Caltrain is now installing overhead catenary, as part of the electrification project. The next step will be to test/validate the electrical systems.
Overhead catenary systems (OCS) is a mature technology, with a large and established market of products and services to test line voltage. Being in Silicon Valley, one might expect Caltrain to use the most advanced of these technologies — or not:
The traction power substations and an overhead contact system (OCS) must be verified to be mechanically and electrically compatible with the new bi-level electric multiple unit vehicles (EMUs). Rather than bringing two new systems online simultaneously, PCEP staff determined it would be in the PCEP’s best interest to first test the traction power system and OCS using a used electric rail vehicle. This staged approach will greatly reduce the likelihood of exposing the new EMUs to possible 25 kilovolt-ampere (kVa) traction power abnormalities.
Staff recommends the purchase of two used electric locomotives: one that will be utilized for testing and the other that will be utilized for replacement parts. After the purchase from Mitsui is complete, a separate contract with Amtrak will provide overhaul services for the electric locomotives, as well as storage, acceptance testing and commissioning, training, and transporting the locomotives to CEMOF.
The budget for the work associated with both contracts is $1.5 million.
Upon completion of the electrification system testing, scheduled for 2020, the Caltrain will dispose of the used locomotives.
So the plan is to spend $1.5 million refurbishing two 40 year-old AEM-7AC locomotives, and use them one-time to do a “smoke-test” on the electrical system — and then throw them away! It is hard to imagine a more expensive and ridiculous way to do line testing.

AEM-7AC being recycled for parts