San Francisco Turntables:

Mission Bay & Bayshore
Turntable Plans
San Francisco

Bayshore's original turntable was an 80 foot S.P. Common Standard unit. Wx4 staff has no statistical information on Mission Bay, but an educated guess would be that it originally had a turntable identical to Bayshore's, but it was replaced in the 1920's with the 100 foot C.S. pin-connected pony truss shown below. Ashland Oregon had a similar 100 ft. table that was constructed in the 1920's.

Bayshore, however, kept its short table until 1941. Earlier, Bakersfield had its 100 foot turntable replaced with a larger model, rendering it available for lengthening and installation at Bayshore. Thus, the Mission Bay table represents a good 'before' example of what SP converted. Since Mission Bay was primarily a passenger and switching loco facility - SP's GS-4's had a wheelbase of roughly 95 feet - the 100 foot design continued to be adequate to needs there.

The lengthening process of the former Bakerfield table was straightforward. Ten feet was spliced into the center of the bottom truss chord, and the top chord, the pin-connected link, was replace with a longer girder section. New center diagonals, various gusseting / bracing, timbering, and operator's cab were constucted along with the modifications required to fit new R.W. Young & Co. trucks.

The pit needed considerable attention, because it, like everything else at Bayshore, was constructed on fill, and the bottom probably sat below sea level. In widening the pit, SP drove 198 untreated timber pilings (curiously, the plans don't state their length) were driven around the outside of the new pit to support the concrete above. Before laying cothe concrete, workers applied three layers of "membrane" (probably heavy tarpaper / felt) and four layers of asphalt. The new 8x8 foot center block also sat atop new pilings.

Below you'll find photos of both turntables, and on page 2 (opens in a new window) you'll find reproductions taken from the original 1941 conversion blueprints.

The photographs below are from the collection of George Solimine Jr, photographer unknown.

Mission Bay 100' Common Standard Turntable

The top chord of each truss consists of two flat steel bars connected to adjoining steelwork at either end by large pins, hence the name 'pin-connected' pony truss. Many early twentieth century SP through truss (river) bridges were also of the pin-connected variety, but in their bottom chords. 1959 photograph

The operator's cab shows in the above 1953 photograph.

Bayshore's 110' Ex-Bakersfield Turntable

Right off, you'll notice that heavy-duty replacement for the top chord.

(left, below) Those are some beefy gussets, eh?

The rounded housings at the photo's bottom right contain the motor and the drive.

Page 2: Bayshore Turntable Plans