Fantastic job! Exceptionally faithful to the original and very fun! I have two suggestions having played most of the campaign.
The cargo carrier is presently useless in the face of the tunnel transport (not your fault of course, it was removed from the original game after all!) My suggestion would be to allow the cargo carrier to transport 4 or so miners if it isn't carrying a vehical.
The other suggestion is a variation on the dispense option from the tool store, have a button for transport vehicals (and possibly miners) that will cause them to run to a tool store you select and pick up a resource (or multiple for transports), they will not put the resource back at least for a few seconds (or possibly it could be locked to them with a toggle). This allows for easier loading of say, a small transport filled with studs, to be taken by a cargo carrier.
Again fantastic job! I hope this project gets to be everything you want it to be!