TRAFFIC TERMINOLOGY

Perpetual pavement

A pavement design that includes multiple layers meant to make the road more resistant to cracks, fatigue and rutting and last 50 to 70 years. The Red Hill Valley Parkway was one of first to use it in Ontario in 2007.

Stone Mastic Asphalt

An asphalt mix that uses high-quality fine and coarse aggregates that are mixed together with a higher volume of liquid asphalt (like glue). It is more expensive and more resistant to cracks. Initially, it can have less friction but after a few months of wear that “polishes” the aggregate, it can have better friction than other roads. Originally created in Germany in the 1960s, it is used on the highest-volume roads in Ontario.

Superpave mix 12.5 FC2

A standard and less expensive asphalt mix used on high-volume (but not the highest volume) freeways in Ontario. Superpave mixes were developed in the United States in the 1990s. It uses a denser grade of aggregates and less asphalt in mix than SMA. It’s expected to be used when the city “shaves and paves” the top layer of the Red Hill starting next year.

Crossover crash

A collision where a car travels through the centre median and crashes in the opposite lanes. Six of the 11 deaths on the Lincoln Alexander Parkway and Red Hill Valley Parkway were in crossover crashes.

Barriers

There are not continuous median barriers dividing traffic travelling in opposite directions along the Lincoln Alexander Parkway and Red Hill Valley Parkway. There are some limited barriers around structures. Experts say barriers typically reduce the severity of crashes, but can actually increase the number of crashes.