The city overlays 3 to 5 miles of city and county arterial streets (main roads) in Saint Paul each year depending on funding availability. The projects are distributed about the city on a priority basis incorporating the city’s Pavement Management System. The city produces the asphalt at its plant and places the asphalt overlay surface. The city contracts out the milling operation to a local contractor.
Parking is restricted in the immediate area of the work. Parking restriction signs are posted 24 hours prior to work starting for both the milling and the overlay operations.
The mill and overlay process is done under traffic. Milling takes one to two days in a given street segment. They overlay is placed in one day or possibly two days depending on width of roadway and traffic conditions.
The original asphalt pavement is milled off a depth of 1 ½” the full width gutter to gutter of the street. The machine used is called a milling machine.
Traffic may travel on the milled surface. Temporary traffic controls will be put in place after the milling is completed. Within a few days the paving crew will show up to place a new asphalt overlay pavement.
Before the pavement is placed, the surface of the milled pavement is covered with a liquid asphalt tack coat to bond the old and new pavements. The tack coat is applied by hand or by distributor tanker truck.
The new asphalt overlay is placed at a depth of 1 ½” using a machine called a paver. Hot asphalt (350 degrees F)is brought in by dump rucks from the City’s Asphalt Plant. Each truck carries about 10 tons per load. The overlay crews can quickly lay down 400 to 600 tons of asphalt per day.