Solar Farm and Utility Access Roads
Permeable access and maintenance routes that carry construction and service traffic without adding impermeable area to the site.
Why reinforcement matters here
Utility sites are typically consented on drainage and landscape conditions that a bound access road immediately complicates. A reinforced permeable route carries construction plant and ongoing maintenance traffic while keeping the site's runoff profile close to greenfield, which is usually what the consent requires.
Where this works well
At a glance
| Sub-base | Designed to the construction phase loading, typically 200-250mm MOT Type 1 |
|---|---|
| Infill | Angular 20-40mm crushed stone; grass infill where a landscape condition applies |
| Typical loading | Construction plant during build, service vehicles thereafter |
| Permeability | Fully permeable. Normally treated as a SuDS component in a drainage strategy. |
| Design life | 25 years, subject to documented installation. |
| Material | 100% recycled polypropylene, made in the UK. |
How it goes in
- Mark out the area and excavate to the depth of your sub-base plus the grid depth plus your infill blinding.
- Lay a woven geotextile across the formation, lapping joins by at least 300mm. This stops the sub-base and the subsoil mixing.
- Lay and compact the sub-base: Designed to the construction phase loading, typically 200-250mm MOT Type 1. Compact in layers rather than all at once.
- Blind the sub-base with a thin layer of grit sand and screed it level. This is what gives you a flat finished surface.
- Push-fit the grids together across the area, working from one edge. Cut around obstacles with a jigsaw or fine-tooth saw.
- Fill the cells: Angular 20-40mm crushed stone; grass infill where a landscape condition applies. Work the fill in with a stiff brush so no cell is left hollow.
- Check the finished level. Nothing should stand proud of the cell walls, and no cell should be left under-filled.
Most installations are straightforward groundwork. The grids themselves push-fit together and need no fixings, adhesive or specialist tools.
Which grid depth?
The 30mm heavy duty grid for access roads and hardstandings. Where a landscape condition requires grass, the 40mm general duty grid is used on the affected sections only.
If you are between two options, take the heavier duty one. The cost difference across a typical project is small next to the cost of lifting and relaying a surface that was under-specified.
The mistake we see most often
Designing for the maintenance vehicle. The crane, the piling rig and the delivery lorries all arrive first, and they govern the build-up.
Common questions
Will it take construction plant?
Design the sub-base for the construction phase, not the maintenance phase. Construction traffic is almost always the governing case.
Does it help with the drainage condition?
Yes. A permeable surface keeps runoff close to greenfield rates, which is often the point of the condition.
Can it be grassed for visual mitigation?
Yes. Grass infill is common where a landscape condition applies to the site boundary.
What about long term maintenance access?
The surface remains trafficable year round, which is the practical requirement for scheduled maintenance visits.
Does it help with the drainage condition on the consent?
Yes. A permeable surface keeps runoff close to greenfield rates, which is usually the basis of the condition.
What happens at decommissioning?
The surface can be lifted and the stone recovered, which supports a restoration condition better than a bound road.
Ask our engineer
Questions about depths, sub-base, edging or which system fits your project? Ask below.