BATH (AP) — Maine officials say the construction of a new Bath Viaduct is ahead of schedule.

The viaduct resembles a bridge and it carries traffic through Bath’s downtown and by Bath Iron Works shipyard. State engineers said last year that the viaduct’s roadway and supporting piers were worn out.

The project to replace the viaduct is expected to cost $15 million. The Maine Department of Transportation says 15 of the 19 pier columns have been completed, 10 of 19 pier caps are finished, and the first 20 superstructure spans are now put in place.

The DOT says the work is approximately three weeks ahead of schedule. The agency says drivers should expect daily lane closures through April. The new viaduct is expected to be open by Memorial Day.