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.
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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-- Some are way out-of-date.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)
