In the late 1950's the State of California planned a dam across the Feather River
at Oroville which would indunate quite a lot of the Western Pacifics trackage so the WP re-located
the line to the west over a 23 mile route. It involved building 5 new tunnels and two new bridges.
One of the bridges was a massive concrete arch built over the Feather Rivers North Branch. This is
a somewhat simplified version of that single track bridge.