Soledad Canyon Rd, LA
Photo taken by Craig Philpott in April 2010
BH Photo #163354
This must have been the tunnel used in the 1971 movie "Duel" The scene when Dennis Weaver-(Mann) meets the school bus with Lou Firestone, and the big gas truck that has been chasing Mann in his red Valiant can be seen at the end of the tunnel.
This is the tunnel shown in the 1974 made-for-TV movie the California Kid. Wikipedia mentions it was filmed in Ojai and Piru but there's no tunnels in those areas.
Is this the tunnel in the Twilight Zone Hichhiker episode? Looks very much like it.