Node:New load/unload time calculation, Next:Mammoth Trains, Previous:Longer Stations/More Platforms, Up:The Patches
loadtime, q
(Note that this switch has been mostly superceded by the gradual loading feature, see Gradual Loading.)
In the original algorithm used to calculate how much time a trains spends in getting loaded/unloaded, there are two major bugs.
First, while loading time depends only on the amount of cargo, unloading depends on the type of cargo as well. Passengers will be unloaded instantly, while valuables will take forever. This does not make sense, it must be a bug.
Second, this time is multiplied by the number of cars sticking out of the station. If there are four cars sticking out, you'd have to wait five times as long, which doesn't make any sense either.
In this improved calculation, unloading time is again based on the amount of cargo and takes the same time as loading it. The bigger change though, is that the program assumes that for example a length four station can serve up to eight cars at the same time. This would mean that the time it takes to load/unload two cars is the same as for four or eight cars. This makes sense, because why would you want to build a large station if it can't effectively handle more than one car at the same time?
Also, the problem with cars sticking out is alleviated in two ways. The reasonable assumption behind them is the following: the train enters the station and gets as many cars loaded/unloaded as possible in one go. The engine will in most cases not be a part of this and can be ignored because it doesn't carry any cargo. If not all cars were able to fit in the station, the train will move the next set of cars in and have those unloaded. This will continue until the train is done.
A short summary:
To make it even clearer, here is a list for a length three station which can handle up to six cars at the same time. The engine is assumed not to be a cargocarrying engine:
Train length  Load/unload time (arbitrary units)

Eng.+1 car  1

Eng.+5 cars  1

Eng.+6 cars  1

Eng.+7 cars  2

Eng.+11 cars  2

Eng.+12 cars  2

Eng.+13 cars  3

Eng.+18 cars  3

Eng.+19 cars  4

and so on...

I find this to be a very reasonable calculation that makes sense and is realistic. If you don't, then you can always turn it off.
The unit time depends only on the average amount of cargo in each car. For example, if all cars are only half full (on average), it will only take half as much time.
However, the time it takes now for one single car is longer than previously. This switch was not meant to speed up loading/unloading but rather make it more sensible. "1" load time here is approximately the time it previously took to load six to eight cars.