The Contractor shall carry on the work in a manner which will cause a minimum of interruption to traffic, and may not close a street to through travel without the express approval of the Director of Operations. Where traffic must cross open trenches, the Contractor shall provide suitable bridges at street intersections and driveways. The Contractor shall post, where directed by the Engineer, suitable signs indicating that a street is closed and necessary detour signs for the proper maintenance of traffic. Prior to closing any driving lanes of a street, the Contractor shall notify responsible municipal authorities; including the Director of Operations, Police, Fire and School.