What might driving un an automated highway he like? The answer depends on what kind of system is ultimately adopted. Two distinct types are un the drawing board. The first is a special-purpose lane system, in which certain lanes are reserved for automated vehicles. The second is a mixed traffic system: fully automated vehicles would share the road with partially automated m' manually driven cars. A special-purpose Jane sys tem would require more extensive physical modifications to existing high ways, hut it promises the greatest gains in freeway capacity. Under either scheme, the driver would specify the desired destination, furnishing this information to a computer in the car at the beginning of the trip or perhaps just before reaching tile automated highway. If a mixed traffic system way was in place, automated driving could begin whenever the driver was on suitably equipped roads. If special-purpose lanes were available, the car could enter them and join existing traffic in two different ways. One method would use a special onramp. As the driver approached tile point of entry for tile highway, devices installed on the roadside would electronically cheek the vehicle to determine its destination and to ascertain it had the proper automation equipment in good working order. Assuming it passed such tests, the driver would then be guided through a gate and toward an automated lane. In this ease, the transition from manual to automated control would take place on the en trance ramp. An alternative technique could employ conventional lanes, which would be shared by automated and regular vehicles. The driver would steer onto the highway and move in normal fashion to a 'transition' lane. The vehicle would then shift trader computer control onto a lane re served for automated traffic. (The limitation of these lanes to automated traffic would, presumably, be well respected, because all trespassers could be swiftly identified by authorities. ) Either approach to joining a lane, of automated traffic would harmonize the, movement of newly entering vehicles with those already traveling. Automatic control here should allow for smooth merging, without the usual uncertainties rent potential for accidents. And once a vehicle had set tied into automated travel, the driver would be free to release the wheel, open the morning paper or just relax. We learn from the first paragraph that two systems of automated high ways______.