City Controller Alan Butkovitz said yesterday an inspection by his office of 23 randomly selected city bridges found four with some significant deterioration, but none in danger of collapse.

Butkovitz said he undertook the review to see if the city Streets Department was properly maintaining and monitoring bridges in the wake of the 2007 Minneapolis bridge collapse that killed 13 people.

"In general, our inspections revealed that the bridges were in fairly good condition and that the [Streets Department] inspection reports accurately depicted conditions of the bridges," Butkovitz said.

But inspectors found rusting and corrosion on four bridges, which in two cases posed "serious safety hazards" to motorists, pedestrians or rail traffic that run underneath and could be hit by falling concrete or mortar.

The hazardous conditions involved the Henry Avenue Bridge over Wissahickon Creek and the Calumet Street Bridge, which crosses SEPTA tracks in East Falls.

In a written response, the Streets Department said that major work on the Henry Avenue Bridge was a PennDOT responsibility and that a contractor was working on repairs.

The department said the Calumet Bridge is in solid structural shape, and that a crew will be sent there to deal with falling mortar from a wall adjacent to the bridge.

The Streets Department agreed that its bridge- maintenance database should be computerized, and is working to achieve that.

Butkovitz also said his inspectors were troubled to find that large buses and trucks are routinely crossing the Willow Grove Avenue Bridge in Chestnut Hill, despite signs banning them because of deterioration in the bridge.

The Streets Department said a replacement bridge for that site was under design.