A midafternoon fire in a construction zone of Baltimore-Washington International Airport brought traffic on nearby roads to a standstill and inconvenienced some passengers.

The fire broke out about 1:25 p.m. in the Pier A construction area, said Paul J. Wiedefeld, executive director of the Maryland Aviation Administration, which oversees the airport.

Workers who were removing debris from the roof noticed a spark, and construction workers were quickly evacuated. Although smoke was visible from miles away, the fire was out by 2 p.m.

Airport officials closed the upper-level drive to accommodate emergency response equipment.

Fire departments from Anne Arundel, Baltimore and Howard counties assisted BWI's fire rescue personnel in extinguishing the blaze.

"We're in a very slow period of the day, so, no, there was no impact on flights at all," Wiedefeld said yesterday afternoon.

Construction crews were working on demolition at Pier A as part of BWI's $1.8 billion expansion plan, Wiedefeld said, so damage was minimal.

Demolition is scheduled to be completed in April, said Harriett Sagel, a BWI spokeswoman.

The pier was used by United Airlines before their operations moved to Pier D.

Pier A is being readied for Southwest Airlines, which will move from its current location.

The rebuilt Pier A, which is scheduled to open in 2005, will allow Southwest to combine its operations at the airport and provide extra gates for the airline.

Officials closed the Pier B security area - the closest one to the site - for about 20 minutes as a precaution, which resulted in crowding in the terminal. The cause of the blaze is under investigation.