Actually, I wonder if anyone out there has tried making toll-roads where you pay more the more time you spend on the toll-road, as opposed to the more distance

Actually, I wonder if anyone out there has tried making toll-roads where you pay more the more time you spend on the toll-road, as opposed to the more distance you travel. That would certainly provide a nice economic signal to avoid congestion. Of course, you'd also need to install a large number of speed cameras, to stop the obvious method of gaming the system...