LORD, SAVE US FROM DRIVERS:

Most highways in major metropolitan areas operate under congested conditions during much of the day. Yet highways are designed around standards based on higher free-flow travel speeds that call for wider but fewer lanes. Driverless cars don't need the same wide lanes, which would allow highway authorities to reconfigure roads to allow travel speeds to be raised during peak travel periods. All that is needed would be illuminated lane dividers that can increase the number of lanes available. Driverless cars could take advantage of the extra lane capacity to reduce congestion and delays.

Another design flaw is that highways have been built in terms of width and thickness to accommodate both cars and trucks. The smaller volume of trucks should be handled with one or two wide lanes with a road surface about a foot thick, to withstand trucks' weight and axle pressure. But the much larger volume of cars--which apply much less axle pressure that damages pavement--need more and narrower lanes that are only a few inches thick.

Building highways that separate cars and trucks by directing them to lanes with the appropriate thickness would save taxpayers a bundle. It would also favor the technology of driverless cars because they would not have to distinguish between cars and trucks and to adjust speeds and positions accordingly.

Traffic management also suffers from obsolete technology that could hinder implementing the driverless car. On local streets, signal timing contributes to hundreds of millions of vehicle hours of annual delay because it is based on out-of-date historical data that inaccurately measure relative traffic volumes at intersections. Without signals based on real-time traffic flows, driverless vehicles may not be able to accurately align their speeds with them.

The future also holds the promise of new communications technologies that could let road authorities use electronic tolls to charge motorists for their contribution to congestion, based on actual traffic conditions, and thus encourage them to travel during off-peak periods, use alternate routes, or switch to public transit. Driverless cars would significantly help motorists respond to congestion tolls because their technology can balance the cost of a toll with its travel time savings to optimize motorists' route choices.

The driverless car represents one of the most amazing breakthroughs in safety and quality of life in recent history.

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