New state Transportation Department Secretary Lynn Peterson has ordered a review of three megaprojects: a new Interstate 5 bridge crossing the Columbia River, and the new Highway 520 floating bridge and the tunnel replacing the Alaskan Way Viaduct in Seattle.

Each project costs billions of dollars.

Peterson said Thursday the assessment would be led by a program manager for the CH2M Hill engineering company, Ron Paananen. He's the former DOT project director for the Seattle tunnel project.

His review is due by the end of September. He'll recommend ways to clarify lines of decision-making, resolve disputes and hold down costs.