflict-o-rama!
Stubs 320m, 260m, 260m,
290m. Through 290m, 290m
Note that these aren't the actual Super Secret
Engineering Drawings: they're my reconstructions, but are
very close to the original.
Extended
Dance Remix showing throat nuttiness extending
unusable triple trackage to Bryant Street.
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Ugh!
This is the basis for
"Option 1"
in the TTT EIR NOP.
The reality is actually far, far, far worse than I
imagined here. What I've drawn (with its masses of
approach special work and resulting availablility of
three simultaneous approach paths to most possible
platform combinations) might actually be operable, the
real PTG Madness is absolutely untenable.
Of course, this is all academic, since there is no way
to construct this mess, given the depth of the tracks
(under a mandatory mezzanine, circa 30 feet below sea
level) and the height of the terrain (over 80 feet above
sea level where the junction would be located), all
combined with poor rock (entered around Folsom Street) and
the overlying bus ramp and Fremont Street bridge ramp.
Extended
Dance Remix showing nutty junction and putative transbay
alignment.
A scan of a
memo from the sleaze-ridden
California High Speed
Rail Authority
about minimal turning radii for high speed equipment. 1.4mb of
PDF-formatted 300dpi scanitude.
Richard Mlynarik
Last modified: Sun May 2 01:37:25 PDT 2004