TransLink is looking for a contractor to provide a supply of rail dampers for use on problematic sections of the SkyTrain Expo Line where there is excessive track noise.
A request for proposal (RFP) was recently issued as the latest part of the years-long, multi-faceted noise mitigation project for the Expo Line.
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Rail dampers are sandwich-like rubber and steel devices affixed on both sides of steel rails to absorb some of the vibration energy that causes noise, and dissipate it as heat. By reducing vibrations, this also has the effect of reducing the wear and tear of the tracks.
The public transit authority is looking for a contractor that will design and produce dampers to Expo Line specifications. Dampers are being targeted for a length of 3.2 km of track.
The contractor will supply all materials, equipment, and tools necessary for SkyTrain maintenance crews to conduct the installation.
A 2018 study on the Expo Line’s excessive noise issues noted the option of considering dampers. At the time, dampers were deemed too expensive to install, but there were tests being conducted on parts of the system.
Other recommendations made by the study include replacing the aging softer rail steel installed on the original Expo Line sections with harder rail to prevent noise-emitting corrugation, but this could come with the tradeoff of quicker wear on the train wheels.
The installation of “friction modifiers” applied onto the tracks as a liquid or in the form of “sold sticks” pushed against the wheel treads was also noted as an option to reduce rail wear and slow down corrugation.
Better overall maintenance, especially of track switches, was identified as a key mitigation measure.
TransLink has been replacing significant sections of the Expo Line’s rails since 2018. The latest work targeting the section of track between Commercial-Broadway Station and Main Street-Science World Station includes 6.7 km of rail and 14,100 rail pads.
This work will begin March 2021 and last through Winter 2021/2022, taking place overnight from 10 pm to 4 am most days Sunday through Thursday. Some nighttime noise can be expected for periods of up to two weeks at a time as crews move along the tracks.
“Rather than making spot-fixes as we have in the past, we’re taking a proactive approach to replace rail and rail pads along specific segments of track all at once,” a TransLink spokesperson told Daily Hive Urbanized in an email.
The section of rails on the spans between VCC-Clark, Commercial-Broadway, and Nanaimo stations were identified by the study as the most problematic areas for excess noise. This area has the highest number of people potentially affected by “very high noise levels” both above 85 dBA and above 90 dBA, largely due to rough rails in high-speed sections of track, especially as trains cross switches.
Consultants indicate they have established a train passing noise goal of 75 dBA at residential facades with windows closed, which is “considered to be a reasonable balance between the adverse effects of noise and other benefits of rail transit systems to communities.”