I49 in LA

[sparker]

At this point (6:30 pm PDT) according to the reports it looks like Ida's doing what previous hurricanes have done and followed distinct waterways inland -- in this case, heading for the Atchafayala River.  We'll have to see how the I-10 bridge system holds up when the eye passes over it.  I'd expect extensive flooding over the I-49/South corridor length, particularly between Morgan City and Lafayette.  Wouldn't be surprised to see the area from Baton Rouge west to about US 165 resembling one huge shallow lake by the end of the day.

I'm sorry, what? The threat from Lafayette north and west is far less now. The eye of Ida went just to the west of New Orleans metro, and is traveling north between Baton Rouge and Hammond. It won't cross the Mississippi River going west again or the Atchafalaya River.


iPhone

Just extrapolating from earlier reports around the time of the landfall; looks like the eye curved around and headed directly north from there rather than the usual waterway-following pattern.  Last report I saw showed US 51 through Laplace fully inundated (the I-10 causeway visible in the background); projections are a downgrade to a tropical storm but with up to 20" of rain to the east of the eye (which is likely, from the charts shown tonight, to pass just west of Jackson, MS).  Meanwhile, we're still a tinderbox out here in CA; just waiting to see if South Lake Tahoe will still be standing by next week, but choking on smoke in the meantime.  Mountain or bayou -- the current climate situation featuring exaggerated weather patterns isn't sparing anyone!   

[Anthony_JK]

This is actually pretty relevant to how Future I-49 South will be built.

It appears that the core of Hurricane Ida went straight through the Barataria Basin, that stretch of low-lying wetland area between Raceland and Boutte; existing US 90 is at ground level and was completely submerged by the 7-11 foot storm surge.

One of the original plans for constructing I-49 South was to fully elevate it all the way across southeast Louisiana from Raceland to the section in Gretna where the Westbank Expressway begins its elevated freeway section, as well as build it on new-terrain alignment outside of US 90 from west of Des Allemands to Boutte. That concept was rejected, however, as too expensive; LADOTD decided to explore a different approach where the proposed freeway cannibalized most of the US 90 ROW save for a brief bypass east of Des Allemands and west of Boutte. The new approach would effectively cut off US 90 between Paradis and Boutte from local traffic and local access, and would require repairs and replacement of the current US 90 bridge across Bayou des Allemands. It would also overlay the existing US 90 roadways east of LA 1/LA 308 at its existing height.

In the aftermath of Ida, I'm wondering if they will reconsider the concept of elevating on viaduct at least portions of US 90 or going more new terrain route to preserve existing US 90 for local access.

The current environmental studies for the Raceland to NOLA segment, as well as the segment through Patterson/Bayou Vista/Berwick, are on hiatus; but I'm expecting that funding from the infrastructure bill will be used to revive and complete them; and there will be renewed pressure to get the funding to complete I-49 South (and also probably the LA 1 Gateway to the South toll connection to Port Fourchon/Grand Isle, provided that the latter is still afloat and not washed into the Gulf).

[Henry]

It seems that elevating I-49 should be a no-brainer, and in the aftermath of Ida, the state will most likely regret the time they rejected that idea.

[Bobby5280]

The problem is cost. People responsible for designing and building highways in the United States don't appear to have any ability to build bridges that don't cost an outrageous fortune. I agree it would be a great idea in principal to elevate much of I-49 South between Raceland and Gretna. But the cost would be astronomical. On top of that the Louisiana state government has the burden of needing to overhaul and expand I-10. That existing Interstate has a several very long bridges that are getting really old and badly need expansion from 4 lanes to 6 lanes. I almost forgot the Southern end of I-55 is a similar can of worms.

[cjk374]

I almost forgot the Southern end of I-55 is a similar can of worms.

Yep. The first 22.6 miles of I-55 is all bridge...just 1.2 miles shorter than the Pontchartrain Causeway.