Every GridMats design names a grid: OC-HD 40, OC-LW 40 or the GP-30 grass paver. Clients often assume the heavier grid buys a thinner road. It does not. The grid carries the wheels at the surface; the layers below it are sized by the traffic and the soil. So the choice of grid changes the price, and the base stays the same.
To show this, we ran one car park and service area through the GridMats Design Engine with each grid and three kinds of traffic.
The three grids
| Grid | How to recognise it | Used for | Product, ex-works |
|---|---|---|---|
| OC-HD 40 | 40 mm deep, hexagonal cells with rows of rectangular cells along the panel edges; 6.6 kg/m² | Trucks and heavy plant: S1, S2, S4 and S5 | ₹84–107 per sq ft (₹900–1,150 per m²) |
| OC-LW 40 | 40 mm deep, open ring cells, staggered; about 4 kg/m² | Cars and lighter traffic in S1, S2 and S5 | ₹51–64 per sq ft (₹550–690 per m²) |
| GP-30 | 30 mm deep, small octagonal cells on a square grid; about 3 kg/m² | Grass for cars and fire lanes (S3); gravel for paths | ₹40–46 per sq ft (₹430–495 per m²) |
Product rates are by order size, ex-GST and ex-freight. A 40-ft high-cube container carries about 1,100 m² of OC-HD 40, 2,200 m² of OC-LW 40 or 1,500 m² of grass paver.
The site
- 3,000 m² (about 32,000 sq ft) of parking and service area
- Soil CBR 5%, flat ground, moderate rainfall
- Bengaluru rates, ex-GST, indicative
- GridMats S1, cement-treated gravel, and S2, stone chip
Same traffic, two grids
| Traffic | Layers below the grid | S1 on OC-HD 40 | S1 on OC-LW 40 |
|---|---|---|---|
| Cars and SUVs, 20 a day | 25 mm bedding, 150 mm GSB | ₹157 per sq ft (₹1,694 per m²) | ₹126 per sq ft (₹1,354 per m²) |
| Light commercial vehicles to 7.5 t, 30 a day | 25 mm bedding, 200 mm WMM | ₹173 per sq ft (₹1,864 per m²) | ₹142 per sq ft (₹1,524 per m²) |
| Two-axle trucks to 20 t, 40 a day | 25 mm bedding, 150 mm WMM, 125 mm GSB | ₹181 per sq ft (₹1,944 per m²) | The engineer's call, site by site |
S2 follows the same pattern: ₹156 per sq ft (₹1,675 per m²) on OC-HD 40 and ₹124 per sq ft (₹1,335 per m²) on OC-LW 40 for the car park, on 150 mm of open-graded GSB that stores the rain. Each section also has a non-woven geotextile separation layer on the subgrade.
What the numbers say
- The base does not change with the grid. For each kind of traffic, the layers below are the same on both grids. The traffic and the soil set them.
- The lighter grid saves about ₹32 per sq ft (₹340 per m²) on this site: about ₹10 lakh on 3,000 m². That is the whole difference, and it is all in the product.
- The traffic moves the base. From cars to two-axle trucks, the layers below the grid grow from 175 mm to 300 mm, and the cost by ₹24 per sq ft on OC-HD 40.
When we choose which
- OC-HD 40 for three-axle trucks, multi-axle trucks and tippers, container handling and S4 honeycomb-finish concrete. It is the Design Engine's default for every system except S3 and S6.
- OC-LW 40 for car parks, driveways, township roads and light commercial vehicles. At RINAC, Mumbai, the cold-storage yard is S1 on OC-LW 40 with 6% cement.
- GP-30 for grass: overflow parking, lawns and fire-lane access on a base we design.
- Between the two, for a few two-axle trucks a day, an engineer decides from the traffic count and the fill. The Design Engine names the lighter grid when it suits the load, with its saving, and the engineer switches only if the design allows.
How we design
The GridMats Design Engine uses layered-elastic analysis, with the IRC:37-2018 checks, including its rutting criterion, for the layers under the grid. An engineer reviews every design before it is issued.
Your site will differ
These are indicative figures for one typical site. Traffic, soil, rainfall, local rates, freight and order size change them, and every GridMats site is priced from its own design. Ask for your free estimate: our engineers follow with the design, the bill of quantities and the cost comparison against your conventional section.