Electric Avenue

New technologies could allow roads to carry more traffic with less pollution


Will we ever be able to deal with the problems of traffic congestion and automobile pollution? Mass transit is an often-proposed palliative, but cities that have built such systems—San Francisco, Atlanta, Washington, D.C.—have found that their subways bring no more than modest improvement at exorbitant cost. What's more, people like the cars they currently drive and show little interest in the 100-mpg wonders that occasionally appear in the news.

But even if cars and roadways do not change radically, new technologies can help us make better use of them. Several approaches would allow today's roads to carry much more traffic while producing much less pollution.

In Europe and Great Britain, several cities are installing networks of road-mounted sensors linked to a central station. The station interprets the data to determine which routes are less congested and transmits these conclusions to dashboard navigational systems that feature video displays of city maps, showing the drivers alternate routes. These same displays can give a driver directions to a destination or to the nearest gas station. They represent a classic instance of using electronics to present useful information to people. Moreover, the drivers who install such systems would immediately have distinct advantages over those who do not.

But other auto technologies offer little advantage to the purchaser, although they promise to reduce air pollution and congestion. An example is the electric-powered Impact automobile, of which General Motors has developed a working prototype. On paper, electric cars look great. They produce virtually no pollution when on the road. The pollution comes instead from the electric power plants, where emissions can be more easily controlled. And electric cars are small in size, easing problems of parking.

For most drivers, however, these points would be outweighed by a more immediate one: The electric car's cents-per-mile cost of operation would be twice that of a conventional auto. The reason is that such a car needs a battery pack, which is repeatedly charged and discharged. The pack wears out after about 20,000 miles and must be replaced—at a cost of $1,500. Long-lived batteries would obviously help, but they are still in the labs and far from ready for the roads.

The Impact's range is only 120 miles, and it requires a six-hour recharge. But this limitation merely makes it unsuitable for long trips; for daily drives to work or shopping, it could serve quite well. How, then, can we get buyers to overlook its high cost of operation?

The answer could lie in giving these cars preferential use on diamond lanes of freeways and on toll roads. Diamond lanes, often called high-occupancy-vehicle (HOV) lanes, are set aside for use by buses, car pools, and motorcycles. Traffic on them usually flows freely, even when the adjacent lanes are jammed at the peak of rush hour. Such lanes are particularly common in Southern California and the Washington, D.C., area, and other cities are likely to follow. Indeed, it is quite possible that new construction will be limited to diamond lanes adjacent to existing routes.

It would be a straightforward matter to encourage the use of electric cars by giving them special license plates and granting them free use of diamond lanes. Much the same would be possible with toll roads and with routes that include toll bridges or tunnels, which are widespread around New York City. A round trip into that city from New Jersey can easily cost $8.00. But electric cars might qualify for free or greatly reduced tolls, giving them further advantage.

This same strategy could work with what might be the ultimate solution to congestion: car trains. These amount to tailgating made legal. All the cars in a train would carry on-board radar linked to the brakes and accelerator, allowing them to follow quite closely while maintaining the fast reactions that would let them brake in time. The drivers would still steer, keeping their cars in the lanes, but the radar system would act as a very capable type of cruise control, maintaining speed and distance. Companies working on this concept include Radar Control Systems of San Diego and Vehicle Radar Safety Systems of Mt. Clemens, Michigan. Proponents of car trains declare that they would permit today's freeways to carry up to five times as many cars as at present, at full speed.

The problem is that these benefits would not be seen until large numbers of cars had such radars. Unlike car stereos or air conditioning, radar systems wouldn't offer immediate advantages to the first buyers, who would still rather be stuck in old-style traffic. Rather, like telephones or fax machines, the radars' advantages would depend on how many other people had also bought them. (Economists say such products have "network externalities.")

But if radar-equipped cars were also to carry special plates and to have preferential use of diamond lanes and toll routes, the picture would be quite different. As with electric autos, such advantages could provide the opening wedge that would launch a market for the radar equipment.

Such privileges, of course, would last only until the diamond lanes became crowded with the new-type cars. But by then they would exist in large numbers, and the auto and electronics industries would have gained extensive experience in their manufacture and use. Radar equipment might become standard on new cars, with more and more freeway lanes set aside for the car trains. Through such strategies, it might be possible to make the transition to a future world, where we continue to rely on our existing roads but use them with much greater effectiveness.

Contributing Editor T.A. Heppenheimer is a widely published science and technology writer.