California Code, Public Utilities Code - PUC § 560

Upon the application of any shipper or receiver or contemplated shipper or receiver of freight for a connection between the railroad of a railroad corporation and its existing or contemplated private track or railroad, the railroad corporation shall make the connection, provide such switches and tracks as may be necessary for that purpose, and deliver and receive cars thereover, if the connection is reasonably practicable and can be installed and used without materially increasing the hazard of the operation of the railroad with which the connection is sought, and if the business which may reasonably be expected to be received by the railroad corporation over the connection is sufficient to justify the expense of the connection to the railroad corporation.

Upon the same conditions, every railroad corporation, upon the application of any shipper or receiver or contemplated shipper or receiver of freight, shall construct upon its right of way a spur or spurs for the purpose of receiving and delivering freight thereby, and shall receive and deliver freight thereby.