The "Cal-P" is technically Mtz-Sac only because the California Pacific was built from Vallejo to Napa Jct, Suisun City, Davis, and Sacramento (with a branch to Calistoga and another to Woodland, Knight's Landing, and Yuba City, where it was projected to go up the Feather River canyon and through Beckwourth pass to points east). Except for Pinole, there were no signal bridges until you got to Richmond. Then all the way to Oakland Pier, virtually all the signals were on "bridge" type signal bridges, but this was then.

That old signal bridge you mentioned in Pinole was about 1500' west of RV20, which is what used to be the station of Hercules (for the powder company).