They are rehabilitating the entire viaduct structure (which is steel and concrete). The concrete is in such bad shape that chunks were falling off, which is why the entire structure is wrapped in that black netting.

In addition to rehabbing the structure itself, they are also rehabbing the track bed structure, installing new rails, signals, and switches (to make everything CBTC ready), they are doing a full station rehab of smith-9th Street and installing elevators, and making key repairs to 4th avenue which, as I understand it, includes replacing the canopy and doing some repairs to the platforms and rehabbing the tower at 4th Ave.

I am not sure if this is going to be performed in conjunction with the tunnel lighting projects that are taking place between E.Bway and Carrol and 4th Ave to Church.

Express F Train: budgets aren’t infinite. Before the MTA would add a fourth track to the existing 3-track lines, someone needs to demonstrate that there’s a demand for that capacity, and that it’s more pressing than other subway investments we could make. It’s unlikely you could make that case. On the lines you mentioned, the heavy demand is mostly during rush hours in the peak direction, and a 3-track configuration can satisfy that.

What’s more, the West End and Astoria lines currently have no express service at all, and I haven’t heard of any community desire to provide them. The Astoria Line actually had express service a few years ago, and the community asked the MTA to change it back to all-local. Demographics have changed since the line was built, and the local stations are now more popular than they originally were.

As I understand it, there will be a hard track connection made just south of the carroll street portal that will shift trains from the local to express tracks (and vice versa in the opposite direction). Platform extensions will be built at Smith-9th and 4th Ave allowing riders to use those stations even though trains will be on the express tracks. Because the express tracks are being used for service, the G cannot turn around at 4th avenue and is being extended to Church where it can turn around.

The problem is that there is not enough capacity on the tracks for the F (as it is currently routed), the G, and an F or V express to all use the same tracks.