Perpetual Pavement Trial

For the past several years Ministry of Transportation (MTO) engineers have been busy designing, constructing and implementing Ontario's first ever Perpetual Pavement Trial. Perpetual Pavement is a thick asphalt pavement consisting of a flexible, fatigue-resistant, asphalt-rich bottom layer, a strong rut-resistant middle layer, and a smooth, durable renewable surface layer. The bottom layer is comprised of a Superpave25 (SP25) mm Rich Bottom Mix, which is waterproof and more flexible than conventional asphalt mixes.

The objective of using perpetual pavement on highways is to provide a significantly longer road-life than a traditional asphalt pavement. The benefits of using perpetual pavement include ease of maintenance, quick and easy repair, and a smooth and quiet drive for Ontarians.

Highway 406 in the Niagara Region, near Thorold, was selected as the location for the first Perpetual Pavement Trial. The project consisted of twinning an existing 2-lane section of Highway 406 into a 4-lane divided freeway for 5.2 km.

The project was split approximately in half from a pavement design perspective. The north portion has a conventional deep strength asphalt design while the southern half was constructed as the perpetual pavement trial. Grading and earthwork began in late fall 2005. The ministry's first SP25 mm Rich Bottom Mix was laid down in November 2006 and the remainder of the Perpetual Pavement was placed throughout June-July 2007.

The Perpetual Pavement Trial was officially opened to traffic in August 2007. The mix design, placing and compacting was successful, and field reviews have since been carried out. The ministry will be monitoring the performance of this trial section compared to the adjacent conventional flexible pavement design, which acts as a control section. Monitoring will include annual distress surveys to evaluate cracking and use of the ministry's Automated Road Analyzer (ARAN) to measure pavement roughness and rutting.