BANGOR (AP) – Construction crews were preparing to take a major and complex step to strengthen the Waldo-Hancock Bridge, whose support cables have weakened over the years.

Crews were getting ready to shift the weight of the span connecting Verona and Prospect from its old cables to 16 new ones. The state Transportation Department said this is the first time the process has been done in the United States.

It’s also the only example of cables being added to a bridge that was not designed for the addition, said DOT spokeswoman Carol Morris.

Project Manager Archie Wheaton of Cianbro Corp. said the complicated engineering process is time-consuming and involves a lot of unknowns.

“We’re just going to be careful not to go too fast and make sure we do it right,” Wheaton said.

The Department of Transportation closed the 72-year-old bridge over the Penobscot River to trucks after discovering the extent of its deterioration in July.

AP-ES-10-16-03 1342EDT