It was a weird time for public transit. Cable cars could traverse hills, but they were already obsolete: cramped, slow, dangerous, expensive. Buses that conquer those hills today with relative ease were not quite ready yet. And streetcars, the preferred mode of public transportation, came with heavy bodies and slippery wheels that couldn’t handle the 14.4% climb of the Church Street block that gave Dolores Park such beautiful views — let alone the 19.3% ascent two blocks later, followed by an immediate roller-coaster-like drop.

And so, Bion J. Arnold went full Robert Moses. He proposed cutting a trench inside a park to create a new street, then continue that street through a bunch of existing buildings, and then — when the going got really rough — put that street inside a popular solution du jour: a tunnel.

But the Board of Supervisors was not impressed. This felt like an expensive, drastic incision, with half of its immense cost swallowed by land acquisition from property owners. The Twin Peaks and Sunset tunnels, cutting through some of San Francisco’s biggest hills, seemed unavoidable. This one felt like overkill.

The city solicited other ideas, and a dozen ideas came. One suggested building a viaduct connecting nearby streets. Another one cutting off the top of the hill — somehow — to reduce the incline. Someone came up with an awkward cable assist proposal, or a battery of few small bridges. All of these solutions were eventually discarded, but they all needed to be looked at, and that took a long time: out of all the planned new lines, J was the only one that failed to be ready in time for the Panama–Pacific International Exposition of 1915. The press reported with exasperation that “another scheme for disputed railway bobs up to cause still further delay.” The official, usually dispassionate reports mentioned “considerable useless and costly conflict.”

The eventual solution to the J problem was surprising and ingenious. It was revisiting Arnold’s original idea, but multiplying it by a simple realization: a streetcar can still be a streetcar even without a street.

A narrower cut through Dolores Park for two streetcar tracks alone — no pedestrians, no cars — would be cheaper and wouldn’t compromise the park nearly as much. And for the next two blocks, having its own tracks meant the streetcar could snake through the buildings in a more complex way that would allow to smooth the grade, reduce the need for too much of eminent domain, and avoid the expensive tunnel. One solitary turn was now what seemed like a dozen, but the wavy route would not be any less safe given a streetcar is glued to the tracks and doesn’t share them with anyone else — and the whole project would be much cheaper.

After years of frustrations, everything worked out beautifully.

The map on the left shows four blocks where the route otherwise shooting straight down Church Street moves inland: the two blocks between 18th and 20th Street through the edge of Mission Park in its own cut, and the next two blocks with the streetcar snaking through people’s backyards.

(You can also see the beginning of Twin Peaks tunnel and the Eureka Station in the upper left corner, and the Sunset Tunnel — then called Duboce Tunnel — some blocks above it.)

The work to lay tracks started in 1916: