As of mid-January, the SFMTA was suggesting that the N-Judah might finally be returning to service this month or next. But no. Now it's looking like May.

Some Muni light-rail service came back to life in December and January, but only portions of lines that run above ground — including the J-Church, which will not be going underground anymore and terminates at Church and Duboce. And last we heard, more trains were going to begin running in February or March. But now the Chronicle reports via a slide presentation on transit performance that's scheduled to be presented to the SFMTA Board of Directors on Tuesday that "May" is the new projected timeframe for the return of subway service on the N-Judah and T-Third lines, with no specific date given and no dates for the return of K, L, or M trains either.

What is holding up the return of Metro train service appears to primarily be maintenance projects, including "rail grinding" work that has not begun and will require eight weeks to complete, according to Director of Transit Julie Kirschbaum in the presentation. A variety of projects have been completed in the train tunnels while the trains haven't been running, including installation of a new wi-fi system, the removal of an outdated signaling system, and the systemwide replacement of metal splices — connectors between overhead power lines — that followed the discovery of a batch of faulty splices that were breaking last August, hours after subway service had returned for the first time in five months.

The other major project that Muni didn't know it was going to have to deal with, the result of a blunder by staff and contractors, was the replacement of ballast rock beneath the tracks in the Twin Peaks tunnel that was supposed to be done as part of a previous project two years ago. That project has also now been completed, per the presentation.

Still outstanding is a project to replace "switch machines" throughout the system. "Each switch machine requires its own individual installation design," the presentation says. "Maintenance engineering is working on prototyping to make the design and installation faster."

If and when the N-Judah and T-Third lines return in May, the report suggests that the T will terminate at West Portal station.

Under the newly reconfigured light-rail system, the M and T will run as a tandem line — with trains running the T route heading inbound, to Third Street, and the M route outbound, to Balboa Park. The J remains above ground and terminates at Duboce, and and the former K and L routes become a single line that also remains above ground, traveling between Taraval and Balboa Park. K and L riders that want to reach downtown will have to transfer to T or S-Shuttle trains at West Portal.

But it's looking more like San Francisco won't get to see how this configuration works in practice until summertime.

According to Kirschbaum's presentation, a consultant is being brought in to "analyze emerging service patterns and advise on restoration approach." Also, she says, the "pace of service restoration" is dependent on more federal stimulus funds coming to SF.

Previously: Muni Brings Back T-Third Train, Some Buses This Weekend; N-Judah May Return In February

Photo: Matt Baume