A Maryland Transportation Authority Police sobriety checkpoint set up late Saturday near the Key Bridge toll plaza stopped 597 drivers, six of whom were arrested.
The effort - staged at the only point on the Baltimore Beltway where most vehicles ordinarily have to stop - was part of what transportation authority police said will be a continuing enforcement tactic against drunken driving at toll facilities it patrols.
Six drivers, one of them a juvenile, were arrested during the four-hour operation, which ended at 3 a.m., according to Cpl. Gregory Prioleau, a police spokesman.
Holiday weekend checkpoints were established across the country in connection with National Sobriety Checkpoint Week, which ends tomorrow. The initiative is sponsored by Nationwide Mutual Insurance Co. in conjunction with Mothers Against Drunk Driving.
Prioleau said that checkpoints "are effective ways to keep drunk drivers off the roadways."
The Labor Day weekend is one of the heaviest travel times of the year, according to AAA Mid-Atlantic.
Nearly 500,000 residents of the Baltimore-Washington area were expected to be traveling out of state, 83 percent of them by car, said Mahlon G. Anderson, a spokesman for AAA. He said traffic will be "extremely heavy" today as weekend travelers and summer vacationers head home.
During the Key Bridge operation, signs alerted motorists two exits in advance of the checkpoint. Toll-takers handed out informational literature on the dangers of driving under the influence, and field tests - including Breathalyzers - were administered to drivers who appeared to be under the influence.
It was the second sobriety checkpoint this year at the Key Bridge. During the first checkpoint in April, police stopped 560 cars and reported 13 arrests.