I flew my drone over a nearby Seattle rail yard where there are always several locomotives idling, specifically in this section. This week I saw at least a dozen, and I wondered how they justify burning all that fuel. There are a lot of reasons, I found out, from mundane human nature to esoteric engine trivia.
From a 2004 thread of railway enthusiasts and engineers:
Problems restarting:
"Supposed to be shut down if not used within an hour. However, sometimes it is easier to waste fuel than have to call out a mechanic if the unit doesn't start."
To prevent water ingress through failing gaskets that would ruin the motor with a hydraulic lock (due to the incompressibility of water.)
"problem is the chance of water leaks between head and liner when the engine cools to ambient temp. This [has] required the precaution of opening cylinder test cocks and cranking the engine for a "blow down" check for water above the pistons. Such water would produce a hydraulic lock and break or bend something if the engine were cranked."
Computer problems:
"problems when they are restarted cold. Batteries can go dead and computers simply fail to reset."
Doesn't have "auto shutoff" installed:
"at BC Rail we have "auto start" on our newer and some older GE's, if the unit doesn't move for 20 minutes it shuts down, and restarts when the reverser is moved fwd or rev, or air pressure on main resevoir falls below X number of pounds, battery charge falls, engine block temp drops below certain temp or outside temp drops below 5 degrees centigrade. Works great and saves fuel, and I have never experienced a unit that will not start in "auto start" mode"
Low-grade fuel makes starting difficult:
"Properly set-up diesels when warm and running can tolerate some pretty cruddy fuel, but can be really intolerant when cold."
For conductor comfort:
"...overide of the shutdown on the lead unit so the air conditioning or heater keeps working."
To "save fuel:"
Most diesels are amazingly stingy fuel consumers at idle. At start-up they are pretty wasteful.
Management changes their mind about where the locomotive is going:
"power desk has already changed its mind a dozen different times on where and when it is going"
Above from a discussion thread.
Efficiency/(laziness?):
"Lengthy process to start...easier and faster for the incoming team to have it already running."
[They carry 5200 gallons when full, and burn 3-5 gallons per hour when idling.]
Organizational inconvenience:
"The problem is if it doesn't start. Then you have to call mechanical and wait for them to arrive. Nobody moves fast."
Lack of auxiliary engine:
"In Europe locomotives shut down but run a smaller engine that keeps the main engine warm and fully charged." [Later post disputes this]
Prevent freezing:
Locomotives use water instead of antifreeze to save cost (and prevent toxic spills;) even a remote chance of them freezing and blowing their temperature plug would be a huge hassle. [A later post mentions they will prophylactically dump their coolant through the "guru valve" at temperatures well above freezing, 40⁰F, to prevent engine damage.]
Difficult to restart:
Some locomotives use an air-pressure reservoir to restart; if this loses pressure they can't be restarted without outside help.
Slow boring restart:
Locomotive computer systems can take 15 minutes to boot.
Wear and tear:
"more wear and tear on the engine to restart than to just keep it running." [hard to believe]
Reddit thread.
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