5 ms·

6.5 hours for 300km sounds very slow. Is that because it's only a single track, and you lose a lot of time when passing oncoming trains? Or is the track not str

6.5 hours for 300km sounds very slow. Is that because it's only a single track, and you lose a lot of time when passing oncoming trains? Or is the track not straight enough for fast trains?

usrusr 3y ago
Why optimize for latency when throughout is your single dominatant metric? And with braking distances being the limiting factor of all train signaling schemes, you might even find yourself able to increase throughput by going slower. (not necessarily of course, but train signaling schemes are ... complicated)
ianburrell 3y ago
Freight trains are almost never fast trains. It isn't worth the extra energy for saving hours for containers that have been in transit for days. The rehabilitation increased the speed from 12mph to 43mph. They are planning passenger train that can reach 50mph. So that is probably limit to the railroad.
aksss 3y ago
I don’t think cargo trains ever go “fast”. But it is slower than normal in the US anyways. I think in US max speed for cargo is like 50 mph / ~75 kph, and this train is going along at 46 kph assuming constant motion. In reality, it’s fast in some segments, dramatically slower in older segments. According to Wikipedia, it’s an old line that has speed limitations in some areas of 20 kph. Addressing these limitations is a substantial part of the rehabilitation project, aiming to get the speed from 20 kph up to 70 kph. https://en.m.wikipedia.org/wiki/Interoceanic_Corridor_of_the_Isthmus_of_Tehuantepec https://en.m.wikipedia.org/wiki/Interoceanic_Corridor_of_the... “the rehabilitation is reportedly expected to result in a speed increase for trains using the railway, from 20 kilometres per hour (12 mph) to 70 km/h (43 mph) for cargo trains, and of up to 80 km/h (50 mph) for passenger trains”
- bluGill 3y ago
  Depends on the cargo. Mail and fresh food goes fast as time matters. Most other freight would prefer to save money with slower speeds.
  - aksss 3y ago
    The weight and speed limits are a regulatory matter in the US, as there's a safety factor at play. Derailments of cargo tend to be... messy affairs.
    - bluGill 2y ago
      Freight travels at many different speeds. There are many tracks in the US that are speed limited to 30mph or less because they have not maintained the tracks to higher standard, even though there are other freight tracks where trains move at 60+mph.
      - aksss 2y ago
        Yep, sometimes there are hills that also cause trains to go faster or slower depending on the incline. Fascinating world out there. Speeds are regulated.. Here's some reading: https://en.wikipedia.org/wiki/Rail_speed_limits_in_the_United_States#:~:text=Signal%20speeds,-Learn%20more&text=Federal%20regulators%20limit%20the%20speed,(See%20dark%20territory https://en.wikipedia.org/wiki/Rail_speed_limits_in_the_Unite....)
deleted 3y ago
[deleted]

6.5 hours for 300km sounds very slow. Is that because it's only a single track, and you lose a lot of time when passing oncoming trains? Or is the track not straight enough for fast trains?

usrusr 3y ago

Why optimize for latency when throughout is your single dominatant metric? And with braking distances being the limiting factor of all train signaling schemes, you might even find yourself able to increase throughput by going slower. (not necessarily of course, but train signaling schemes are ... complicated)

ianburrell 3y ago

Freight trains are almost never fast trains. It isn't worth the extra energy for saving hours for containers that have been in transit for days. The rehabilitation increased the speed from 12mph to 43mph. They are planning passenger train that can reach 50mph. So that is probably limit to the railroad.

aksss 3y ago

I don’t think cargo trains ever go “fast”. But it is slower than normal in the US anyways. I think in US max speed for cargo is like 50 mph / ~75 kph, and this train is going along at 46 kph assuming constant motion. In reality, it’s fast in some segments, dramatically slower in older segments. According to Wikipedia, it’s an old line that has speed limitations in some areas of 20 kph. Addressing these limitations is a substantial part of the rehabilitation project, aiming to get the speed from 20 kph up to 70 kph. https://en.m.wikipedia.org/wiki/Interoceanic_Corridor_of_the_Isthmus_of_Tehuantepec https://en.m.wikipedia.org/wiki/Interoceanic_Corridor_of_the... “the rehabilitation is reportedly expected to result in a speed increase for trains using the railway, from 20 kilometres per hour (12 mph) to 70 km/h (43 mph) for cargo trains, and of up to 80 km/h (50 mph) for passenger trains”

bluGill 3y ago
Depends on the cargo. Mail and fresh food goes fast as time matters. Most other freight would prefer to save money with slower speeds.
- aksss 3y ago
  The weight and speed limits are a regulatory matter in the US, as there's a safety factor at play. Derailments of cargo tend to be... messy affairs.
  - bluGill 2y ago
    Freight travels at many different speeds. There are many tracks in the US that are speed limited to 30mph or less because they have not maintained the tracks to higher standard, even though there are other freight tracks where trains move at 60+mph.
    - aksss 2y ago
      Yep, sometimes there are hills that also cause trains to go faster or slower depending on the incline. Fascinating world out there. Speeds are regulated.. Here's some reading: https://en.wikipedia.org/wiki/Rail_speed_limits_in_the_United_States#:~:text=Signal%20speeds,-Learn%20more&text=Federal%20regulators%20limit%20the%20speed,(See%20dark%20territory https://en.wikipedia.org/wiki/Rail_speed_limits_in_the_Unite....)

deleted 3y ago

[deleted]