• SEHSR Southeast High Speed Rail Corridor

  • General discussion of passenger rail proposals and systems not otherwise covered in the specific forums in this category, including high speed rail.
General discussion of passenger rail proposals and systems not otherwise covered in the specific forums in this category, including high speed rail.

Moderators: mtuandrew, gprimr1

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  by RRspatch
 
David Benton wrote: Sat Sep 19, 2020 10:43 pm Is the tunnel single or double track?
The 1st street tunnel consists of two single track tunnels. Back in the 90's both tunnels had the track lowered about as far as they could (without the walls coming in) so that they clear Amtrak Superliners and VRE Gallery cars. As far as I know there is no room for catenary wires or catenary rails. Digging new tunnels in Washington is problematic due to Metro subway tunnels, the Congressional subway system and important government buildings. I'm not sure if the Senate subway goes over or under the 1st street tunnel.
  by David Benton
 
Whilst the metro might still be a problem, they appear to have made a lot of progress in grout technology etc in the last decade or so. Tunnels here that were considered unlowable are been lowered.
  by electricron
 
David Benton wrote: Sun Sep 20, 2020 3:05 am Whilst the metro might still be a problem, they appear to have made a lot of progress in grout technology etc in the last decade or so. Tunnels here that were considered unlowable are been lowered.
Where is here?
The First Avenue Tunnel is really two single track passenger only tubes (cut and cover) southern entry/exit to D.C.s lower level Union Station. The present tunnel height is 17 feet after lowering the track bed in the 1990s, about 20-30 years ago. It was lowered so VRE double level commuter coaches, Budd style "Galley Cars", could access Union Station. These tunnels opened in 1908 with Union Station.
The Virginia Avenue Tunnel was a double track tunnel built in 1872 servicing both passenger and freight trains under D.C. that was freight only upon opening of the First Street tunnel in 1908, and was single tracked when electrified in 1936. It's present height is 18 feet. It is in the process of being replaced by two new single track tunnels 21 feet tall for double stack containers and autoracks.. The first new tunnel was opened December 2016. I am not aware of the status of the second new tunnel. All these tunnels were built using the cut and cover method in/on loose soils. Not bad for a tunnel built in 1872, almost a 150 years ago.
How many times do you think engineers can safely lower track beds in tunnels?
  by mtuandrew
 
CSX Virginia Ave Tunnel is complete and sees double-stacks daily.

First Street Tunnel runs directly over WMATA Capitol South Station, between (and under one of the) House office buildings, between the Capitol and the Library of Congress & Supreme Court, between the Senate office buildings, and under(?) the entire set of Congressional tunnels linking all the buildings I mentioned. I have no idea what other utilities surround it, but there have to be lots of electric, gas, water, steam (yes the Capitol complex has steam heat) and sewer pipes around. Can’t just take a shovel to it.

Best bet is to use panel track to reduce the needed height (in lieu of track on ties on ballast), but beyond that... there isn’t much Amtrak can do without getting into the hundreds of millions per inch of clearance.

EDIT: and yes, it’s two single-track tunnels. I don’t know whether or how they’re interconnected.
  by Literalman
 
Wikipedia says it's a two-track tunnel but has a photo showing two portals. Wikipedia also links to a 1903 New York Times story calling it a twin tunnel. I've ridden through it many times and thought it was two single-track tunnels. Maybe it's a two-track tunnel but with separate, connected single-track tubes?
  by MattW
 
How possible would it be to tie electrification into PTC so when a Superliner/VRE train goes through the tunnel, the wire is de-energized?
  by electricron
 
MattW wrote: Sun Sep 20, 2020 5:08 pm How possible would it be to tie electrification into PTC so when a Superliner/VRE train goes through the tunnel, the wire is de-energized?
The power on the overhead catenary in DC is 12,000 volts at 25 Hz. Have you ever seen a 12,000 volts circuit breaker, and what its’ mechanical life/duty cycle is?
http://eaton.org.cn/ecm/groups/public/@ ... 130881.pdf . Yes, 2500 cycles is their mechanical life/duty cycle. Let’s do the math; twice and hour, 16 hours a day, 32 cycles per day. 2500 cycles/32 cycles/day = 78 days. That is less than 3 months.
If twice an hour is too many, once an hour would double that time to 156 days, that slightly more than 5 months. Switching 12 kV on and off is not done as often as you suggest, it is usually more like once a week or month in practice, de-energizing the medium voltage circuit for maintenance.
  by mtuandrew
 
More practical in this case to have a 5-mile-range battery backup in whatever motive power they get for a hypothetical future electrified SEHSR. That gets you well out of any of the NEC tunnels without issues, without needing an entire carful of batteries as you would for a BMU commuter unit, and without eating circuit breakers for breakfast.
  by electricron
 
mtuandrew wrote: Sun Sep 20, 2020 8:20 pm More practical in this case to have a 5-mile-range battery backup in whatever motive power they get for a hypothetical future electrified SEHSR. That gets you well out of any of the NEC tunnels without issues, without needing an entire carful of batteries as you would for a BMU commuter unit, and without eating circuit breakers for breakfast.
A better choice by far. Another possibility is a small diesel generator set on the train to power the electric motors for the short distance into Union Station. Either option would work.
  by David Benton
 
You wouldn't use a circuit breaker to switch the circuit in and out , this frequently. You would use special switching machinery , which senses when the phase is at zero volts , and switches out then. a lot less wear and tear.
Regardsless , the battery solution is still better , and handy for yard work etc as well.
  by orulz
 
Saying "no wire through 1st street" is, to me, the tail wagging the dog. Bad policy. It allows VRE to use antiquated rolling stock which is fine for now but should not be considered non-negotiable in the future.

