The Dumbarton swing bridge is an abandoned railroad bridge that runs across the San Francisco Bay just south of the Dumbarton Bridge (Highway 84). Built in 1910 and abandoned in 1982, the bridge carried freight over the south end of the bay. A bridge operator would sit in the house on top and swing the bridge open if a tall boat needed to pass through. This 10 minute exposure with the moon 64% full shows star trails and planes taking off and landing at SFO airport.
The hike down the abandoned railroad tracks is just under 2 miles. The bridge is bordered by a water treatment plant and wildlife refuge. We saw people working at the plant during our hike, a lot of birds, and almost got sprayed by a skunk. This view from the marsh area next to the bridge is a 15 minute exposure. The airplane flight path was pretty consistent over this time, and the plane trail reflections are also visible in the water.