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

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

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42 pointsluu21 comments

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...

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.

> 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...

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.

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

>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.

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...).

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.

> 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?

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

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...

I don't have anything particularly enlightening to say but I once visited an apartment that was within a few meters of the skytrain track. Thing was loud as can be and made me nope out very quickly. The place wasn't even cheaper than equivalent (minus deafening noise) options, maybe they were hoping to find someone who was already deaf.

Insanely bad thing is that because of exclusionary zoning and the political need to protect single family home areas at all cost, the city continues to push more and more residential homes into areas right next to the skytrain. Terrible.

This does depend somewhat on the city - for context Metro Vancouver isn’t amalgamated. Burnaby has been particularly guilty of this…

And then you have Montreal with their very quiet rubber wheeled metro system. https://www.mcgill.ca/oss/article/student-contributors-techn...

The problem with the Vancouver system is the combination of it being above ground and noisy. Ideally, you want to build density directly beside the tracks. That said, I lived near the tracks for a few years and although we could hear it, it wasn't that bad. We were fairly high up and had good windows.

However this study is about the impact of the noise on passengers, not people living beside the tracks. For passengers, I think a tunnel (which reflects the noise back) is worse than an above-ground track. Of course, for both avoiding tight curves during planning and good track maintenance help a lot...

The article you linked also mentions some of the disadvantages of rubber-tire metros:

> Rubber tires wear faster and must be replaced more frequently, meaning more waste. Trains on the Paris Metro – which pioneered the use of rubber tires and inspired Montreal’s design -- can run for 4,325,917 km for every $1 million in maintenance; Toronto’s steel wheeled trains can go for 8,991,405 km-- more than double. Montreal’s Metro requires approximately 2900 new tires every year – that’s a lot of old tires being discarded. When these tires break down, they also create airborne particulate matter that can remain in the environment for years, contributing to air pollution.

The friction between rubber and concrete is greater than between a steel wheel and steel tracks. This means that more energy is required to push Montreal’s cars forward than Toronto’s

London Underground destroys all other transit on the planet when it comes to noise, and ironically, it's not even the trains themselves, it's the effing speakers

MIND THE GAP

louder than an Iron Maiden concert, it's unbearable and unnecessary, no idea why they don't turn that shit down

Well, the trains are still quite bad on their own. Especially the deep lines.

At least the lights stay on most of the time these days.

The worst is the squeal of the wheels against the track in the semicircular tunnel from Waterfront to Burrard (or in the reverse direction), in the summer, when people leave windows open. I think this is due to the axles being solid: no differential spin.

I'd wear noise canceling earbuds or earplugs if I didn't care about keeping track of my surroundings. Hearing loss isn't exactly top of the mind when riding BART :)

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