Automated Highway System with private cars driven automatically through guided pathway has a clear benefit of offering convenience, reducing door-to-door transit times and better utilization of the transportation system. Also with the precision of automation, we can do platooning and pack more cars onto the highway without reducing the speed of the traffic moving through the pathway.

Development of such an automated highway system is dependent on the development of reliable contact-free guidance and non-tethered control using wireless technologies. We propose that the use of radar based guidance with the strategic placement of reflectors along each side of the guided pathway providing "soft" non fixed guidance. With the development of low cost phased array beam-forming and beam-steering FMCW radars, it is possible to develop reliable on-vehicle radar based guidance system without compromising on the overall safety and reliability of the guidance system. Reflectors aid in improving the specificity of target detection and in improving the accuracy of range, relative velocity and azimuth determination of the target, which would be important for the assurance of reliability of the guidance system. The radar reflectors are easier to ruggedize for an all-weather highway application.

We also use platooning with an appropriate guidance law for homing and terminal guidance and stabilized rendezvous for a stable and reliable platoon formation. The platooning aids in reducing inter vehicle distances and increasing the capacity of the highway. Smaller cross section reflectors on the back of a lead vehicle in a platoon formation would also allow to reduce the following distance for the follower vehicles while improving the specificity of the radar and thereby reliability of the lateral guidance for following vehicle. The platooning guidance law handles the platoon formation, joining of new vehicles to the platoon and vehicles leaving the platoon. We use wireless links between infrastructure to vehicle and vehicle to vehicle control capable of reliable hard-realtime periodic control for longitudinal control. The infrastructure to vehicle control would also handle the hand off of the link from one road-side control unit to the next as the vehicle moves through the guideway. Any network management or other communications is done out of band ensuring the reliability of the control channel. The wireless protocol used for control communications would have deterministic worst case latency. Overall the guidance and control system would be safety instrumented to provide the necessary functional safety for such a high-speed transportation application.

The key costs for such a system come from the on-vehicle radars and the guidance system. The road-side radar reflectors should be comparing to the currently used paint based lane separation considering the reduction in maintenance cost and the huge leap the benefits. The radar systems on the vehicle should add costs to the vehicle in the range of $3000 which is not all that much in view of the benefits. A general improvement of average highway speeds to the tune of 20-30 mph is also foreseen. .Added to that would be indirect benefits to the economy as well.