Amtrak finished a nine-day rebuild of A-Interlocking in the First Street Tunnel just south of Washington Union Station and resumed train operations on Oct. 26, as scheduled. The interlocking controls every Amtrak and Virginia Railway Express train moving between the station and Virginia.
Amtrak, which called the project "Pause for Progress," says crews replaced switches and crossovers, rehabilitated 350 feet of track and tunnel base, installed 550 tons of ballast, replaced 1,000 feet of rail and 215 ties, and laid 2,500 feet of signal and electrical cable. The new equipment includes eight electric switch machines, two double-slip switches and one crossing diamond.
Service south of Washington was reduced or split from Oct. 16 to 26. Amtrak's plan included a train-and-bus connection for the Carolinian and shortened segments for several long-distance routes, with some Virginia Northeast Regional trains running to Alexandria with replacement buses. VRE ran a modified schedule without service into Union Station, and NBC4 Washington reported riders could use L'Enfant Plaza. Service north of Union Station was not affected.
Before the work, Amtrak said the old switches and crossovers forced trains to slow to 10 mph. Amtrak chose a single outage over phased work because limited access in the tunnel made phased construction impractical, according to its August announcement.
An interlocking lets trains move between tracks and controls their paths through a junction. At this location, that function sits inside a confined tunnel linking Washington with the rail network to its south.
Amtrak thanked VRE, the Virginia Passenger Rail Authority and the North Carolina Department of Transportation for coordinating service during the outage, and CSX, Norfolk Southern and WMATA for accommodating operational changes.
Amtrak says the work will improve reliability for years to come. The completion announcement gives no new speed through the interlocking and no post-reopening performance data, so the reliability gain is still unmeasured.
For passenger rail agencies, the project shows a hard maintenance choice. A busy connection went out of service for nine days to remove worn components, and Amtrak finished on schedule ahead of the holiday travel season. The next milestone is evidence from regular service: whether the 10 mph restriction is lifted and whether delays fall.