Location: Cambridge, Ontario
Local residents and store owners in Cambridge, Ontario have found much to like with the Main Street renovations that took place in 2011. “The recent downtown renovations aim to boost street traffic and improve pedestrian sidewalks.” The project’s completion was celebrated recently in Cambridge to kick off Galt Grand River Festival celebrations.
“It’s phenomenal,” said a local resident who sat outside what will soon be his storefront. “Personally, I’ve got a thing for the benches,” he said, gesturing at a black bench that looks more like woven ebony ribbon than crisscrossed metal. He also likes the trees, which are, surprisingly, one of the more contemporary aspects of the streetscape. Arand hopes to watch the trees grow alongside his business.
The irrigation system that runs beneath the octagonal grating surrounding the tree trunks is designed to increase their longevity. “They provide a better growing environment for the trees,” said the GreenBlue consultant who worked on the project. StrataCell modules are patented, load-bearing plastic modules with vertical and lateral interlocks which create void space beneath sidewalks.
After a suitably sized tree pit has been dug, taking into account the mature rooting area of the selected trees, multiple layers of StrataCell modules are placed in the pit and snapped together to form a matrix. An opening for the tree root ball is provided within the matrix. These unique load bearing modules provide structural support for the sidewalk and adjacent roadway while creating a soil-filled void for healthy tree root growth. The cells prevent the soil becoming compacted, ensuring the roots can establish and obtain oxygen, water, and other nutrients vital to longevity.
The notoriously high bedrock of Cambridge caused a challenge for the trees however. While the original plan specified that the tree pits be placed under the sidewalk and adjacent to the building fronts, it was not possible to blast through the bedrock without the risk of damaging the buildings. This created a huge problem for the landscape architect and the project at whole, until GreenBlue Urban stepped in with the solution of bringing the tree pits under the roadway to maintain the originally planned size of the tree pits. This was only possible because of the high load-bearing strength of the StrataCell, which is able to withstand high traffic loads.
The city wanted to create a more pedestrian-friendly and accessible street in attempt to draw and keep more entrepreneurs into the area, so the idea of keeping the trees closer to the roadway to increase pedestrian area was ideal. The spacious walking area also highlights the beautiful architecture of the old buildings in the core. “The overall look really does tie in with the buildings and it does seem more spacious” said the landscape architect representing the City of Cambridge, adding, “even though we didn’t change the width of the sidewalk.” The incorporation of these tall attractive looking Ornamental Pears and Princeton Sentry’s are a welcome improvement, and worthwhile investment to the Main Street. This project has been a great opportunity for the City of Cambridge to compare the latest structural cell technology (incorporating larger soil volumes), with the traditional rock soil-matrix method of planting trees in pavement. Above and below ground solutions are available through GreenBlue Urban to provide tree support and protection.
This project doubled as an in-situ tree pit trial site, as trees on this block were planted not only in soil cells but also in structural soil. Four identical Linden trees were planted on the same side of the street between Water Street and Ainslie Street – two planted in soil cells and two planted in structural soil. Each tree pit was 28 ft x 6.5 ft x 2 ft (8500mm x 2000mm x 500mm).
Due to the fact that structural soil is about 80% stone and 20% soil, that means the trees in structural soil received approximately 2.6 cubic meters (92 cubic feet) of soil volume. Since an assembly of soil cells provides over 95% usable soil, the trees in soil cells obtained approximately 8.5 cubic meters (300 cubic feet) of soil volume per tree – even though they were planted in the same size tree pit. At time of planting, you wouldn’t have known which of the systems each tree was planted in. Years later, the photos speak for themselves.