For two weeks in September, work crews from the SFMTA will resume work on the west portal of the Sunset Tunnel, where the N-Judah emerges in Cole Valley.

Unlike previous efforts to repair and seismically strengthen the 88-year-old subway tunnel, the transit agency says work will only occur during daytime hours, and will not impact service on its busiest streetcar line, which serves 48,000 riders each day.

In the first phase, which starts on September 6th, workers will dig a trench along the tunnel's south wall before filling it with concrete. Although Richard Gamble Memorial Park will remain open during the repairs, the dog park's east entrance and the walkway that connects Clayton and Carl Streets will be closed from September 12th-16th.

During phase two, workers will dig a trench along the north wall to improve earthquake resistance. A 24-hour parking restriction will be in place on the north side of Carl Street and east of the LRV tracks for the duration of the work. According to Muni, 10 spaces will be used as a staging area for tools and equipment.

The Sunset Tunnel Trackway Improvement Project was initially scheduled to unfold over 15 weekends starting from the summer of 2014. But weather delays and noise complaints from residents extended the project's timeline. In October 2015, SFMTA estimated that five more weekends of work were required to wrap things up. (The last time the SFMTA worked on the Sunset Tunnel was the weekend of April 15th-18th.)

In addition to seismic retrofits, Muni has upgraded overhead catenary wiring, replaced rails, and improved the trackbed in and near the tunnel. The agency also upgraded the tunnel's fire safety system, created wheelchair-accessible boarding platforms at 28th Avenue, and upgraded traffic signals at nine intersections along the route to speed up travel times.

Residents with questions or complaints are encouraged to call 311 or contact SFMTA project manager Tess Kavanagh at [email protected] (415-701-4212).