We view this transfer in stages. If we're up for it, we can simply have an above-ground transfer at the current J-Church stops along Church Street. Or, to facilitate this transfer, we could build a short pedestrian tunnel to add an additional exit right to the platforms on both sides of Market. Currently, the transfer speed is about 1 minute from platform to platform northbound, 1.5 minutes southbound. Extending the entrances to the platform (and adding additional east-side underground staircases and faregates to the platform) could cut this time down to 30 seconds. Even today, with no infrastructure improvements, if a K, L, or M will arrive within 4 minutes, it's faster to disembark the J at Church, and walk down to the underground platform than to wait for the J to merge in.

Either way, ultimately we view bringing the J and the N underground as essential to maximizing the transferability between lines, as well as to speed up trains between Sunset Tunnel and Church Station on the N and Dolores Park and Church Station on the J.

The most simple option is the cut-and-cover model to bring the J-Church underground just after Dolores Park. The hill is steep along Church, and the train could enter a flat tunnel immediately north of 18th Street while the road climbs upward. When done effectively, cut-and-cover subway models have been built for less than $30M/mile of track, and we're talking less than a half mile here. Another option is, should the city succeed in working with Safeway to redevelop the triangle between Duboce, Church, and Market, any new development (as well as the grocery) could receive direct subway exit access in exchange for allowing the J church to veer north along Webster from Church as part of the infrastructure construction. This could set the stage for an underground tunnel from Church Station all the way to Hayes and Webster (with an underground stop at Haight & Webster), where the J could emerge as a surface-level tram on the rather large Webster Street.

For the N-Judah, we see the current eastern edge of the Sunset Tunnel as a place to descend the N just below the surface toward Church Station. A relocated Duboce Park station could be partially or fully underground just west of the current station. As the train intersects with Church (where the J would cross perpendicularly), underground transfers are in order, with moving walkways to express to the M-Market platform. Continuing just below the surface, the N would head east along Duboce just past Market before potentially emerging as a surface-level tram along Duboce to Mission Street.