Which cover class you need is the specification that fails most often — and it is decided by one question: what is the heaviest thing that will ever cross this chamber?
The short answer: BS EN 124:2015 splits access covers into six classes by tested wheel load. Match the class to the heaviest vehicle that can reach the chamber, not to the traffic on an average day. If a truck can reach it, specify D400.
This is the standard referenced by Dubai Municipality, Abu Dhabi Municipality and DEWA drawings, and it is the number that gets a cover rejected at inspection — not the chamber size, the depth or the invert levels.
| Class | Test load | Where it belongs |
|---|---|---|
| A15 | 15 kN | Pedestrian and cycle areas only. Green belt, landscape, terrace. No vehicles. |
| B125 | 125 kN | Footways, pedestrian zones, plazas and car parks used by cars only — no delivery lorries, no bin trucks. |
| C250 | 250 kN | Kerbside and gully positions, the strip at the edge of the road where a wheel may mount but running traffic does not sit. |
| D400 | 400 kN | Carriageways, site roads, hard shoulders and parking areas. The class called for across trafficked roads and most site access. |
| E600 | 600 kN | Docks, ports, container yards — loaded forklifts and heavy axles. |
| F900 | 900 kN | Airport pavements and aircraft loading. Unless your drawing says aircraft, you do not need it. |
Most specification errors happen between these three.
Yes. SMC composite covers are routinely moulded and proof-loaded to C250 and D400; E600 and F900 are available on request. The cover is marked with the class it was tested to, and a load test report ships with the order.
The honest limit: for wheel loads beyond E600, or where an existing municipal specification fixes ductile iron, cast iron or ductile iron remains the right call. Composite wins outright in coastal cities, on sites with recurring theft losses, in smart-city pilots, and wherever installation labour is expensive or scarce.
Give us the clear opening, the load class and the annual quantity. You get a price, a drawing and a delivery date — usually within two working days.
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