Quest demand of freight doesn't stop.

[Riku]

In chapter 4 I have a steel industry in Beaumont. The quest says 12 steel is needed, also 12 steel is needed in New Orleans. Because the demand of 8 steel/week doesn't stop in Beaumont even after delivering the 12 steel, I can't deliver any steel to New Orleans.
This only happend to me in this chapter but i guess it can happen at any such quest.

[Rolf]

Hey Riku! :)
You have to have some demand for Steel in New Orleans first.
Then the Steel production in Beaumont has to produce more than is needed locally. If Beaumont uses up all the produced steel first, it cannot be stored in the Export Storage and therefore it cannot be exported to New Orleans.
Try to upgrade your Steel Factory.

[Riku]

That's correct but i would need to upgrade the steel factory atleast to lvl 4 and also be able to suppling it, by either buy and upping coal and iron mines or waiting until they upgrade themself. This leads to huge costs (also more profit later but I rather use the money else where) in either time or money.
Well my main point is that the demand by the quest does't stop after fulfilling it. Now that I've completed all quest of this part (the bridge was built/the construction building vanished) the demand stopped.