A key benefit of rail grinding is quieter train operations, both on straight and curved tracks. Rail grinding removes minute surface irregularities in the rail surface caused by normal train operations, allowing rail car wheels to more smoothly roll over the track, which in turn reduces noise generated by light rail vehicles.
Targeted for grinding this year is "embedded" trackway most commonly found at intersections or pedestrian malls. Embedded track is laid in concrete, rather than on ties. Affected by the upcoming work will be the embedded trackway between the Children's Discovery Museum Light Rail Station to just past Interstate 880 on North First Street and intersections from there to the Mountain View Light Rail Station. Minor amounts of rail grinding will also take place on VTA light rail tracks located in east and south San Jose and Campbell.
The grinding equipment is integrated into a rail car and is too large and slow moving to be used while regular passenger service is running so the work must be done during late night hours. The machine moves at a rate of approximately 1.5 miles per hour, although more than one pass of the grinder is generally required to reach an optimal track contour. Work at most locations will be finished in 20 to 40 minutes.
While the noise of the grinding is audible to someone located near the work, noise levels are required to be no greater than 85 decibels at 25 feet from the center of the track. This noise level is roughly equivalent to noise generated by a hair dryer or vacuum cleaner.