The scope of work for the installation of SANDAG-furnished traction power substations (TPSS) along the Metropolitan Transit System (MTS) Trolley Orange and Blue lines consisted of installing fourteen 1.5 megawatt and two 2 megawatt, 12kV AC, 650V DC TPSS and the decommissioning and removal of eight existing substations. The locations were within the Cities of San Diego, Chula Vista, Lemon Grove, La Mesa, and National City. Work included site preparation; existing facility removal and decommissioning; grading; utility work, including water, storm drainage, fiber, electrical, and signaling relocation; site improvements, including access roads, fencing, wall construction; TPSS foundation pad construction and associated duct work and ground grid; OCS modifications; and procuring all materials and performing all other work necessary to complete construction in accordance with the project plans and specifications.
Under the SANDAG TPSS Installation Project, Shimmick performed a vast retrofit of the Overhead Catenary System on the Orange and Blue Lines of the San Diego Trolley System (MTS). Work included the installation of new section insulators, in-span insulators, lightning arrestors, feeder assemblies, disconnect switches, tie switches, hanger assemblies, equalizing jumpers, etc. In addition, the OCS was reconfigured at each of the new TPSS sites as well as at the locations where old substations were being removed. Where substations were being removed, the OCS work consisted of removal and salvage of existing insulator assemblies, disconnect switches, feeder assemblies, and lightning arrestor assemblies. At these locations, messenger and contact cables were spliced together once the insulator assemblies were removed. All OCS work performed on the project was performed during off-revenue hours, with windows of time between 90 and 120 minutes per night. Shimmick self-performed all the OCS work on the project. The work was performed by Local 47 linemen, and hi-rail bucket trucks were used during the installation of all OCS components.