Hacker Remix

Detrimental Decibels: A Study of Noise Levels in Vancouver's SkyTrain System (2022)

42 points by luu 7 days ago | 21 comments

Anechoic 6 days ago

The paper basically reinforces one of the tenets of transit noise and vibration analyses: if you don't maintain your system (specifically wheels and rails in the case of noise), things tend to get louder over time. BCRTC knows this [0] and they're working on it. As with all things, it's about time and money, but they are trying to be proactive with vehicle and track maintenance via rail grinding and complaint tracking.

[0] https://archive.wheel-rail-seminars.com/archives/2022/rt-pap...

guardiangod 6 days ago

The rail grinding noise of those Mark 1 Skytrain cars are really something. They literally made my ears hurt. For reference New York's subway rail noise never made my ears hurt that much.

The explanation I read online is that Translink (the transport authority) lost one of the 2 rail grinders they contracted, and had to buy a grinder for use. So for a few years, while waiting for the grinder to arrive, the rails were not getting the regular grinding needed that'd lessen the wheels-on-rail noise.

An unverified rumor I heard was that Translink cheaped out and bought a batch of substandard rails that are softer than needed. This means the rails wear out and become out of spec faster. The issue was compounded by the fact that the softer rails were used to replace a large portions of routes with sharp curves.

The rolling stocks use linear induction propulsion, which means there is no electric motor on the train. The trains are very light as a result and require different maintenance.

xattt 6 days ago

> LIM

A few thoughts:

The downside to LIMs is that they have ann unexpected derailment/failure mode (1), as manifested by the 2023 SRT derailment.

Briefly, the magnetic repulsion/attraction forces of an accelerating train caused a section of the reaction rail to catch on the train, which catapulted a train car.

I’ll also mention used to live near the SRT. They were still great and quirky around the 10 year mark. However, the Mark Is didn’t age well. They just got louder and louder.

They also became more and more susceptible to severe weather, to the point they were run in manual mode (versus ATO) with every snow storm.

(1) https://stevemunro.ca/2024/01/31/the-scarborough-rt-derailme...

rob74 6 days ago

Grinding the rails only helps against roughness of the upper surface of the rail (which causes a "roaring" noise - https://en.wikipedia.org/wiki/Railgrinder#Rail_corrugation). The most annoying noise in my experience is the screeching noise when going around curves (or on badly maintained straight tracks) - this can best be solved by using flange lubrication (https://centrallubrication.com/en/lubrication-techniques/whe...).

Doxin 4 days ago

On a well designed track the flanges should not ever rub. Of course with light rail you'll sometimes run into a problem where a curve needs to be tighter than can be done without flange rubbing. The Amsterdam tramways have a couple places like that and the noise is godawful.

shiroiushi 6 days ago

>The rolling stocks use linear induction propulsion, which means there is no electric motor on the train.

This sentence makes no sense at all. A linear induction motor is a type of electric motor.

wesapien 6 days ago

I agree. From what I can recall, the Expo line is just as loud as riding in a Tokyo subway. Good thing I always have an in-ear or NC headphone with me when I travel.

PeterStuer 6 days ago

If that is passive hearing protection through isolation you are probably good. But do the 'active' NC headphones actualy prevent hearing damage?

martinpw 6 days ago

> Studies in Toronto and New York have shown that sound intensity peaks in their respective transit systems exceed medically-safe sound level limits

I still remember the shrieking rail noise when the subway in Toronto took the tight corners into and out of Union Station, and the same for the streetcar that went south from there to the waterfront. Always felt like that gave me some permanent hearing damage since I often didn't cover my ears quickly enough. Have not been there for 15 years though - is it still like that?

Patrick_Devine 6 days ago

When Skytrain first came out it was touted about how quiet it was vs. other metro systems. [1] The problem (as others have pointed out) is just the Mark I trains are 40 years old and the maintenance hasn't kept up with the track and the wheels. Things wear out.

[1] https://youtu.be/pTsSXdSjU1I?t=455

bpye 6 days ago

Reminds me of how the London Underground was advertised as being cooler during the summer [0].

[0] - https://www.ltmuseum.co.uk/collections/collections-online/po...