As you can see all trucks got stuck to deliver materials to first storage, I thought this might work but seems they keep trying to go to first storage. I wish there was a way to help them…
You can use districts to tell concrete factories which storehouse they are allowed to deliver to.
The issue with districts is that all of the factories are in one district… 8 To be exact and the storage can not handle them
you can put half of your concrete factories in one district and the other half in the other. Each storehouse is also in a separate district.
Then you make the export rules to only allow delivery into the district with one storehouse 
I also think this is overcomplicated. Coming from thousands of hours of games like Factorio, I think the game should either remove the input limit from the storehouses, provide some way to upgrade their i/o capabilities or provide an easier way than districts to balance multiple factories to multiple storehouses. The current approach doesn’t really scale, I already built 10 concrete factories in the first half hour of my first playthrough and it took me forever to figure out how to really use all the produces concrete.
Yeah concrete feels like a pain to manage for traffic, but also a bit useless in my opinion once you reach a certain flow ( mid game ).
I’m not quite sure about this, are housing using concrete when it upgrades ? If so, I didn’t notice that.
It should be a good use case on how to spend those thousands of concrete stocks in my opinion, basically each house upgrades costs (x) concrete.