America's Highway: Experts call it safest road system anywhere

Highway safety engineers found it hard to imagine.

A couple driving to Boston’s Logan Airport through a brand-new tunnel section of Interstate 90 in the still of the night had chunks of concrete and steel crash down on their car.

The driver escaped serious injury but his 46-year-old wife was crushed to death in the tunnel collapse on July 10, 2006, prompting a public furor and federal investigation into the safety of the notorious Big Dig project.

The I-90 tunnel was the last section of the nation’s longest interstate highway to connect Boston to Seattle over 3,020 miles of divided roadway. But it quickly became the poster project for shoddy safety.

Yet stories of death along America’s Interstate Highway System are relatively few. The Federal Highway Administration claims it is the safest road system in the world, and it has the death-rate statistics to prove it.

Highway death rates are calculated by the number of deaths per 100 million miles driven by all types of vehicles.

On the entire interstate system, the latest death rate is 0.8. That compares with 1.4 for other highways, and with 6.05 for the country’s highways before construction of an interstate network a half-century ago.

Pat Hasson, a safety and highway design engineer with the FHA’s office in Chicago, said that the Big Dig notwithstanding, the Interstate Highway System has lived up to its original purpose of making travel safer and more efficient in the United States.

He said the divided-road design has maximized safety and minimized problems at blind curves, steep hills, busy urban interchanges and high-speed on-and-off access roads. In some big cities, for instance, he said overpasses at major intersections can go as high as four levels to accommodate safe driving.

Hasson said engineers even give thought to the type of barriers they install on interstate highways. And, he added, it is not always a case of stronger is better, explaining that metal guardrails are more forgiving than concrete ones, and cable guardrails tend to cradle vehicles to controlled stops.

“We use the highest performance hardware to protect drivers and vehicles,” Hasson said. “Hitting anything is bad, but hitting a barrier is better than hitting what’s behind it” – especially when traveling at a high speed.

Because of their design, interstate highways carry the highest speed limits. Those limits are set by the states and can vary from 55 miles per hour to 80 miles per hour or more in wide open places like Montana.

But death-rate studies show that the number of fatal crashes went up dramatically on interstate highways when the federal government removed the energy-saving restriction of 65 mph in 1996.

Highway safety officials said the creeping death rate on interstates can be traced to higher speeds, reckless driving, drunken driving and more unsafe vehicles on the road.

They said the way to lower the rate is through stricter state enforcement of traffic laws, including wider use of radar-equipped aircraft and the use of unmarked police cars.