There is a ravine behind our house (much of which is our property) with a busy road behind it. The ravine is home to many big leaf maples, alders, and shrubs, with a creek at the bottom. When the trees lose their leaves, the noise from the road carries into our backyard, and you can see cars driving by. The yard and ravine are east/south east facing.
This is in Delta, BC, Canada. Which evergreen(s) will grow quickly to a large size, and provide a thick canopy to block the view and noise from the road? Ideally it would also have an extensive root system to help prevent erosion on the slope. Note that this will not be a hedge, as they will need to be quite tall to fully obstruct the view from the road, and the topography does not allow for planting in a straight line.
The property is already home to a western redcedar and a beautiful old Atlas cedar, both of which appear healthy and mature.