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By Chris Ingraham
In the remarkably clean and timely London Underground, a soothing voice over the loudspeakers advises travelers to “mind the gap.” Travelers on Bay Area trains could use something similar — if only they could hear it.
Most anyone who rides the region’s railways with any regularity will recognize the piercing screech immediately: it starts in the distance, with a rumbling down the tracks, and approaches the platform growing louder and louder, with a shrill discord that’s part screaming teakettle, part nails on a chalkboard. After years of complaints, policymakers in the Bay Area are finally beginning to investigate the awful sound’s cause, and its possible solutions.
While some might assume the noise results from whining brakes, the way a car’s brakes screech when the pads have worn thin, that’s a different, quieter problem. Otherwise, routine maintenance on the trains when they’re not in use could resolve the situation with relative convenience and ease.
The real problem is the rails. Over time, the wear and weight of heavy trains compresses the ballast beneath the tracks and between the ties. This results in bumpy, swerving rides — a related, but different problem. Noise issues begin more microscopically, as the wear of continual travel leaves the tracks nicked and kinked. These imperfections — the slight undulations, the tiny scars and ripples known as corrugation — create more friction with the train’s wheels and prevent their traveling as smoothly, and quietly, along their course.
Well, so how about oiling the tracks? Closer, but still not the solution. The San Francisco Bay Area Rapid Transit District (BART), for example, receives calls regularly from well-intentioned if somewhat exasperated customers, suggesting that someone oil the tracks to reduce the noise. These suggestions are right to identify the rails as the culprit, but added lubrication still won’t help for long.
Short of a whole-scale system redesign, the only way to mitigate the awful noise is to grind the rails. Unfortunately, rail grinding is expensive — and inconvenient. For over a decade, BART has been using the same old and inefficient grinder railcar, a truncated 600-horsepower diesel train of sorts that grinds the tracks to a smooth and polished consistency when operated slowly over a given route. This process is terrifically laborious. Of the entire 104-mile BART system, for instance, even the most expert rail grinders are able satisfactorily to grind only about one mile of track per night using the old railcar.
At the start of December, the Santa Clara Valley Transportation Authority (VTA) implemented a comprehensive rail-grinding project designed to reduce the noise in its rail system. After 16 days of concentrated, nightly work, the agency completed the project, but performed grinding on only 24.4 miles of its 42.2-mile network of rails.
Focusing on one small section of track at a time, operators work in pairs, one minding the controls, the other walking the grimy tracks. Each track has different imperfections requiring a specialized kind of grinding depending on the severity and type of its damage. The person on the tracks inspects the faults and suggests what is needed to the person in the cab, who then customizes a grinding pattern specifically suited to the proper reshaping. A computer linked to 20 grinding stones beneath the railcar develops a pattern of grinding to shave and smooth the top and sides of the rails. Like a barber who can cut off hair but can’t put it back on, rail grinders take care not to grind too much, lest the rails become too thin and need to be replaced entirely. The different imperfections in curved rails and straight rails make the task understandably difficult. Grinders rely on instinct and a trained eye, but sometimes require 20 or more passes and grinding patterns along a single stretch of track to finish the job.
In 2007, BART ordered the construction of a new, state-of-the-art grinder railcar, “a $4 million muffler,” which they hoped would take away some of the guesswork involved in successful rail grinding, while also improving the efficiency and quality of their task. Because the BART system uses tracks that are 9.5 inches wider than the standard American track, however, the new railcar needed to be custom made, and took some time to arrive. Now it’s here.
Even so, there remains the logistical issue of when to operate the grinder car. Because of the task’s slow, painstaking nature, it’s unfeasible to work at all during the day, while passenger trains are still running. VTA’s rail grinding project worked exclusively at night, and BART similarly sends track maintenance crews to work only during the brief nighttime window from 1 to 4 a.m. when the passenger trains have stopped for the day. Those who complain that BART doesn’t operate a full 24-hour schedule, as the New York MTA does, may not realize that track maintenance is the primary reason the system shuts down at all.
The Federal Railroad Administration and California Public Utilities Commission mandate routine maintenance for the safety of all railways. Noise problems, which are regarded as a public nuisance rather than a safety concern, are not as strictly regulated. Maintenance conducted by BART, VTA, and Caltrain (which also has a noise problem, albeit a less severe one) already exceed the standards required by law. Improvements to the noise problem stem largely from public complaints, and from the desire of transit officials to provide a better, more user-friendly service. Each system has a publicly elected or appointed board of directors in charge of maintenance decisions. They conduct regular meetings open to the public.
Currently, BART officials are focusing on fixing particularly noisy areas in the Transbay Tube, and at the entrance to Walnut Creek and Daly City. Although no areas are unsusceptible, some tracks are more damaged than others, perhaps because of heavier, more frequent use. The dinged tracks, however, aren’t the only contributing factor to the noise. Acoustic environment also matters. The Transbay Tube, for instance, creates an echo chamber for the noise to amplify and worsen. Outside, on the other hand, in areas where trains travel elevated through relatively open spaces, the noise has an opportunity to dissipate without being contained and increased by nearby walls or structures. It’s in the more congested, urban areas outside, and in less-than-cavernous underground stations, that the noise is most prone to reach extremes. Ultimately, though, all trains are noisy. It’s the change in pitch, caused by corrugation of the rails, that makes for such an earsplitting noise. Maybe until the new grinders make some progress — they are still relatively new and unused — BART will consider a more British slogan: “Mind your ears.”