Pipe plus a slotted drain provides favorable economics plus speed for nighttime installation on expansion project
A two kilometer stretch of Highway 401 in Toronto is being reworked and expanded to accommodate current and future traffic volume. It’s part of a $640 million, 6.21 mile project by the Ontario Ministry of Transportation, to reduce congestion, shorten commute times and encourage economic growth in the region. This section of Highway 401 is one of the busiest of any highway in North America with an annual average daily traffic of more than 420,000 vehicles. Some travelers report it’s typical to take 30 minutes to move 500 meters (a third of a mile). Included in the scope of work scheduled to be completed in 2022, are 10- and 12-lane roads, high occupancy vehicle lanes, new and reconstructed bridges, utilities and upgraded storm water drainage systems.
To handle storm water runoff, the new construction involved the installation of Advanced Drainage Systems, Inc. Duraslot slotted surface trench drains in 300 mm and 375 mm (12 and 15 inch) diameters, which was a first for a major 400-Series highway. Brennan Paving & Construction, Ltd., a division of The Miller Group, installed the drains at night during a two-month period so that the work could be done without impacting the flow of traffic, which is a prime transportation link for the Ontario economy. A total of more than 2,200 meters (7,218 feet) of pipe was installed in the separator between the express and collectors, which run east and west.
The pipe is made from dual-wall corrugated high-density polyethylene (HDPE) pipe with an aluminum slot mounted on top and is designed to intercept sheet flows of water across paved or cleared areas. It is a substitute for corrugated steel slotted drains, precast trench drains, cast-in-place trench drains, catch basins and curb inlets. An outer corrugated wall provides strength and durability, while the smooth interior lining gives exceptional hydraulics. It was typical for the Brennan crew to install 60 meters (197 feet) a day.
Duraslot has the same inlet as corrugated steel pipe slotted drains. A 45 mm (1 ¾ inch) wide opening runs the length of the pipe and special connectors provide for a continuous slot of virtually unlimited length. For curb and gutter applications, the inlet acts as an orifice and the AISI Handbook method can be used to determine hydraulic capacity.
The total Toronto Highway 401 project is being delivered through a design, build and finance, public-private partnership model, which transfers risks associated with design, construction and financing to the private sector. Using the design-build approach has allowed the designer and contractor to work together collaboratively with the project’s stakeholders.