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.