Bay Area Rapid Transit replacing old third rail
The Bay Area Rapid Transit (BART) will be replacing sections of third rail, along with cable and traction power substation replacement in line with the Measure RR for renewing power infrastructure.
The replacements, currently stored in a warehouse, will be stainless steel-capped, aluminum third rail segments that will be more efficient and economical. The new rail is half the weight of the old and conducts electricity better.
That means easier and faster installation. The old rail weighed in at 27 pounds per foot or 810 pounds for a typical 30-foot segment or “stick,” more than twice the weight of the new rail. The old rail is also six times stiffer than the new, making it tough to position just right. With the new rail, BART can do repairs more quickly, requiring less down time and inconvenience.
The warehouse holds about 2,400 sticks of new rail, at 12 pounds per foot, or 360 pounds per stick. That’s light enough to require far fewer workers to handle. There’s a thick aluminum bar to conduct electricity, covered by a tough stainless-steel cap for resistance to the countless iron paddles from train cars that slide across its top, transferring power to the train.
“Third rail is an important asset for reliability of the power system and continuous train operation,” said Myat San, BART’s group manager for power and mechanical engineering. “The useful life of these third rail segments is about 20 years. As they age, efficiency and performance will be impacted.”
BART’s new third rail will be the thicker aluminum 2 micro-ohm/ft. to reduce voltage drops and improve train performance between substations. Third rail voltage has direct impact on train performance, and thus it is important to maintain it at acceptable levels.
Several years ago, BART tested a new, stainless-capped aluminum third rail product that offered many advantages, and test sections were installed south of Bay Fair Station to see how it performed. After successful tests, BART is moving forward to install it systemwide, replacing legacy 4 micro-ohm rail with the more economical, more conductive, lighter and more flexible new rail. That’s good news for passengers, who can expect a smoother, more reliable ride from the new third rail, the backbone of power for the whole BART system.
“The Measure RR work we are doing to replace substations, transformers, third rail and more, is about reliability and a better experience for BART’s riders,” San said.
BART District voters in 2016 approved the Measure RR infrastructure bond for rebuilding the system.
