New, stainless steel-capped aluminum third rail segments stacked in a warehouse.
A key a part of BART’s Measure RR rebuilding work is renewing energy infrastructure, a serious improve that can enhance the rider expertise by better reliability and fewer down time for repairs.
Together with cable and traction energy substation substitute, a part of the job is changing sections of third rail, the electrified rail that powers BART trains.
Stacked excessive in a chock-full storage warehouse are stainless steel-capped, aluminum third rail segments that will probably be extra environment friendly and economical. The brand new rail is half the load of the outdated and conducts electrical energy higher.
Which means simpler and sooner set up, as a result of the outdated rail weighed in at 27 kilos per foot or 810 kilos for a typical 30-foot section or “stick,” greater than twice the load of the brand new rail. It takes many staff to deal with such a heavy load, and the outdated rail can also be six instances stiffer than the brand new, making it powerful to place good. With the brand new rail, BART can do repairs extra rapidly, requiring much less down time and inconvenience.
Shut-up element of the brand new third rail that’s stacked in a warehouse ready for use.
The warehouse holds some 2,400 sticks of latest rail, at 12 kilos per foot, or 360 kilos per stick. That’s gentle sufficient to require far fewer staff to deal with. There’s a thick aluminum bar to conduct electrical energy, lined by a troublesome stainless-steel cap for resistance to the numerous iron paddles from prepare vehicles that slide throughout its prime, transferring energy to the prepare.
“Third rail is a vital asset for reliability of the facility system and steady prepare operation,” mentioned Myat San, BART’s Group Supervisor for Energy and Mechanical Engineering. “The helpful life of those third rail segments is about 20 years. As they age, effectivity and efficiency will probably be impacted.”
Again within the 1960s and 1970s, Kaiser Aluminum (not in enterprise) equipped all of BART’s third rail for the core system.
Outdated Kaiser Aluminum rail, previous its helpful life, is put right into a scrap pile for elimination.
There have been two kinds, an everyday one at four micro-ohms per foot (an ohm is a typical measure resistance) and a extra conductive model identified colloquially as “double-stuff Oreo” at 2 micro-ohms per foot. The extra conductive one was significantly costlier and utilized in areas with lengthy distances between traction energy substations.
The unique third rail was made by standing 30-foot metal I-beams vertically in molds, and pouring in molten aluminum for a powerful bond. It was symmetrical prime and backside, so when the tops wore out after about 20 years of use, BART electricians merely flipped them to make use of the opposite aspect. Ultimately each side would put on out and require third rail substitute.
By round 1990, with a lot of the third rail in high-wear areas on the finish of its helpful life and with no extra Kaiser Aluminum to supply new rail, one other producer supplied for core system replacements, in addition to for brand new extensions to the BART system corresponding to to San Francisco Worldwide Airport. This rail is the heavier, much less conductive rail in a lot of the system in the present day.
A corroded, weather-exposed rail cross-section, left, and a pristine pattern.
BART additionally determined to make all new third rail the thicker aluminum 2 micro-ohm/ft. model—the double-stuff Oreo variety — to cut back voltage drops and enhance prepare efficiency between substations. Third rail voltage has direct influence on prepare efficiency, and thus you will need to preserve it at acceptable ranges.
A number of years in the past BART examined a brand new, stainless-capped aluminum third rail product that supplied many benefits, and check sections have been put in south of Bay Truthful Station to see the way it carried out. After profitable exams, BART is transferring ahead to put in it systemwide, changing legacy four micro-ohm rail with the extra economical, extra conductive, lighter and extra versatile new rail. That’s excellent news for passengers, who can count on a smoother, extra dependable trip from the brand new third rail, the spine of energy for the entire BART system.
“The Measure RR work we’re doing to interchange substations, transformers, third rail and extra, is about reliability and a greater expertise for BART’s riders,” San mentioned.
BART District voters in 2016 permitted the Measure RR infrastructure bond for rebuilding the system. For extra data, go to our Measure RR rebuilding web site.