Many believe that the highway congestion experienced in virtually all major urban areas in the United States is the most serious impediment to continued economic growth. Space limitations and cost will probably preclude the construction of significant quantities of new highway in the immediate future. As estimated from several recent freeway projects in Los Angeles, highway construction cost in Los Angeles County is approaching $12 million/lane per mile. To make a modest increase of 25% in the number of highway lane-miles in the Los Angeles County urban area would represent an investment of the order of $12 billion. (The costs are presumed to be similar for other urban areas in the United States.) It is not realistic to suppose that funding support of this magnitude would be available, or necessarily advisable. Rather, it is the more efficient use of the presently available highway system that is the focus of the automated highway (AHS) concept. To improve the operation of the highway system, two solutions might be considered: either decrease the average vehicle width to produce more lanes of traffic, or increase the traffic flow of existing lanes. Automobiles and trucks can be made narrower but not significantly so, and only at great cost. The second choice is more compelling because large improvements in the flow (or throughput) along a highway are possible by incorporating the orderly movement of vehicles, together with a reduction in the longitudinal spacing between vehicles. Both items are contained in the close-following concept.
KeywordsWind Tunnel Drag Coefficient Drag Reduction Lead Vehicle Wind Tunnel Measurement
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