I was working on Sea Going Vessels that ran the Delaware River on a regular schedule back in the 90's. They were just starting to use Chart Readers with DGPS (Differential Global Positioning System) which was supposed to be very accurate. The idea was to have Chart over lay used injunction with the DGPS. Some Captains thought this was a great idea and would allow them to transit in very low visibility.
On one trip I just happened to be in the Wheel House (I was normally always down below as I was Chief Engineer) while we were northbound and looked at the Chart System. I was a little more than surprised to see it showing us Northbound on 495 (might have been I-95), which was about a mile or so to the left of where we actually were. Needless to say the Company had to come out and tell them NOT to use it for Navigation.
Fast forward to 2005 (when I retired) we were running Tampa Bay on vessels loaded to max draft (max depth of water in the channel) and using a system designed just for use in Tampa Bay. According to my Captain (who was a Licensed Pilot for Tampa Bay) this system was so accurate that it would show it you were not in the center of the Channel by as much as a couple of feet.
Even with him knowing how accurate this system was, he would never sail knowing that he would have to trust it. There were times when Fog set in causing visibility to drop to next to nothing and this system allowed him to safely to transit the channel.
I am sure that sooner or later they will have a system that will work but until ALL vehicles are equipped with the same type of system (and the can talk to each other) I do not see this being used nation wide. There are just way to many variables (distracted drivers, road debris, large trucks / RVs) for any system to read in milliseconds for it to work.
