WALK Bridge South Norwalk (Replacement, Status, etc.)

True to both. Of course, you're talking about replacing a bridge along the busiest corridor in America....

https://www.thehour.com/news/article/wa ... 096066.php

$1B replacement of 127-year-old Walk Bridge in Norwalk begins — setting up faster train rides to NY
NORWALK — Construction has officially begun to replace the Walk Bridge — an about $1 billion project to upgrade the 127-year old steel swing rail bridge that spans the Norwalk River by the Maritime Aquarium.
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But the old Walk bridge has far exceeded its operational life of 100 years. By 2011 a pattern of bridge failures had begun to emerge as the bridge failed to “swing” to switch between allowing rail and sea traffic. In 2014 the bridge failed to open twice within a two week period. In 2013 it failed 16 times out of 271 openings, according to the Connecticut Department of Transportation.
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Construction will take six years. The old swing design will be replaced with a “vertical lift bridge” that will lift two movable spans 60 feet vertically to permit sea traffic. Several other bridges in Norwalk will also be upgraded using project money.

The vertical lift design allows the new bridge to be built in pieces. Two tracks will remain operational throughout construction. If all goes according to DOT plan there will be only two weekends of track outages during construction.
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They haven't even started actual construction yet?! What have they been spending all this time on then?

Pre-construction activities such as Dock yard, utility relocation, switch installation. It’s in the article.

daybeers wrote: ↑Sat May 13, 2023 7:57 am They haven't even started actual construction yet?! What have they been spending all this time on then?

It has been complicated. Track #3 across the swing bridge will be taken out on each side of the water. In its place the southern columns ( 1 on each side of water ) for the north lift bridge will go up. During that time only track 1 will cross the swing bridge. Eventually track 1 will be moved north with the north columns north of relocated track 1.

The preliminary work installed a new CP east of the bridge to enable tracks 1 & 3 to be routed westward over swing bridge on tracks 2 & 4 near end of final work on north lift bridge. Then 1 & 3 will be permanently installed on north lift and put in operation. The wash, rinse, and do same for south tracks 2 & 4.

Just how the movement northward of tracks 1 &3 over new lift bridge ill happen but several ways possible. Tracks 1 & 3 and eventually 2 & 4 will be raised to add more free board clearances to the water. As well that allows the lift bridge to be in use above old swing bridge until south lift bridge complete. So trackwork and CAT will need to be raise on slight grade to the higher altitude of new lift bridges.

FRA Award (PDF): FRA.DOT.GOV

Connecticut – Walk Bridge Replacement (Up to $465,000,000)

The proposed project includes construction to replace the existing Walk Bridge, a 127-year-old four-track, four-span, movable bridge over the Norwalk River in Norwalk, CT, with a new multispan bridge that will include 240-foot dual lift spans over the waterway and fixed east and west approach spans. The scope also includes embankment work and retaining walls, removal of the high towers, rerouting of transmission lines, a new fender system, and track and rail systems work. As matching funds, Connecticut will provide $87,187,500 and Amtrak will provide $29,062,500.