A driveway to five new dwellings was granted access at planning stage through a Root Protection Area (RPA) on the understanding that tree roots would not be damaged.
Green grid's involvement didn’t start until the houses were completed, when the developers found that their original plan to use a concrete slab set on concrete piles wouldn’t work.
There was a gradient across two planes where the driveway slopes up from the road. Green Grid was able to modify its heavy duty tree root bridge system to accommodate this – something that wasn't achievable with the concrete option they had originally chosen.
The solution consisted of the RB heavy duty tree root bridge system, which is rated to take vehicles up to 30 ton, with stub legs set at specific angles and heights to connect to the piles and manage the gradients.
The system in this project was left as a mesh finish at the client’s request, with a heel friendly mesh size and anti-slip serrations. The remaining RPA area between the system and the rest of the driveway was finished with 200mm deep geocells.
Temporary ground protection was used onsite when tracking the machine through to install the screws. These were 2100mm long to meet the high load requirement of the system and wound into the underlying chalk.
The final system allows access for vehicles up to 30 ton whilst not compromising the soil conditions around the trees while the open grid allows the natural transfer of moisture and air to continue unimpeded.