UPDATE CORRECTION: The OB stop at Park Presidio should not be affected by this repair work. The OB stop at 12th wil https://t.co/1MKL7A7oUt (More: 24 in last 48 hours)

Update: Slow Subway Service This Past Week

Wednesday, September 12, 2018

Twin Peaks Tunnel

Over the last 72 hours, Muni Metro riders have been stuck in significant delays. We want to take this opportunity to explain what has been going on and what we are doing to fix it. As you might have heard, we finished Twin Peaks tunnel work on time on August 25th. This work was necessary to improve the tunnel’s tracks, walls and drainage systems so it can continue to operate safely and reliably for years to come. Initially, the rail service was running as intended.

This past weekend, the contractor for the Twin Peaks project completed the first of two nightly weekend shutdowns (the second will occur this weekend) to perform some routine tasks as part of the project requirements. It appears that the equipment the construction crews were using damaged some of the components that make the automatic train control system work correctly (automatic train control is the feature that controls the train within the subway, while our operators drive the train on the surface).

Early Saturday morning we began to experience anomalies in our train control system that randomly stopped some trains from entering West Portal station (this is where K, L and M trains switch from manual operation to automatic operation). When this happens, the only way to move trains through the area is to proceed at a significantly reduced speed to Forest Hill station (the next stop). Once the operator gets the train to Forest Hill, they can then proceed at normal speed. Unfortunately, operating at the slower speeds in this portion of the subway significantly slows service in the entire metro system. Despite our attempts to fix the issue everytime it occurs it continues to persist.

Our transit team immediately began troubleshooting this issue over the weekend and replaced all components of the train control system. Still, the problem persisted. We have also been working with the train control system manufacturer to address the issue. They are currently gathering data that is being analyzed and can be used to specifically identify the problem area so we can make the fix. We believe that we will have a solution in place as early as this week.

In the meantime, should the delays continue, we have positioned staff at West Portal station in an effort to make mechanical and electrical adjustments to keep the trains moving and service running. We are devoted to finding a solution as soon as possible. We appreciate your patience and apologize for any inconvenience this may have caused. We will keep you updated on our progress.