Hi Jose an all,
A quick search on the Library of Congress site turned up 4 more photos - 2 of them during the rebuild.
The caption for #14 gives the game away - TURNTABLE PIT: Photocopy of December 1940 photograph of the turntable pit at Bay and Taylor Streets. View is to the north. Market Street Railway was in the process of moving the turntable from its original location, where the car is being turned in the background, to its present site. - San Francisco Cable Railway, Washington & Mason Streets, San Francisco, San Francisco County, ...
4 x 5 in. http://www.loc.gov/pictures/resource/hhh.ca1237.photos.016247p/
They are installing the new turntable further up the old return line. The right hand track leading to the new pit is a new arrival track. So yes that is the haulage rope between the rails across the new pit. The haulage rope could probably have still been in service when this photo was taken.
#16 TURNTABLE RECONSTRUCTION - BAY & TAYLOR: Photocopy of January 1941 photograph taken during reconstruction of the Bay and Taylor turntable. View to northwest taken two days after CA-12-22. Reconstruction work is nearly complete in this view. - San Francisco Cable Railway, Washington & Mason Streets, San Francisco http://www.loc.gov/pictures/resource/hhh.ca1237.photos.016249p/ The haulage rope would have to have been rerouted when this photo was taken. The new "Let Go" point would be behind the photographer.