The Potrero Tunnel

Whilst trying to find a 4yr olds birthday party on Google Maps recently, I was telling a coworker how amazingly awesome Google Maps is when I noticed this strange diagonal line that goes through Potrero hill. I know there are train tracks at the bottom of Potrero, but never really though about where they went to.

It turns out there was once a tunnel underneath Potrero Hill; which collapsed in 1960. E writes in a blog comment:

The tunnel you’re describing under Potrero Hill was originally dug by the Ocean Shore Railroad in the early 1900’s. When the Ocean Shore went bankrupt in the early 1920’s the Western Pacific inherited the tunnel and some of its industrial trackage. In the early 1960’s the tunnel under Potrero Hill caught fire and burned. The fire caused parts of Potrero Hill to cave in and pictures of sinkholes caused by the collapsing tunnel can be viewed on the San Francisco Public Library’s website. In the early 1990’s a new building was constructed on 18th st between Deharo and Arkansas. Prior to this buildings construction an empty lot with rails leading into the hill marked the location of one of the tunnels sealed entrances. A newer patch of pavement leading straight into this newer building can still be seen on 18th st directly in front of it. This marks the location of the tracks leading to the tunnel. The other side of the tunnel is on Private property and cannot be viewed or accessed.


Pics are excerpted from Google Maps and copyrighted as such. The first shows fairly clearly the path of where the tunnel used to be. The second shows a train still hiding at the base of Potrero.

In researching this blog post I also learned about another arterial railroad into the city and the cause of many of our oddly shaped buildings in this excellent peice of imagery. (Big image, but worth examining)

It’s amazing how much history is right under our noses.

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One thought on “The Potrero Tunnel

  1. Fascinating.

    That explains why there are so many warehouses in that diagonal slash through the flat part of the Potrero Hill area. It looks like in several places the tracks are now 18-wheeler parking lots – about as minimal a change as possible.

    The big image also explains why Treat St. is at that odd spot (near 16th and Harrison, where the tracks turn, I guess there was a switch) and why huge warehouses like the one Mission Cliffs is located in were there.

    I always figured the trains went due West from the yard near 4th and King across on Division, but I never knew they went that far (never really thought about the fact that rail was the only heavy cargo option for a long time), nor that there was a tunnel. Cool!

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