Passenger Trains > AMTK catenary height in DE and MD

I've asked this Q before on Eastern board, with no definitive answers. What is AMTK's catenary height above top of rail (ATR) on the NEC between Ragan, DE (Newport) and Perryville, MD? And, what is the clearance between the top of a freight car and catenary needed to avoid arcing ( like a lightning bold)? My recent observation at Ragan is that it is a foot, or less, above the roof of an enclosed auto rack car (which is 19'0 ATR). Thank you in advance.

Most autoracks are between 19'5" and 20'2"!

Mike

I think I read in one of you're original posting that Amtrak requires a minimum clearance of 4". I may be wrong. If you're wondering about arcing think about this. The spark plugs in your car have gaps measured in the thousandths of an inch. Typical voltage to jump the gap is between 12,000 and 25,000 volts, about the same as the voltages on the NEC. That's overkill for spark plugs but I'm sure it's done to prevent missing. You can look at Paschen's Law for a better description of what is required to bridge the gap. Once the gap is bridged, the gap can be expanded quite a bit before the arc can no longer be maintained. Pachen's Law gets rather deep but I think it takes 3 million volts to arc a gap of 1 meter. A gap of 4 inches is about 0.1 meter. That would require 1/10 of 3 million volts, or about 300,000 volts. A 4 inch gap doesn't allow for bounce, of something loose on top of a car, or just about anything else that could happen.

John

Just read thru a journal which specifies height of wire above top of rail for doublestack clearance, in north america
is generally 21' 4"

2720 Wrote:
-------------------------------------------------------
> Most autoracks are between 19'5" and 20'2"!
>
> Mike

AAR Plate K requires them to be 20' 2" or less. Same 20' 2" max height is also true of double stacks which have to adhere to Plate H.

To John, thanks for your explanation. The 4" clearance I mentioned is the bounce margin for 20'2" stacks in tunnels or under bridges in non-electrified territory. I do not know the proper arcing distance; trying to find out. I just watched a 9000 foot 36A pass Ragan, including 73 multilevels, five of them articulated with a mark I have not seen before, TOAX. Right there the clearance from the top of the auto rack roofs to the wire looked to be about the same height as the roof itself. Standard enclosed auto racks, TTGX or ETTX, are 18'10 to 19'0 max according to my recent Equipment Register. As mentioned above the Auto-Max cars liked by Honda are 20'2 and do not come here. I'm sure if they could, they would, because the Wilmington auto facility on NS is Honda's, used for exporting Honda products built in the USA.

Double stacks at 20'2 do go under SEPTA's ex-RDG catenary from CP-Wood to West Trenton, about six miles.

I have read elsewhere from a usually reliable source that the highest catenary height on the NEC is 23' and the lowest is around 15' 4". The highest equipment allowed in the most constrained parts of the NEC is 14' 6" tall. In those sections one is not allowed to lower or raise pantographs while the catenary is powered.

Jishnu Wrote:
-------------------------------------------------------
> I have read elsewhere from a usually reliable
> source that the highest catenary height on the NEC
> is 23' and the lowest is around 15' 4". The
> highest equipment allowed in the most constrained
> parts of the NEC is 14' 6" tall. In those sections
> one is not allowed to lower or raise pantographs
> while the catenary is powered.

I've been told that's one reason the Keystone service AEM-7 units don't change their pantograph as they change directions inside 30th street station. In a variation on usual practice, the lead pan remains up on the eastward trip between Philadelphia and New York.

Wire heights in the NEC go from 24' at the engine pits to 15' 1" in the North River Tunnels. Standard wire height on the open road is 21' on the PRR side and 20' 6" in New England. This of course varies under bridges. The routes with tri level auto racks have wire 20' or better. Amtrak limits tri levels to 19' only and does not currently permit double stacks. Vehicles allowed to go to New York Penn Station cannot exceed 14' 8", Newark, Philadelphia and Baltimore it s 15' 6" (plate C).

The clearance is a sliding scale depending on the lengths of the spans. Attached wire under bridges or in the tunnels it is 5", on open track with 300' spans it is 9", double that for open top loads.

Ah! That explains the 14' 8" height of the standard single level car specification. Although there is that minor issue of entering and exiting the North River tunnels from/to diverging tracks at Penn Station, which caused the NJT MLVs to have beveled roof line, and which restricts the LIRR C3's from venturing south/east of Penn Station through the North River tunnels.