How about the reducing the F, which for a decent portion of its route down Market is directly above the underground KLM lines? The F is slower and lower capacity per car and stops at lights (and stops traffic when it needs to turn) in addition to apparently being more costly to run. I am clearly not a transit planner or traffic engineer, but it seems perfectly reasonable to run the F only from the Ferry Building to Fishermen's Wharf.

- People who want to go up market can transfer to the KLM at Embarcadero and if they're going to Castro (or maybe Church?) they may also get there faster.

- If tourists want to see an old-timey street car, they could ride one perhaps half the distance, only along the water with views Coit tower, and the eastern end of the line would be right by the Railway Museum anyway. And we could run perhaps half as many cars.

The part that runs on Market Street is the useful part. The part that runs along the Embarcadero isn’t useless, but it’s more seasonally useful. I’d rather see the old PCC cars replaced with a solid modern low-floor LRV using more standardized parts & aggressive transit policing to keep freeloaders from abusing the system. It is partially redundant with the subway, but if you’re going to have a surface street railway anyway, I’d rather it be optimized for local use.

You could pull the J up from underground too using the same low-floor LRV model chosen for the new F, having it turn at Church & Market rather than making an awkward diversion to Church & Duboce first.