Industry production efficiency (or How to work out how much steel from iron ore?)

Question

In OpenTTD - I've noticed that delivering 120 tonnes of iron ore (for example) does not convert into 120 tonnes of steel. This appears to hold for other manufacturing process in the game. I suppose this is reasonable, as there is probably inefficiencies.

I want to be able to accurately set the length of trains taking steel away so they are immediately fully loaded and ready to roll once the raw material is provided (so, 120 tonnes of iron ore rolls in, and the steel train immediately rolls out).

Is there are simple ratio involved here - is it predictable? Or are there other factors involved that makes this impossible.

My only other strategy, that I'm employing now, is make a bit of a guess and then removed unfilled wagons after the first delivery of raw materials.

Answer 1

120 tons of iron ore does in fact convert into 120 tons of steel. The amount that gets delivered to your station, however, will almost always be less than that.

In the common situation where there is only one station picking up cargo from an industry, this is easy to calculate: the amount delivered is the amount produced times your station rating expressed as a decimal (eg. 120 tons of steel * .78 station rating = 94 tons of steel to transport).

The multi-station situation is more complicated. First, only the two highest-rated stations that could pick up cargo from that industry matter. According to the OpenTTD wiki, the higher-rated of the two stations will get (rating of station 1)/(rating of station 1 + (rating of station 2 / 2)) * 100% of the available cargo, while station 2 will get a percent of the remainder equal to its rating. If both stations are rated equally, one of them will be picked arbitrarily to be considered the higher-rated one.