• All Things Portal Bridge: Amtrak and NJT Status and Replacement Discussion

  • This forum will be for issues that don't belong specifically to one NYC area transit agency, but several. For instance, intra-MTA proposals or MTA-wide issues, which may involve both Metro-North Railroad (MNRR) and the Long Island Railroad (LIRR). Other intra-agency examples: through running such as the now discontinued MNRR-NJT Meadowlands special. Topics which only concern one operating agency should remain in their respective forums.
This forum will be for issues that don't belong specifically to one NYC area transit agency, but several. For instance, intra-MTA proposals or MTA-wide issues, which may involve both Metro-North Railroad (MNRR) and the Long Island Railroad (LIRR). Other intra-agency examples: through running such as the now discontinued MNRR-NJT Meadowlands special. Topics which only concern one operating agency should remain in their respective forums.

Moderators: GirlOnTheTrain, nomis, FL9AC, Jeff Smith

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  by F-line to Dudley via Park
 
JoeG wrote:I, too, thought they were going to build a new 2-track bridge and fix the old one to provide 4 track capacity. When the new Amtrak tunnels get built they will need the capacity. Of course, whether the new tunnels will be built in my lifetime is still not clear.
No. Because in addition to replacing a bridge that's crumbling, the new bridge is going to be a high fixed span that never has to open. That alone increases throughput and reliability by a huge margin even with the existing tunnels because the current movable span has to open daily for boat traffic. 2 tracks on this bridge have much higher capacity than 2 tracks on the old bridge. There's absolutely no reason to keep the old movable bridge as a second span when it's going to chew through openings all the same, still be restricted to 60 MPH vs. 90 on the new span, and still going to be a high-maintenance bridge that can get stuck, be susceptible to boat/barge strikes because of how low to the ground it is, and has so much wood on it that it's got an elevated fire risk. You've got to amortize these costs over a 75-year rated lifespan between rehabs. As expensive as this fixed bridge is going to be, it's not going to be anywhere near as costly to maintain or operate as a rehabbed ancient-design swing bridge.

If they want to revive the ARC-canceled Portal South span later when Gateway's built that's going to be a much better deal for getting the 4-track capacity than trying to do anything more with the old bridge. And they don't necessarily have to do the second span in-tandem with Gateway because the higher-capacity first bridge can probably keep up with the traffic increase OK--maybe not superlatively, but OK enough--for the many years it'll take to fish for money for the later South span.
  by Matt Johnson
 
At one point at least the plan was for two new 2 track bridges:
  by DogBert
 
ApproachMedium wrote:That bridge is a piece of crap now. It might have been great 100 years ago but with the amount of traffic etc thats going across it refurbishing it is not the answer. To refurb it even properly you would need to take it out of service at various points of time which will cause traffic delays. Replace it with something bigger stronger and that does not open next to it and haul it away. in 104 years the economy has changed, the trains have changed and having a movable bridge link there anymore is just not feasible. Even when the bridge does open and works correctly it causes all kinds of delays because of the amount of traffic in the area.

Penn station isnt something to compare a bridge to that sits in the middle of the meadows. There is no beauty to it. There is no luster. Its a big steel riveted thing that carries trains. If you wanted to see it saved somehow they could float it down to where DB draw is and let it replace that or hog up more space in the river there. Other than that its just a problem waiting to happen. How many times does it need to go on fire? Fail to close? Derail trains?

Exactly. That there has only been one derailment (at least in recent times) is part skill / diligence on behalf of those maintaining it, and some measure of luck. Sooner or later luck is going to run out, and a high speed derailment is going to be a very ugly affair.

They can reuse the same design when they have tunnels to connect a second bridge to.

There is zero viable comparison to be made to the destruction of old penn station. One was a grand public gateway for riders, the other is a piece of decaying infrastructure in a swamp that no one loves.
  by BandA
 
Wouldn't it be cheaper to build one four-track bridge than two two track bridges? Or is the redundancy in having two bridges better?

Build it now and save money, or is it going to take so long to build new tunnels (despite Boardman's alarm) that it would be a waste?
  by morris&essex4ever
 
Is all that is preventing a new bridge being built funding or are there still studies to complete?
  by Don31
 
Its my understanding that everything is in hand - permits, final design, etc., just awaiting funding......
  by F-line to Dudley via Park
 
BandA wrote:Wouldn't it be cheaper to build one four-track bridge than two two track bridges? Or is the redundancy in having two bridges better?

Build it now and save money, or is it going to take so long to build new tunnels (despite Boardman's alarm) that it would be a waste?
I think it's actually a physical limitation with the location rather than a design choice. North River Tunnels are 3 miles away from the bridge with Secaucus Junction at the halfway point. No way would Gateway (or ARC) deviate off-alignment until well after it passed through the current station, which means any separated spans across the river would've quickly re-converged on the mile to the station.

What probably pinches the number of tracks on the span is that they can't build an embankment wide enough on the wetlands of the east shore to carry a 4-track alignment onto the new bridge while the old bridge's alignment must remain active through duration of construction. Obviously they can't suspend service to knock down the old bridge and cleanroom a new one on exactly the same footprint. The physical location of the replacement bridge and its approaches has to shift 100-200 ft. north or south in order to construct it adjacent to the still-active old span.

Under the ARC plan the North Portal Bridge would've been 3 tracks and the South Portal Bridge 2 tracks, so 3's the limit for that location. If a 2-tracker on the single-bridge design works well enough, then a future South span probably can be constructed triple instead so it wouldn't matter if Portal North was 2 or 3. But any which way you slice it there's no way to build one single span that's 4 tracks so deep long-term there'll probably have to be a second span to track with demand (though they can probably safely defer bridge #2 until after Gateway is open for business, so there's no upside to funding it sooner).
  by zerovanity59
 
This bring up an important point. What is the true bottleneck of the NEC between Newark Penn and New York Penn? I hear it is the Portal bridge one minute, the north river tunnels the next, and New York Penn the third minute, or does it vary depending on time of day.
  by ApproachMedium
 
All of it. The railroad has simply outgrown two tracks to get to and from penn station. And there are not enough free tracks in the station during rush hours.
  by Greg Moore
 
First rule of optimization (of any process). There is ALWAYS a bottleneck. It can change depending upon many factors (or may not even be a factor in many cases).

So when optimizing one has to be careful not to focus on a single item.
  by bleet
 
Actually there are a number of problems between Newark Penn Station and New York Penn Station besides the Portal Bridge and the Hudson River Tunnels.

There are only two tracks between Portal and Newark and the saw-tooth bridge is also on it's last legs.

But you have to start somewhere.
  by zerovanity59
 
I thought the route goes from 4 to 3 in the middle of the Harrison PATH station and from 3 to 2 right before the Portal bridge. It becomes four immediately after the bridge for Secaucus "junction" and then to 2 for the tunnels.
  by bleet
 
It's 2 from the saw tooth bridge to the portal bridge i believe.
  by ExCon90
 
The 4 tracks through Secaucus Junction are to permit trains to make a station stop without slowing down the nonstops. The extra track capacity is essentially eaten up by the increased time taken by stopping trains.
  by Greg Moore
 
A more article on the Portal Bridge.

I'm starting to wonder if Amtrak is getting better at media relations and just slowly, but continually getting more noise about this and Gateway.
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