How about:
1. If you're electrifying south of WAS there is literally no excuse for VRE to keep running the stupid gallery cars. Scrap them and get some modern EMUs that would fit under wire.

Plenty of bilevel designs exist that would fit. Stadler KISS is 15' tall, for example, which is 10" shorter than the gallery cars, leaving 2' of space overhead which should be plenty of clearance for wire. KISS also can have level boarding at high *and* low platforms, which would be perfect for a VRE-MARC run-through train. The missing piece is an electro-diesel version which would allow operations without full electrification - but, whatevs! Just go ahead and electrify.

2. What superliner trains even run via 1st St? None, right? It doesn't even make sense because superliners can't run on the NEC anyway (BP tunnel, North River/NYP/etc). If they are trying to turn the Capitol Limited, which doesn't run on the NEC, into a through train, to NPN or NFK or some such, without changing its equipment, then just forget it because, again, tail wagging the dog. If there ever is a non-stupid reason to run taller trains onto the NEC (which I can't fathom, but anyway...) then run them via Virginia Avenue and stop at ALX instead of WAS.
  by gokeefe
 
Wire or not in the First Street tunnel simply is not a serious issue on my opinion. There are too many other viable options around it to consider it a show stopper. Third rail could be a possibility. Also dual mode (diesel - AC electric). Obviously third rail would imply dual mode power as well (diesel - DC electric). Seems a lot more sensible to go with dual mode for AC electric which would allow service to "stretch" to terminals on corridors which will never have overhead wires (Roanoke, Bristol etc.). This type of motive power would also have some significant benefits to other parts of the NEC.

Sent from my Pixel 2 XL using Tapatalk

  by MattW
 
electricron wrote: Sun Sep 20, 2020 7:15 pm
MattW wrote: Sun Sep 20, 2020 5:08 pm How possible would it be to tie electrification into PTC so when a Superliner/VRE train goes through the tunnel, the wire is de-energized?
The power on the overhead catenary in DC is 12,000 volts at 25 Hz. Have you ever seen a 12,000 volts circuit breaker, and what its’ mechanical life/duty cycle is?
http://eaton.org.cn/ecm/groups/public/@ ... 130881.pdf . Yes, 2500 cycles is their mechanical life/duty cycle. Let’s do the math; twice and hour, 16 hours a day, 32 cycles per day. 2500 cycles/32 cycles/day = 78 days. That is less than 3 months.
If twice an hour is too many, once an hour would double that time to 156 days, that slightly more than 5 months. Switching 12 kV on and off is not done as often as you suggest, it is usually more like once a week or month in practice, de-energizing the medium voltage circuit for maintenance.
So don't switch at 12kV, step it down to 3kV or whatever, switch it, step it back up to 12kV. Sure it adds cost, but does the increased cost offset the ability to keep running bilevel equipment through, while also allowing electrification south? I don't know. Maybe another idea to reduce switch cycles is to use creative dispatching and run bilevels through one side, electrics through the other, and only switch a few times per day.
  by gokeefe
 
Circuit breakers don't seem like the right answer but gear similar to that used on the drawbridges ought to do the trick. When the two ends of the wire are open you could have a grounding wire on the isolated portion that would switch closed and fully safe the isolated wire in the tunnel.

This hardware already has the ability to be interlocked and would be PTC compatible.

It would be interesting to see which approach would save more money ... Dual mode engines or isolation gear for tunnel wires over high level cars ... I'm guessing isolation gear would be cheaper ... Perhaps by a lot ...

Sent from my Pixel 2 XL using Tapatalk

  by RRspatch
 
The only Superliner trains that run through the 1st street tunnel are the occasional runs of trains 952 and 953. These are equipment runs between Washington and Lorton for transfering locomotives and cars that need to go to Beech Grove via either the Capital Limited/Cardinal via Chicago or perhaps directly via the Cardinal.

Mattw above mentioned above about using a lower voltage in the 1st street tunnel. Half of 12.5 Kv is 6.25 Kv which would buy you more protection from flashover. The change over point would probably have to be somewhere north of New York Avenue (CP Avenue) to avoid the change over being near the 1st street tunnel. The change over from 6.25 Kv 25 Hz to say 25 Kv 60 Hz would be somewhere south of CP Virginia and Long Bridge. Having VRE ditch the Gallery cars (METRA or Music City could buy them) and go to Stadler Caltrain cars would allow an S Bahn/RER run through operation between the MARC Penn line and the VRE CSXT line.
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