Because of community annoyance near a Washington, D.C., Metro rail transit car maintenance yard, a comprehensive noise measurement and analysis program was implemented for the Washington Metropolitan Area Transit Authority (WMATA) to examine the wheel squeal generated as transit cars travelled around small-radius curves. Sound levels were measured near the track as well as at locations in the neighbourhood near the subject maintenance yard. Comparative measurements were also performed in two other nearly identical yards. In the absence of wheel squeal, train movements were almost undetectable outside the yard; hence, squeal elimination would satisfy community complaints and allow removal of an operations curfew. Water lubrication of the rails, found to be effective in eliminating squeal, was considered impractical for winter operations. Rail facing (a proprietary railhead treatment) was selected by WMATA as an experimental squeal control. Testing of the rail facing within 1 week of installation yielded a 23-dBA sound level reduction and the complete elimination of squeal. However, after about 3 months' service, a 14-dBA reduction with some squeal was observed; and after 6 months' service chronic squeal reappeared. This loss of effectiveness was ascribed to rapid contact point wear of the facing treatment.
Samenvatting