when travel time is calculated the way i think it is, then you should not be above the 20 minute window. “Goods” and “Oil” are treated seperatly and everyone should have its own timeframe.
to solve your problem you should check other things first.
how long is this setup running?
how much is the demand of that city?
does the city get other “Goods” from another place?
peronly, i’ve never used trains for industry duty. i only used trucks. maybe there is a problem when you are useing two diffrend transport typs for one production chain.