As best as I can tell, the railway refers to a part ofd the Southern Pacific lines that goes through Rose Canyon east of La Jolla, and in San Diego. I know the area because the Union Brick Company was once located there. Union Brick may have gotten some of its clay from the southeast slopes of Soledad Mountain, in a pit still visible off Loring Street. The area is now condominiums and private land but the homes are situated in a crater. This writer was briefly able to view the site. How SP RR gave out complimentary passes for Catalina Island is still a mystery to me.

http://www.donwinter.com/Railroad%20Infrastructure%20and%20Traffic%20Data/Regions/Southern%20California/Route%20Descriptions/Soledad%20Canyon%20line.htm