Millions of people in the path of Friday's powerful storm knew what was coming and braced for the worst. Many hunkered down in their basements, warned by meteorologists who had tracked the storm over 600 miles as it gathered speed and strength and drew a bead on the Mid-Atlantic.

But just outside Annapolis, the Maryland Transportation Authority never considered temporarily closing the Bay Bridge, because an instrument atop the bridge was recording winds around 30 mph in the minutes before the storm.

"While forecasts are important and monitored continuously, a decision to close the Bay Bridge or any of our facilities is made on actual weather conditions," said Kelly Melhem, a spokeswoman for the authority.

When the storm struck, winds pushed a tractor-trailer against the concrete guardrail, tilting it precariously toward the water, its bleeding driver clinging to the steering wheel, struggling to get out. Behind him, motorists panicked.

"I called 911 and asked, 'Are we going to die on the bridge tonight?'" said Alessandro Vitale, a Baltimore restaurateur on his way to Ocean City. "I opened my sunroof so that if I went over the side, I'd have a way to get out."

"I thought the bridge was collapsing," recalled Allan Charles, a prominent Baltimore advertising executive whose car was behind Vitale's truck. "I thought the world was coming to an end. I called 911 and then called people to tell them goodbye."

Added Vitale, "They should have warned us."

The transportation authority has guidelines for closing its four bridges, and it stuck to them despite warnings issued by the National Weather Service and television meteorologists as the storm bore down on the Bay Bridge that night. Officials consider holding traffic when sustained winds are 50 mph or higher.

"We cannot simply close a major interstate and travel artery on the basis of a forecast projection alone, otherwise the Bay Bridge and other bridges would be closed quite often," Melhem said. "We are always prepared to act immediately in the event of an unusual weather occurrence like the derecho on Friday that took Maryland and neighboring states by surprise."

Maryland's closure policy mirrors that used by New York's Triborough Bridge and Tunnel Authority, which operates seven bridges, including the Verrazano Narrows span.

"We have anemometers on the bridges. When they read 60 mph, we shut the bridges down or we turn the vehicles around," said spokeswoman Marjorie Anders.

Lon Anderson, a spokesman for AAA Mid-Atlantic, called Maryland's policy "crazy."

"To suggest that we can't close a bridge when there's a forecast of imminent, vicious weather because an anemometer on the bridge doesn't say so is ridiculous," Anderson said. "There was no mystery here. We were warned, and the storm delivered."

He urged the state to take a second look at its policy in the wake of the near-tragedy.

Charles agreed.

"An anemometer? I cannot believe that's all they have. I have one of those at my house," he said. "They need to invest in something better."

But even with the technology at hand, the severity of the situation was evident.

On Friday at 10:10 p.m., the National Weather Service issued a severe thunderstorm warning for the Washington metropolitan area and surrounding counties for destructive winds in excess of 80 mph: "This is a dangerous line of storms. ... These storms are capable of producing destructive winds in excess of 80 miles per hour. This is a serious situation. You need to take cover now." A similar warning followed at 10:17 p.m. for the Baltimore region.

At 11:15 p.m., as the storm approached, the anemometer on the Bay Bridge that feeds data to the transportation authority's operations center showed sustained winds "in the low 30-mph range," Melhem said.

At 11:16, transportation authority police issued wind warnings, which flashed on the bridge, but didn't close it. Six minutes later, a blast registering 80 mph raked the bridge, "turning the night into hell," Charles said.