The Twin Peaks Tunnel, which connects Castro Station to West Portal on the other side, will be closed throughout this weekend for repairs, and will be closed again in August.

Those who ride Muni to the city's westside will encounter bus shuttles this weekend, stationed at both Church and Castro stations, which will ferry passengers out to the outer stops along the M and K lines.

The L-Taraval remains bus only, though it is expected to return to light-rail service this fall. L buses this weekend will be extended to run between SF Zoo and Church stations.

"The Twin Peaks Tunnel has over a century of service under its belt and needs work to keep up with the demands of time and the Muni system," the SFMTA says in an announcement. "The SFMTA conducts regular inspections and structural evaluations of the tunnel, and expects to make additional improvements to the tunnel over the next 5-10 years to keep it safe and reliable for years to come."

S-Shuttle service between Embarcadero and Castro stations will also be running on a special schedule through the weekend.

The Twin Peaks Tunnel was previously closed June 21 to 23, and the next closure for this year's maintenance will last for eight days, from August 22 to 29, including weekdays (Thursday to Thursday).

Muni bus lines will see various improvements starting next month, August 17, tied to the kickoff of the new school year. Read all those details here.