Highways as Speedways? Drivers Push the Limits
Traffic experts say growing number of American drivers are pushing highway speeds to new heights each year; more drivers are treating speed limits as suggestions, steering bigger and more powerful cars and exploiting increasingly lax police enforcement; trend has drawn little public notice, overshadowed by more visible problems like drunken driving and supposed 'road rage' epidemic; is veiled also by fact that highway deaths have been falling for years; even though Americans are driving more than ever, fatality rate per highway mile has declined 11 percent since 1995, when federal government abandoned national speed limit of 55 miles per hour; photos (M)
