All the balcony railings at the Alexandria Knolls condominium will be reinforced, an Alexandria city official announced last week. The action comes after a 16,000-pound, 40-foot railing outside a 12th-floor apartment plunged to the ground and sank eight feet into the earth on April 29.

Charles Everly, Alexandria's director of building and mechanical inspection, said that the Formigli Corp., the company that manufactured the pre-cast concrete used to build Alexandria Knolls, decided to take the "conservative approach" and reinforce all the railings after cracks were found in several during a recent inspection.

"Cracks in concrete, masonry and plaster are common things. You usually don't worry about them," said Everly. "But that's part of the problem in this case and that's why we've got a piece of concrete out there in the ground."

The 12th-floor railing fell early in the morning and no one was injured. It narrowly missed an electric generator and parked cars, and cut off telephone service to the building for most of the day. The incident also upset many residents, who worried that it would be unsafe to lean on their balcony railings.

Some of the condominium railings have already been reinforced with temporary wooden bracing, Everly Formigli, a New Jersey-based corporation, has agreed to reinforce all of the railings with a 7 1/2-inch steel channel, bolted to either side of the building's walls, he said.

The occupants of the condominium unit that had the faulty balcony railing complained to the building managers last December that their balcony was cracking and slipping, Everly said. Engineers representing the builders were sent out to inspect it, and determined that there was no serious problem, he said. Everly added that the engineers "made a serious error in judgment."

City building inspectors were not called, Everly said.

He said he is not certain whether the city's building code was violated by the builders of the condominium and added that he is more concerned with making certain that railings are safe. Formigli is cooperating fully with his department, Everly said.

Several attempts to reach Formigli officials for comment were successful.

Everly said it appears that the building, occupied for two years, was built with bearing pads that were too small to attach the railings to the walls of the Alexandria Knolls building.