Resources for finding bridge clearances?

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Resources for finding bridge clearances?

Postby BostonUrbEx » Fri Apr 03, 2015 2:10 am

Anyone know where to find a map, list, data sheet, anything at all about rail clearances, particularly for bridges? For example, how would you find out which bridges would need to be raised on the Lowell Line to allow for autoracks with catenary wire? (Just as an example)

I can't find any info at all. Best I have is a PAR clearance map which doesn't show specifics. Just generalizations for entire lines.
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Re: Resources for finding bridge clearances?

Postby F-line to Dudley via Park » Fri Apr 03, 2015 3:42 pm

BostonUrbEx wrote:Anyone know where to find a map, list, data sheet, anything at all about rail clearances, particularly for bridges? For example, how would you find out which bridges would need to be raised on the Lowell Line to allow for autoracks with catenary wire? (Just as an example)

I can't find any info at all. Best I have is a PAR clearance map which doesn't show specifics. Just generalizations for entire lines.


http://uglybridges.com/

Sourced from NBI bridge info. Important caveats that make it at-best a partial solution, however:

-- Under-clearances are not necessarily at centerline of the tracks, which is the only clearance that matters for trains. Some of them could be at the bridge's centerline instead of track centerline, and some of them could be totally non-centerline. You have no way of knowing without a RR survey. So many of these are not going to correspond at all to the actual CSX or PAR clearance data.
-- Some are way out-of-date. The recently-raised B&A bridges and recently-dropped B&A trackbeds for the CSX double-stack project aren't updated at all here. And even if they were, because it doesn't correspond to track centerline many of them wouldn't reflect the current 20'6" clearances even if they were up-to-date.

At best, it's useful for checking off bridges on the list that do amply exceed a given clearance. And for maybe making some ballpark conjectures. The various New England state rail plans are really lousy at their bridge inventories for freight clearances. New Hampshire's does list the Western Route bridge clearances that would have to be squared for PAR double-stack (it's surprisingly few) and CDOT has some documents for what needs fixing on NECR to bring the 19'6" upgrades from their current end at Willimantic down to end-of-the-line at New London docks. But those are the only ones.



Lowell's currently cleared for 17' and the double-deck autoracks that PAR used to bring out of Boston Autoport. And we know that the PAR main has long-term plans to extend 20'6" DS from Ayer to Portland after the PAS project is done, so that lumps in all overlap with the Fitchburg, Lowell, and Haverhill Lines.


As for electrification, the agreed-upon worldwide standard used abroad and adopted here (with Amtrak blessing) for CAHSR, Caltrain, and GO Transit's electrification is +2'7" additional over the current minimum undergrade clearance for diesel for installations of a 25 kV line. (See the ongoing Amtrak thread.) That achieves adequate electrical separation between both wire vs. bridge underside and wire vs. the unshielded roof of a tall freight car. So, with that in mind (pasted from the AMTK thread). . .

Per CSX's clearance system map:
-- 17' for Plate F
-- 18'6" for international-cube double stack
-- 19'1" for tri-level autoracks
-- 19'6" for mixed DS (stack of 1 international + 1 domestic cube)
-- 20'2" for full-domestic DS

Usually autoracks + mixed cubes get grouped together because there's enough in the trackbed bag of tricks to easily make up that 5-inch difference, so any autorack route goes straight for 19'6". Very few lines hit that 18'6" mark because it just doesn't enable enough above-and-beyond. For full domestic DS generally a little padding over 20'2" is preferable, so CSX et all shot for 20'6" on new-clearance projects like the B&A. The max possible that any railroad maintains is 22', but that's rarely if ever needed because of the low-riding DS well cars that save a little space. Only a few western and Canadian lines have the Class I's holding out for 22' ransom, with east-of-Mississippi routes in CSX and Norfolk Southern territory topping out at 20'6" max.

So...adding 60 Hz, 25 kV wires:

-- 17' + 2'7" = 19'7" (Plate F)
-- 19'6" + 2'7" = 22'1" (tri-level autorack)
-- 20'2" + 2'7" = 22'9" (minimum DS)
-- 20'6" + 2'7" = 23'1" (preferred DS)
-- 22'" + 2'7" = 24'7" (theoretical max, n/a east of Chicago)
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Re: Resources for finding bridge clearances?

Postby GP40MC1118 » Fri Apr 03, 2015 6:20 pm

Height restrictions are found in the railroad's employee timetables.

The New Hampshire Route mainline has some restrictions at the south end:
Somerville:
School St restricted to Plate E No.1 Track only
Walnut St restricted to Plate E No.1 Track only
Cross St restricted to Plate E BOTH tracks.

D
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Re: Resources for finding bridge clearances?

Postby BostonUrbEx » Fri Apr 03, 2015 11:12 pm

GP40MC1118 wrote:Height restrictions are found in the railroad's employee timetables.

The New Hampshire Route mainline has some restrictions at the south end:
Somerville:
School St restricted to Plate E No.1 Track only
Walnut St restricted to Plate E No.1 Track only
Cross St restricted to Plate E BOTH tracks.

D


So the high-wide crossover between the No.2 and the Yard 8 Lead is the only thing allowing plate F cars into Boston? And GLX will further restrict that?
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Re: Resources for finding bridge clearances?

Postby F-line to Dudley via Park » Sat Apr 04, 2015 2:45 pm

BostonUrbEx wrote:
GP40MC1118 wrote:Height restrictions are found in the railroad's employee timetables.

The New Hampshire Route mainline has some restrictions at the south end:
Somerville:
School St restricted to Plate E No.1 Track only
Walnut St restricted to Plate E No.1 Track only
Cross St restricted to Plate E BOTH tracks.

D


So the high-wide crossover between the No.2 and the Yard 8 Lead is the only thing allowing plate F cars into Boston? And GLX will further restrict that?


The bridges aren't necessarily a problem if the trackbed is lowered in the retaining wall construction. Everything's going to shift around due to retaining wall construction, so the current footprint is not going to be static. That is, however, a a fine-print detail you're not going to find in any GLX project docs. Some project manager or some inside source would have to confirm what the deal is with that, but there are no technical barriers at any of these locations to squaring 17' clearances at the trackbed level.

Cross St. overpass is being reconstructed right now with new decking. I can't tell all that well from Google Street View, but the new deck appears to have a less-pronounced 'hump' in the middle and is taller on the edges. Either way, that's another one where level of the trackbed may change with all the retaining wall construction.


The fatal blocker is still the carhouse ramps wrecking the around-the-horn access to BET. Plate F matters not one whit if they don't have storage, and if Cobble Hill is the only means of getting around. Keep in mind, though, because of the Leverett Connector ramps, Mystic Ave., and 99/16 interchange ramps you couldn't get Plate F's to/from Everett Terminal even if you wanted to. You can also never get anything taller than double-decker autoracks to/from the Autoport, and PAS is not interested in that because they transport nothing but tri-levels at Ayer and from the P&W interchange in Gardner. It'd be an unforgivable gaffe if GLX wrecked the wide clearances that are indeed a going concern, but tall really isn't much of a business consideration for Boston-proper.
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Re: Resources for finding bridge clearances?

Postby GP40MC1118 » Sat Apr 04, 2015 4:28 pm

It will all be a moot point this summer when Yard 8 is closed forever.
DOBO and LA-2 (when it comes to Somerville) will run via Reading, as there
are no current plans to do the Cobblehill connection. GLXcess rules.

As it was pointed out recently, GLXcess gets what they want and that's that.

D

PS - In answer to the Plate F question - Yes, they can only operate down No.2 Track
to Walnut Street crossover into Yard 8.
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