What could a fully implemented ADS look like?
The roads and streets would be completely different than anything we have now, and would look more like something from the early 20th century than anything we are familiar now.
With a fully automated system there would no longer be multi-directional traffic lights to control traffic flow. There would be some sort of traffic control bollard or pole, perhaps situated in the middle of the intersection, but what you see now in 2012 in terms of traffic signals would not be needed. You would still see pedestrian signals though.
The painted lines on the roads that tell drivers where the lanes are would no longer be needed. The function of the painted lines would be taken over by a combination of GPS, road side control systems, and in-vehicle sensors. Once again, you would probably find painted lines for pedestrians at major intersections.
Street lighting would be dramatically affected. On urban highways lighting would all but disappear. The cars don't need light at all, and the people in the cars don't need it because they aren't driving. Perhaps there would be some sort of lighting that would come on in the case of accidents of whatever description, e.g. animals or people on the road, debris falling of bridges or other vehicles, and that lighting would be for the people who need to deal with whatever the incident is.
On residential and open access urban roads the lighting would change to pedestrian level street lighting, as there would be no need for light for drivers to navigate their cars.
Road signs that currently tell drivers to expect winding roads, that the bridge ices, or that the Main Street exit is in four kilometers would for the most part disappear. Indeed, there might be no informational signs at all on closed access highways and roads. Why put them up when you can ask your car what your location is, or where the nearest rest stop is? Perhaps there would be tourist attraction type signs on the roads for people to take that impulse to see the local attractions as they drive along.
Road rage would be, mostly, a thing of the past. One of the main causes of road rage is people driving foolishly in the opinion of another driver near them. When no one is driving, when all the rules of the road are being followed, and no one around you is driving foolishly, why get angry?
Accidents would be rare. Car computers do not get distracted by the pretty girl or cute guy on the sidewalk. They don't get drunk, or fall asleep at the wheel. They don't drive too fast for the conditions, or too slowly on the highway. Sadly, I suspect that when accidents did happen they would be bad because it would mean the failure of the individual car computer or of the local ADS node.
The design of cars themselves would change radically. Imagine a car that had no steering wheel. Consider, you have grown up never having driven a car. You are thirty years old, speeding down the highway at 100km/hour, and the ADS system goes down. Even if you have a steering wheel, a brake, and a gas pedal, what would you do? Imagine the very first time you drove a car. How nervous were you then? Now imagine how you would have felt if you were driving a car for the first time, in an emergency situation, on a closed access highway. What will you do? That scenario is why steering wheels will be removed from cars, along with the gas pedal , and the brake - people will no longer know how to use them.
If a car has no steering wheel, then what does that do to the interior design of the car? Do we all really need to face the same direction is a standard passenger car? Why not have the front seats face the back seats, and put a table between them? You could eat, play games, watch movies, or work, and in more comfort than we do now. Perhaps the interior of the car could be converted into a surround movie experience, on an as needed basis. Much of the current dashboard would be eliminated in car with no steering wheel, which would free up space for the above mentioned rearrangement of the seating.
What about exterior and interior lighting? Exterior lighting on a car serves three purposes, one is to allow the driver to see the road in dark conditions, the second is to allow pedestrians to see the car, and finally to signal intention to other drivers and pedestrians. With an automated system the headlights would be, not eliminated, but dimmed significantly, giving enough light to show location to pedestrians, but not enough to illuminate for any great distance. Signal lights would remain so pedestrians could know what a car was going to do.
Interior lighting could be significantly improved. The reduced light levels in cars at night are so the driver can see out the windows. When there are no drivers, then the light levels in the cabin of the car can be made comfortably bright enough for people to read without impacting the operation of the car.
Cars would drive by in tightly packed trains (at least in good weather conditions), starting and stopping as a unit, which might look rather interesting.
Curiously enough, there might actually be be less road construction. Currently roads are built on a scale that allows for human interactions, and reaction times. If computers are controlling the cars then the current road system should be able to handle significantly more traffic, how much would depend on the road, but I would guess at least 25% more cars. The other impact that would reduce road construction, would be that overweight vehicles (trucks) would not be able to drive on roads they were not approved for, which reduces the wear on the roadbed, and so the need for maintenance on the road.
There are of course more items I could mention, but I will leave them for other posts.