Amtrak Gateway Tunnels

I strongly suspect that the encasement of the 12kV conductors in a concrete raceway/conduit is to minimize the chance of mechanical damage from any potential cause, especially when trackwork, etc. is being performed. Additionally, the encasement provides mechanical support which lessens the potential wear from vibrations and greatly simplifies the task of replacing a failed cable. My employer from which I am retired has underground transmission at Voltages up to 345kV and most if not all of which is encased.

I will add a little to the speculation about the cables, but I warn you that I am not involved in the design and probably I am not aware of all the considerations that go into it. The Channel Tunnel has its cables racked on the wall without encasement. I have not tried to look up the voltage, but presumably it is 25kV or more as that it the standard catenary in Europe. The concrete bench in the existing Hudson tunnels is needed for evacuation. I suspect that it is against the egress requirements to have 25kV cables subject to damage hanged over the egress walkway as in case of emergency unsuspecting passengers evacuating a train would come in contact with the cables and then the only thing between them and certain death is the cable insulation which will be hard to warrant to be damage free after years of use and abuse. When the cables are encased in the concrete bench or metal pipes damaged insulation is much more likely to cause a short to the metal pipes and trip the power breakers as the path to ground (or water in case of the tunnels) is much better. Note that this issue is not present in the Channel tunnel as the evacuation route is a third smaller service tunnel in between the two train carrying tubes. I believe there is no high power voltages present in that service tunnel.

Could not find a reference. However to be in sync with the rest of the PRR NEC suspect that the cables are in pairs essentially 69 Kv + and 69 Kv- . Also a neutral cable. That gives the 138 Kv potential between the two power cables. Remember those cables can supply power in either direction from Sunnyside to Newark Penn station and south. That is for redundant power supplied from 2 or more sources.

In case of an evacuation you do not want even the slightest possibility of a passenger touching the cable and the cable having a bad piece of insulation. That can be a shocking experience.

east point wrote: ↑Wed Mar 11, 2020 9:15 pm Could not find a reference. However to be in sync with the rest of the PRR NEC suspect that the cables are in pairs essentially 69 Kv + and 69 Kv- . Also a neutral cable. That gives the 138 Kv potential between the two power cables. Remember those cables can supply power in either direction from Sunnyside to Newark Penn station and south. That is for redundant power supplied from 2 or more sources.

In case of an evacuation you do not want even the slightest possibility of a passenger touching the cable and the cable having a bad piece of insulation. That can be a shocking experience.

No neutral necessary, it's a two wire system. I can't think of a HV single power distribution system that uses a neutral wire. From what I gather, the multiple 12kV cables to the tunnel supply the equivalent power as the two 69kV feeders found above most of the RoW and on places like over the former Atglen & Susquehanna (Enola Low Grade Line) that's still integral to the distribution network.

I imagine they felt they could not properly insulate and contain 69 kV cables in a tunnel, so they stepped it down to 12 kV and ran multiple cables. This way if there's a power plant/converter failure in NY or NJ, they can still stream power from one side of the tunnel to the other.

WhartonAndNorthern wrote: ↑Wed Mar 11, 2020 9:43 pm I imagine they felt they could not properly insulate and contain 69 kV cables in a tunnel, so they stepped it down to 12 kV and ran multiple cables. This way if there's a power plant/converter failure in NY or NJ, they can still stream power from one side of the tunnel to the other.

138kV transmission underground pipe-type cable is typically an 8 inch diameter pipe. That utilizes three conductors, three phases, more space needed than Amtrak's 2 conductor single phase transmission. Not a problem to fit in the tunnel. 138kV pipe-type cable has been used by electric utilities over 60 years.

I would have thought the 12 K.V cables are feed cables for the nominally 11 K.V cat cable. The track is your Neutral return path , which would be tied to Earth. As would anything else metallic or capable of conducting electricity to eliminate induced voltages. There may be "neutral" cables , simply to reduce currents flowing through any earth cables and the earth itself. In some very simple systems, the neutral return is through the earth , but i doubt that would be the case with the amperage's involved here. (Kens example is a 3 phase system , where the loads are balanced between the 3 phases, where the return is balanced through the other phases -120 degrees of a rotating generator).
As someone said , it is an age old system that relies on everything having a good earth, so any leakage is high amperage, tripping the supply circuit breakers quickly. It predates double insulated tools etc, and earth leakage detectors, and is still the basis of most electricity supply systems. Nothing wrong with it , but the cables would have a metal sheathing or pipe , that would be tied (bonded)to earth. Hence my question, of why the concrete , which has been answered, thanks
Note: With a reread , I see Ken Mentions he is talking about a 3 phase system , seems i mixed a couple of post together.

