Subway Brake Dust

https://www.theguardian.com/environment ... hington-dc

Tiny airborne particles, probably thrown up by train brakes or the friction between train wheels and rails, are rife in the 71 underground stations sampled by researchers during morning and evening rush hours in Boston, New York City, Philadelphia and Washington DC, the cities that contain the bulk of subway systems in the US.

The levels of these tiny specks of pollution, called PM2.5, were well above nationally determined safe daily levels of 35 micrograms per cubic meter in each of the cities. New York’s Metropolitan Transit Authority (MTA) system had 251 micrograms per cubic meter, followed by Washington DC with 145 micrograms per cubic meter. Philadelphia was, comparatively, the cleanest system but still breached the limit beyond which serious health hazards are risked.

Now what do do about it?

The subway, after a century of usage, is thoroughly impregnated with the fine dust from brake shoes, etc.

For example do we apply a layer of lacquer over the entire tunnel wall and ceiling surface to seal (encapsulate) the dust somewhat adhering there?

Do we need to remove all of the track ballast and replace it with new? (Then bury the old ballast in a hazmat dump.)

How about running HEPA air filtering machines continuously to remove the dust from the atmosphere?

Under-platform vents to suck the particles down and away from the passengers might work.

I worked in the subway for decades. How am I not dead yet?

Disney Guy wrote: ↑Sun Feb 21, 2021 7:56 pm Do we need to remove all of the track ballast and replace it with new? (Then bury the old ballast in a hazmat dump.)

The only tunnel areas SEPTA has with ballast that I know of is a small amount of track near 15th Street in the trolley tunnel and I think Suburban Station to the portal might be ballasted?

Probably the best solution to kill this and several other birds with the same stone is platform edge doors.

WashingtonPark wrote: ↑Mon Feb 22, 2021 5:17 pm I worked in the subway for decades. How am I not dead yet?

You are. We forgot to inform you of this development.

SCB2525 wrote: ↑Mon Feb 22, 2021 8:29 pmThe only tunnel areas SEPTA has with ballast that I know of is a small amount of track near 15th Street in the trolley tunnel and I think Suburban Station to the portal might be ballasted?

The Tunnel on the Market-Frankford Line is ballasted from the eastern portal to 2nd Street.

Didn't SEPTA clean off the tunnel walls and ceiling of the brake dust because it was clogging the A/C vents on the then-new B-IV cars?

MattW wrote:Under-platform vents to suck the particles down and away from the passengers might work.

Improved ventilation in general is probably the most economical fix.

How much do MFL and BSL cars rely on friction brakes, vs dynamic brakes? Modern motor controls could essentially use the motors for propulsion and braking, all the way down to zero speed, leaving friction brakes for emergencies and parking. I expect we won't see this until the next generation of cars are in service, sometime in the 22nd century...