3 ms·

>Long term(as in multiple decades) we might want to switch maglev railways, as there is no friction to stir particles in the air from that. Is there a major en

by ginko 5y ago

>Long term(as in multiple decades) we might want to switch maglev railways, as there is no friction to stir particles in the air from that. Is there a major environmental/health problem with particulate from regular steel-on-steel railways? I would guess the iron particles don't travel very far due to their density and will mostly turn to harmless iron oxide.

mschuster91 5y ago
> Is there a major environmental/health problem with particulate from regular steel-on-steel railways? Yes, as only extremely modern passenger trains have regenerative or resistive electrical brakes and even they need to do the last few bits of the braking process with the old friction brakes since electrical braking doesn't need at low speed. Old trains, especially freight, still runs entirely on friction brakes - either metal or the new "silent brakes" that are a plastics composite. Additionally, you have environmental concerns from oil and lube, which is why you should never fucking ever re-use torn out wooden railway sleepers. They are drenched in immensely toxic anti-rotting agents to begin with, and seep up all the oil and other contaminants (e.g. feces from bypassing old trains without closed-loop toilets).
- bloak 5y ago
  I wouldn't necessarily carve salad servers out of old railway sleepers but I don't see what problems they'd cause if used for the edge of a flower bed. Remnants of human faeces that have been in the sun and the rain for a year seem a lot less frightening that the fresh cat and pigeon poo you'll find in almost any urban garden.
  - mschuster91 5y ago
    > I wouldn't necessarily carve salad servers out of old railway sleepers but I don't see what problems they'd cause if used for the edge of a flower bed. The anti-rot agents (and, in case your local railway does pesticide spraying to reduce weeds, these too) will leech out into your flower bed and kill it off.
- namibj 5y ago
  No, the modern inverter electric locomotives can break to zero with the motor just fine, they just lack a sensor to accurately measure speed and their motors take, at these ultra-low-speeds, a "desired torque" value, not a "desired RPM" value. You still want friction breaks to hold you in place once you've stopped, but there's no strict need to use them earlier. Yes, current controllers may not be intelligent enough, but that should be fixeable without changing the power electronics, and only replacing their controller.
  - mschuster91 5y ago
    Lot of the rolling stock is 40 years and older though, with new locos costing millions of dollars apiece it takes lots of time to modernize fleets. Europe still uses screw and hook/buffers for that reason, and it took well over a decade to mandate silent composite brakes.
    - namibj 5y ago
      Yeah, rolling stock is old. Also, in Germany the DB Class 120 locos (the first series-production 3-phase inverter electric locos) were retired between 2016 and 2020 (build during the 80's). Even the older non-inverter locos here use electro-dynamic brakes (afaik for economic/control reasons, as they are better than air for keeping speed during downhill sections under control), and the remaining ones will retire soon. The screw and hook/buffers issue is more due to the distributed ownership of the freight cars, and early issues with certification of adapters between UIC central couplers and screw+hook/buffers. Sure, there are situations where it's too steep to only brake the loco, but they aren't that common and adding some induction brakes to some of the heavier cars and preferentially using them shouldn't be particularly expensive. Sure, not cheap, but also not prohibitive for getting rid of friction breaks in the course of normal operation (well, some friction breaking may be needed from time to time to keep them in check and verify proper function.... but still a >90% reduction shouldn't be hard.
SideburnsOfDoom 5y ago
> Is there a major environmental/health problem with particulate from regular steel-on-steel railways? In tunnels, from "erosion from the wheels and brakes, and the rails", yes: https://www.wired.co.uk/article/london-tube-dust https://www.wired.co.uk/article/london-tube-dust

by ginko 5y ago

mschuster91 5y ago

> Is there a major environmental/health problem with particulate from regular steel-on-steel railways? Yes, as only extremely modern passenger trains have regenerative or resistive electrical brakes and even they need to do the last few bits of the braking process with the old friction brakes since electrical braking doesn't need at low speed. Old trains, especially freight, still runs entirely on friction brakes - either metal or the new "silent brakes" that are a plastics composite. Additionally, you have environmental concerns from oil and lube, which is why you should never fucking ever re-use torn out wooden railway sleepers. They are drenched in immensely toxic anti-rotting agents to begin with, and seep up all the oil and other contaminants (e.g. feces from bypassing old trains without closed-loop toilets).

bloak 5y ago
I wouldn't necessarily carve salad servers out of old railway sleepers but I don't see what problems they'd cause if used for the edge of a flower bed. Remnants of human faeces that have been in the sun and the rain for a year seem a lot less frightening that the fresh cat and pigeon poo you'll find in almost any urban garden.
- mschuster91 5y ago
  > I wouldn't necessarily carve salad servers out of old railway sleepers but I don't see what problems they'd cause if used for the edge of a flower bed. The anti-rot agents (and, in case your local railway does pesticide spraying to reduce weeds, these too) will leech out into your flower bed and kill it off.
namibj 5y ago
No, the modern inverter electric locomotives can break to zero with the motor just fine, they just lack a sensor to accurately measure speed and their motors take, at these ultra-low-speeds, a "desired torque" value, not a "desired RPM" value. You still want friction breaks to hold you in place once you've stopped, but there's no strict need to use them earlier. Yes, current controllers may not be intelligent enough, but that should be fixeable without changing the power electronics, and only replacing their controller.
- mschuster91 5y ago
  Lot of the rolling stock is 40 years and older though, with new locos costing millions of dollars apiece it takes lots of time to modernize fleets. Europe still uses screw and hook/buffers for that reason, and it took well over a decade to mandate silent composite brakes.
  - namibj 5y ago
    Yeah, rolling stock is old. Also, in Germany the DB Class 120 locos (the first series-production 3-phase inverter electric locos) were retired between 2016 and 2020 (build during the 80's). Even the older non-inverter locos here use electro-dynamic brakes (afaik for economic/control reasons, as they are better than air for keeping speed during downhill sections under control), and the remaining ones will retire soon. The screw and hook/buffers issue is more due to the distributed ownership of the freight cars, and early issues with certification of adapters between UIC central couplers and screw+hook/buffers. Sure, there are situations where it's too steep to only brake the loco, but they aren't that common and adding some induction brakes to some of the heavier cars and preferentially using them shouldn't be particularly expensive. Sure, not cheap, but also not prohibitive for getting rid of friction breaks in the course of normal operation (well, some friction breaking may be needed from time to time to keep them in check and verify proper function.... but still a >90% reduction shouldn't be hard.

SideburnsOfDoom 5y ago

> Is there a major environmental/health problem with particulate from regular steel-on-steel railways? In tunnels, from "erosion from the wheels and brakes, and the rails", yes: https://www.wired.co.uk/article/london-tube-dust https://www.wired.co.uk/article/london-tube-dust