Of the games drivers play, it's one of the most hair-raising.
A lead-footed motorist will "stretch the green," as traffic engineers like to say, and speed through an intersection in defiance of an aging yellow or even a freshly lighted red traffic signal.
Sometimes, the driver behind will accelerate and follow, cruising blithely through the red. Occasionally, the next driver will scoot through, too, and maybe a couple after that -- all of them gambling that side traffic will hold back until the intersection is clear.
Most of the time, nobody gets hurt. But experts agree that it's a very nasty habit.
About a decade ago, public and private traffic safety experts in major cities -- including Baltimore -- began to complain about what they saw as a perilous trend: A significant fraction of drivers seemed to be slipstreaming through red lights in defiance of the law and, it seems, common sense.
"Some of it is right-turn-on-red violations, where they don't stop before making the turn," said William F. Zorzi Sr., public relations vice president for the American Automobile Association of Maryland. "Some people drive like you can make a right turn on red without stopping at all, without looking."
The number of tickets Baltimore police write each year for red-light violators has remained between 6,000 and 8,000 over the past eight years. Statewide, 28 people died in accidents caused by red-light runners in 1990, according to Maryland State Police statistics.
Some safety experts say drivers apparently began "stretching the green" because the nation's rising crime rate meant that police had less time to enforce traffic laws; because the pace of life has accelerated, breeding impatience; and because Americans became more skeptical about traffic signs and lights that seemed overly restrictive.
"It's part of the hurry-up, aggressive nature of our society today," said Cody L. Godman, president of the Safety Council of Maryland. "Everybody wants to be first. Nobody wants to wait."
Some think compliance with traffic signals in the Baltimore area will not improve without a massive police crackdown.
"Police monitoring of intersections is probably the only way to reduce the number of people who violate traffic signs and signals," Mr. Godman said.
But, he added: "It's almost an impossibility for the police to do that with great effectiveness. They can't sit at intersections all day."
There is some disagreement over how serious a safety threat red-light runners pose.
"It's a dangerous damn practice, you know?" said Mr. Zorzi, a sometime crusader on the topic. "The other guy assumes he's got the full green, and the other guy comes out of nowhere."
But in the March 1990 edition of the magazine Public Roads, Martin T. Pietrucha, a traffic engineer now at Pennsylvania State University, and three other researchers reported that most drivers who disobey traffic signals and signs appear to do so in a way that creates few hazards.
As part of a study for the Federal Highway Administration, the authors tracked 79,055 cars passing through 156 intersections in New York, California, Virginia and Texas. They found that about 1 percent ran red lights. Of those violators, only 11 percent drove in such a way as to cause other motorists to slow, turn or stop, creating at least the potential for an accident.
Although about a quarter-million vehicles were observed, Dr. Pietrucha said in a recent interview, no accidents were witnessed.
Red-light violators, the authors reported, seem to act only after calculating the risks. And, the authors reported, most seem to "assess risk correctly and act prudently."
But, Dr. Pietrucha said this week, his study did not show "stretching the green" is always safe, particularly at poorly designed intersections.
PTC Sometimes people make errors in judgment, and these can be hazardous. "It's not the kind of behavior we want to encourage, OK?" he said.
But neither is there much data suggesting a vigorous new enforcement effort is needed, some traffic safety experts said.
"I have no real data that shows it is worse than it's ever been before" or even that it constitutes a serious problem, said Sam Yaksich Jr., executive director of the American Automobile Association Foundation for Traffic Safety in Washington.
To launch a major red-light enforcement effort, he said, would require shifting scarce money and manpower from enforcing seat-belt, drunken-driving and other traffic safety laws.
Even if running red lights is not a major cause of accidents, Mr. Zorzi responded, the practice should not be tolerated. "That's a poor way to drive defensively, to think that, 'Everything's clear, so I'm going through the red light,' " he said. "That's just not right."
Tony Petralia, a veteran accident investigator with the Baltimore police, knows just how unsafe running a red light can be.