With closing speeds close to double the speed limit on a given road -- assuming nobody's speeding -- head-on collisions have the most horrific consequences among all traffic crashes.

But the often instantaneous nature of many such crashes mean many motorists have no chance to take evasive action when an oncoming car suddenly enters their lane, several traffic experts said Wednesday.

"There aren't tips for dealing with something like that -- things happen so fast," said Russ Rader, a spokesman for the Insurance Institute for Highway Safety in Arlington, Va. The best defenses, he said, are to always wear seat belts and drive vehicles that are designed to "perform well" in frontal-crash tests.

At 45 mph -- the speed limit on the stretch of Airport Highway where a car and minivan collided Wednesday afternoon, killing three people -- a vehicle travels 66 feet every second.

Double that for the rate vehicles approach each other, and they're a quarter-mile closer to each other every 10 seconds. Separate them by just a few hundred feet, and response time and maneuverability both have to be lightning fast to avoid disaster.

Mitch Wilson, a spokesman for the Ohio Insurance Institute, said remaining vigilant behind the wheel can help with evasive response.

But "if all of a sudden it's just right in front of you, there's not a lot you can do," he said.

Trooper Shane Johnson from the Ohio Highway Patrol's Bowling Green post, said he doesn't recommend swerving, or even attempting to put one's car in a deliberate spin-out to avoid a grille-to-grille impact. "If you lose control and end up in the path of someone else, it could cause a bigger problem," Trooper Johnson said.

The best reaction, if there is time to react at all, is to reduce speed as quickly as safety permits and steer away from the oncoming auto if there is room to do so, he said. Maintaining safe separation between one's vehicle and others and keeping an eye on that opposing traffic ensures that whatever reaction time there may be can be put to maximum advantage, he said.

Such emergencies are all the more reason for motorists to avoid distractions like cell phones, eating, reading, or applying make-up behind the wheel, Trooper Johnson said, but even the most attentive drivers may be unable to escape some head-on crashes.

"There are certain times that even though you're doing the best you can, some things are out of your control," he said.

First Published March 10, 2011, 6:39 a.m.