Location: Markham, Ontario
As a suburb city of the Greater Toronto Area, the City of Markham transformed the vehicle dominated Main Street of their downtown into something that better supported commercial and pedestrian activities. The strategy to accomplish this was the incorporation of healthy street trees to offer an inviting restoration to the streetscape and attract residents to the area’s restaurants and shops.
With existing traffic volumes warranting the widening of certain sections of the street to four lanes, the challenge was accomplishing this while still allowing for healthy street tree growth. The City’s plan widened the previously two-lane road to either four traffic lanes or two traffic lanes with curbside parallel parking, while implementing bump-outs at the intersections that reduced traffic to two lanes to both slow traffic flow while also providing a shorter crosswalk distance for pedestrians. These bump-outs are where the trees are located.
Engineered tree pits were used underneath the bump-out areas along both sides of the street. But in order to provide the required soil volume for the trees, the tree pit systems needed to flow from the sidewalk bump-outs out under the roadway. Connecting the soil cell system under the road to link the root space from the bump-outs on one side of the street to the other allowed for attainment of the soil volume necessary for the trees to reach maturity. However, this brought huge challenges due to the implications and structural requirements of the roadway. The only way to provide the uncompacted soil volume that the trees needed and still offer the load-bearing requirements dictated for the road construction, was with the use of GreenBlue Urban’s soil cell system.
RootSpace boasts the largest void space of any soil cell in the world while being H-20 vehicular rated with minimal surface. That’s why it’s been approved by engineers all around the world for use under vehicular trafficked areas. The high-strength capacity of the RootSpace system provides the structural strength needed to support maximum traffic loads, while giving the tree the soil volume necessary for healthy growth.
The use of GreenBlue Urban’s soil cell system under the road and across the street linked the tree pits on both sides of the street to maximize available soil and allow trees on both sides of the street to exploit higher soil volumes. “The structural integrity of GreenBlue Urban’s soil cells system to sustain heavy loads supported by solid technical evidence, coupled with a comprehensive range of components to suit each situation appealed to the City and drove us to choose GreenBlue Urban over the competitor,” explained Sally Campbell, an Urban Designer from the City of Markham that worked on the project back in 2012.
Dan Foong, the Project Manager, commented that they decided on the GreenBlue Urban ArborSystem because it offered a complete system, including soil cells, root management, irrigation/aeration, and tree grates – while with other soil cell systems, they would still need to source all the ancillary items elsewhere.
Cities like Markham that understand the benefits that healthy trees offer and have put a value on proper urban tree planting, know that trees to sustain their growth potential and provide the most benefit, they need as much root space as possible. Meaning that the anticipated reality that the available area for tree root space below sidewalks would be crowded with above and belowground utilities and infrastructure, doesn’t deter them from finding a solution. There is almost always a way to provide sufficient soil volume, in even the harshest urban settings, in order to achieve the desired results. “Having explored alternative methods of achieving the necessary soil volume, including an in-house tree pit design, as well as other options,” Campbell explained, “we saw the benefit and simplicity of the GreenBlue Urban system and opted for it’s use.”