Amtrk CAT system is single phase not 3 phase. However there are 3 phase feeders as well for sump pumps and other items. Forget if the 4400 v signal system is 3 phase or single phase ? Also there are phone system cables. Also the 600 V and neutral return for the 3rd rail system cables. There may be others ? For redundancy these are repeated in each bores. If one bore is shut down that redundancy may be lost ?

I'm all for more efficient repair methods. And I know in NY we tend to do things at a massively complicated and labor intensive way that drives up costs. But one of the criticisms of the L train approach was that it was band-aiding the issue - patching compromised concrete instead of properly repairing it.

For anyone whose seen the conditions of the tunnels, they're in really bad shape in places. And considering the amount of volume they handle, I would think a complete rip out is in order. They might need some more intense patching up to survive another decade, but I think they deserve a proper ground-up rehabilitation.

Both of the North(Hudson)tubes have turned into patches on top of patches by now,some of the East river tubes are not that far behind
after Sandy passed thru.
Gateway will allow the complete rehab of the 2 original tubes,THAT IS REALY NEEDED!!!
The L line tunnel was completely flooded and there're patches on top of patches as well,MTA had the right idea to strip out all of the old gear and replace with new,undamaged gear.
But the local NIMBYS objected to giving up "their"parking spaces to the bus bridge,and modified traffic flow. then Cuomo stuck his nose in
and stopped the project dead to placate the locals,and stuck his nose into the tubes to shame Amtrak in to action,which is not
possible,due to the current occupant of the White House.

IT is high time to get these projects going,before a total collapse effects the entire NY metro area,then the entire Northeast!!!!!
Let MTA handle the l line tunnel
GET PANYNJ to build portal,sawmill bridges and the gateway tunnels,ASAP

Given that the entire state of NY is now prohibiting employers from having more than 50% of their workers in any single office for the next 14 days, you're going to be witnessing what may be the beginning of the end of commuting for tens of thousands of workers.

The next two weeks will prove to major employers who resisted work from home that "business as usual" can indeed happen with remote workers.

eolesen wrote: ↑Thu Mar 19, 2020 4:37 am Given that the entire state of NY is now prohibiting employers from having more than 50% of their workers in any single office for the next 14 days, you're going to be witnessing what may be the beginning of the end of commuting for tens of thousands of workers.

The next two weeks will prove to major employers who resisted work from home that "business as usual" can indeed happen with remote workers.

Boston has already found out. They've added back some service to a few bus and trolley routes.

David Benton wrote: ↑Thu Mar 12, 2020 12:40 am I would have thought the 12 K.V cables are feed cables for the nominally 11 K.V cat cable. The track is your Neutral return path , which would be tied to Earth. As

Actually the CAT voltage is now nominal 12.0 Kv +/- 10 % Has been since the 1980s. System is single phase with 2 feeders one 180 degrees phase of other much like the 120 / 240 service to your home. Note the 120 figure is different at various places in the USA, here it runs at 127 / neutral / 127 V . What becomes bad is if the ground is not good enough you get a floating ground that may cause one leg to be higher than other. Have seen it be 100 / 154 . That is why some older homes can have electrical problems with lights burning out quickly, If you compare it to Amtrak's system the high voltage on one side would be disastrous .

Place your bets, everyone; "will it or won't it" (Gateway) be included within this proposed legislation:

https://www.nytimes.com/2020/01/29/us/p ... d=em-share

Fair Use:

…The 19-page plan to be proposed by Democrats includes $329 billion for investment in transportation systems, including improving safety measures for bicyclists and pedestrians, and $105 billion for transit agencies and maintenance needs. The framework also includes $55 billion in railway investments for both the expansion of the country’s passenger rail network and improvement of Amtrak stations and services, $19.7 billion for the upkeep of harbors and ports, $86 billion for the expansion of broadband access and additional funds to address greenhouse gas pollution and increase climate resiliency..

I can only hope that someone at The Times was not using this initiative as a "pet project excuse" to propose restoring rail service over the Poughkeepsie Bridge.

In his last presser, President Trump in talking about "Phase IV" (not the paint scheme LOL) mentioned the tunnels specifically, saying in what bad shape they were. Somewhere in the background, Andrew Cuomo is smiling and their temporary friendship continues.

His support is based upon the Fed's emergency lowering of interest rates. Can they raise what, $4T (that's $4,000,000,000,000.00) in bonds? Minting special coins? That's for economics.com lol. But in an age where we're playing with funny money, I think Phase IV is a slam dunk, and you know to get support, it's going to include such items, and Amtrak is definitely going to benefit.

A lot of worthwhile public works infrastructure stuff got built during the Great Depression. This is an opportunity to fix the bottlenecks, also might be the only opportunity to get lower bids for big projects. Have to be firm on overruns though.