AUBURN – The South Main Street bridge that spans the Maine Turnpike will be closed indefinitely after it was struck by a tractor trailer hauling an excavator Thursday.

On Friday, turnpike engineers examined the bridge on Friday and discovered damage to the steel bridge beam, which was dented in the wreck an which has since formed a crack.

The question on Friday was whether the bridge will be temporarily fixed or if a complete rehabilitation will get underway.

Police said a flatbed truck carrying an excavator struck the side of the bridge on Thursday. Nobody was hurt in the crash but turnpike officials deemed the bridge too unsafe to keep it open. They estimated it will be several weeks at least before the bridge is open again.

The wreck and subsequent damage is reminiscent of a similar crash in August 2005 in which an excavator flipped off the back of a truck and damaged the nearby Hackett Road Bridge. That bridge remained closed for two months while repairs were made.

According to Dan Paradee, of Maine Turnpike Authority, the bridge was scheduled to be completely rehabilitated in 2008. On Friday, turnpike officials were gathering information to decide it is more feasible to make temporary repairs or to begin the rehabilitation a year ahead of schedule.

Police meanwhile, were advising drivers who use the bridge to plan out other routes. South Main Street traffic is being rerouted onto Witham Road, to Broad Street, to Hackett Road and to Old Danville Road and back to south Main Street.

Police said the area will be clearly marked with detour signs.