MINNEAPOLIS -- A radio-controlled sub plies the Mississippi. Navy divers probe for bodies. FBI teams map the river bottom. Crews marshal cranes that will lift concrete and mangled steel.

Work at the site of the Interstate 35W disaster became a delicate balancing act Monday between recovering bodies and removing tons of debris from land and water.

Officials stressed that the dual operations will be slow. The cleanup could cost $15 million and take months to complete.

“It’s not a situation where you’re going to see big hunks of debris taken away,” said Bob McFarlin, assistant to the Minnesota Department of Transportation commissioner. “It’ll be cars and small bits of debris.”

In the early stages, divers and others will direct cleanup crews to areas where vehicles may be crushed and bodies may be trapped. That work will be tedious, officials said, as heavy objects are carefully lifted and divers sent in to take a look.

"There are a lot of resources being committed here and we're going to get this job done," Hennepin County Sheriff Rich Stanek said, referring to the search for bodies.

The FBI’s unmanned submarine will bring sonar, lights and cameras to the search for bodies. An FBI evidence recovery team also will use special equipment to map the vehicles and pieces of the collapsed bridge.

The unprecedented task of hauling cars, concrete and steel from the Mississippi River will eventually include about four cranes, two huge barges and dozens of workers.

Cleanup crews also will try to protect debris as part of the investigation into last week's collapse.

"It's not a matter of just going in and taking things out and throwing them on the barge," Terry Zoller, a Minnesota Department of Transportation construction engineer said. "We will take pieces out very methodically and be placing them on the barge so that we can examine each piece. It's a very slow, tedious process."

The state hired St. Paul-based Carl Bolander and Sons to do the work. Eventually, the cleanup company plans to put cranes on each side of the river, one in the middle and a fourth at an unloading site.

Workers will focus on first hauling debris from land. Then they will move into the river channel.

Barges will haul debris away. Before that heavy work can begin, cars and other material may need to be removed to clear a path for the barges.

Federal investigators will keep an eye on the operation. National Transportation Safety Board officials will advise crews about what should happen to each piece of debris. Investigators plan to reassemble portion of the bridge to help determine why it failed.

The cleanup is expected to take months.

Until all the missing people are found, crews will work closely with firefighters, police and other authorities on the recovery mission. Officials believe some, if not all, of the missing are trapped in the debris. Searches in a six mile stretch downriver from the collapsed bridge have not found any bodies.

Divers continued searching for victims Monday.

Also, the region coped with its first Monday rush hour since the collapse wiped out a major route into downtown Minneapolis. Officials reported no big jams or other problems. Thousands of commuters, trucks and buses found alternate routes or didn't hit the road at all.

"Overall, it was lighter than expected, given the circumstances," said Todd Kramascz, a state traffic operations supervisor. "A lot of people avoided the entire corridor."

A Minnesota State Patrol supervisor said motorists appear to be taking the changed freeway landscape in stride. "Drivers are taking heed," said Major Al Smith. "We don't see the aggression with the drivers."