Get missing construction elements

[manpapper]

It should be great if there was a way to get the number of missing construction elements from the roboport or something else with green/red circuit.

For exemple if we have two bases way to far to link them with roboport or the way to go is full of biters.
There is no way to connect the two bases with roboports so if one base need something the other one need we this feature the train will automatically send the require ammount.