As a commenter there notes:
The local tracks at Smith-9th and 4th Ave will be covered with temporary wood platforms. At Carroll Street the local tracks will physically shift over to the express tracks, temporarily, then shift back after 4th Avenue. This means that the express tracks can't be used to turn back the 'G'. The 'G' must go to Church Avenue, where it will use the the ramps and switchovers south of Church to turn back, or turn back at 18th Avenue using the center track.And commenter Scott adds:
In other words the MTA is misleading us. The 'G' will be extended to Church, but only during the construction project for operational reasons. It will return via the local tracks as the xpress tracks will be out of service.
Also, part of the project includes the replacement and upgrade of the switches at 4th avenue to allow trains to switch between both local and express tracks (and to upgrade to CBTC switches) allowing greater operational flexibility. This suggests that MTA is exploring additional express service and re-routings, otherwise, there would be no need to add additional switches and cross-overs.What I'd like to see is a little more transparency from the MTA, and a firm commitment to restore the F express service. If work needs to be done at Bergen Street before express service can resume, it should be performed while the Culver Viaduct rehab is under way. We cannot afford to wait for additional repairs after the viaduct work is completed.