How BART replaced a key transformer in the core of the system on a whirlwind schedule

A Bigge crane brought in for the transformer project is pictured besides the BART tracks.

Read more stories about BART infrastructure and big building projects at bart.gov/railtales. 

A newly energized transformer near the core of the BART system is expected to improve the customer experience by increasing power redundancy and resiliency. This translates to increased reliability in the key passage that connects the East Bay to San Francisco. 

The transformer was installed on a whirlwind six-month schedule to ensure the area, so crucial to BART’s busy Oakland Wye in the center of the system, had sufficient backup power in case one of the other nearby substations must be taken down for maintenance. The Oakland Wye refers to a triangular junction where BART trains can switch between multiple lines.  

“All five lines run through the Oakland Wye; a train is going through it every two to three minutes during peak commute, so it's important to have massive redundancy here to mitigate delays and keep trains running,” said Gordon Wong, Principal Electrical Engineer who wore many hats for this project. 

A Bigge crane removes the original transformer on May 17, 2025.

The nearby substations operate at the same time, their transformers and rectifiers fulfilling their job of converting 34.5kv voltage fed via sub-transmission cables from the power grid into the 1,000 DC voltage train motors require to run. 

The old transformer, located between Fruitvale and Lake Merritt stations, needed to be replaced after reaching the end of its life after 20 years of service. BART Traction Power engineers made the decision to replace it after regular maintenance testing alerted staff that the equipment was at risk of failing.  

“Myat deemed this year the ‘Year of the Substation,’” said Asst. Chief Infrastructure Delivery Officer Manal Bishr of her colleague Myat San, BART Chief Infrastructure Delivery Office. “We gave him a little bit of a hard time about that, but it’s really motivated the team. This is huge for providing power to the core of our system!" 

Left to right: BART Traction Power Electricians Javier Morales and Robert Flores install high-voltage wiring on May 28, 2025.

By removing a transformer near Dublin/Pleasanton and reinstalling it at this Oakland location, BART saved a significant amount of money and honored the agency’s sustainability values. Only one line runs from Dublin/Pleasanton to Bay Fair, and trains have lower frequencies. This means the area requires less power to operate. 

“We saved at least $500,000 and three years of work by using a pre-existing transformer,” Wong said of the project, which was funded by voter-approved Measure RR. “This project cost half the price of furnishing a new transformer."

Moving a transformer is no simple task, and multiple departments supported the work, including Traction Power Engineering and Maintenance, Structural Engineering and Maintenance, Integration Engineering, Operations Liaisons, and System Access. In addition to Bishr, San, and Wong, the project was led by BART’s Zeeshan Ali, Adam Flynn, Michael Gibson, Andrew Holcomb, Ravi Raj, Andrew Shuck, Thaw Tin, Juan Ulloa, and Damon Williams.  

BART Traction Power Electrician Javier Morales works on high-voltage wiring for the transformer installation on May 28, 2025. 

Transformers are giant pieces of equipment, weighing about 30,000 pounds – about half the weight of one BART car. What goes on inside a transformer? Simply, power comes in from one end, and windings step down the voltage to convert it to the correct voltages. Three megawatts is the full-rated capacity of the transformer in question.  

The most cinematic moment of the process was using a crane to lift the transformer lay it on its concrete foundation. Bringing in a giant crane required months of legwork. A significant amount of vegetation needed clearing, then BART needed to secure permits with the Union Pacific Railroad, with which BART has an easement. 

Left to right: BART Senior Electrical Engineer Henry Nguyen and Junior Engineer Artem Morozov  work on the installation of the transformer on May 28, 2025.

It was a celebratory day when the crane made its triumphant appearance at the work site. After a semi-truck dropped off the crane and its counterweights, the rigging crew had to assemble it – it takes three hours! -- and used a giant forklift to roll it into place. Then the team had to wait for “the blanket,” A.K.A. the small window at night when trains aren’t running for passenger service. When at last the time came for the crane to lift and place the transformer, the team exhaled. In all, the lift took about thirty minutes. Planning out the moment, however, required months of labor.  

After connecting the primary 34.5kV cables, the Traction Power team energized the transformer and listened to the sweet sound of its internal winding heating up as energy surged through and trains zoomed past.  

Contractors on the transformer project included C3M, Clark, Cupertino, Azul, Biggie Crane, Rigging Rail Pros Flagging, CEL Soil Sampling, and Novoa testing.