SAM SCHWARTZ, a.k.a. "Gridlock Sam," believes in New York City's "Don't Block the Box" policy.

He should, because it's his idea.

Schwartz, a traffic engineer and the New York Daily News columnist "Gridlock Sam," visited London in the 1970s and liked the city's approach to congestion problems: Slap drivers with tickets when they block intersections, and next time, they will get out of the way.

When he returned to New York, Schwartz launched a campaign to start the city's own "Don't Block the Box" policy. In 1982, his idea became reality.

Schwartz coined the phrase "gridlock" when he and his colleagues observed that one blocked intersection could choke up a whole series of Manhattan streets. "New York's streets follow a grid pattern, and a grid system is very sensitive to a single congested intersection," he said. With the anti-box-blocking policy, drivers' collective fear of punishment usually helps to keep intersections clear.

But it wasn't always just about punishment. "When the policy first was introduced, we gave positive tickets to people for not blocking the box," says Schwartz. "They were 'good guy' tickets which were redeemable for Radio City Music Hall passes or free subway rides. They disappeared several mayors ago."

Now, drivers only get the bad kind of tickets. But Schwartz still fully supports his policy, because penalities are necessary to change driver behavior. Schwartz feels some sympathy for the box-blockers; he knows that hard-driving New York culture can compel people to break the rules. "The problem is that a lot of drivers feel pressure from behind them. In New York City, you need courage not to block the box."

Contrary to the stereotype, Schwartz says that taxi drivers are New York's best drivers, and he thinks they are targeted unfairly by traffic cops. Full disclosure: Schwartz drove a cab before he became a gridlock guru.

He feels a strong personal motivation to fight congestion. "I hate traffic," Schwartz says on his Web site. "This may sound strange from someone who has made his living out of it, but I detest delays."