Trench Cover Load Classes: B125 to F900
EN 124 defines six load classes for trench covers and drainage gratings, from pedestrian-only (A15) to heavy industrial and airport use (F900). This guide explains each class, how to match it to your site conditions, and what frame and cover specifications follow from the class selection.
EN 124 load classes at a glance
| Class | Test load | Typical application | Cover specification |
|---|---|---|---|
| A15 | 15 kN | Pedestrian areas, cycle paths, green zones | Light grating or solid cover. No vehicle traffic. |
| B125 | 125 kN | Footways, pedestrian areas, car parks (car only) | Standard welded grating G325/30/100. Angle frame L63×63×6. |
| C250 | 250 kN | Road gutters, light vehicle areas, parking lots | G325/30/100 with mid-span support. Frame L75×75×8. |
| D400 | 400 kN | Roadways, factory driveways, loading docks, fire-access routes | G405/40/100 or heavy-duty grating. Reinforced frame with cross-members. Locking devices required. |
| E600 | 600 kN | Industrial yards, heavy truck routes, container storage | G505–G605 heavy-duty grating. Channel-steel frame [140–[180. Cross-braced. 10.9-grade anchors. |
| F900 | 900 kN | Ports, airports, crane operating zones, mining vehicle routes | G605–G755 grating. Double-layer reinforced frame. Full-penetration welds. Impact-rated. |
How to select the right class
Two questions determine the correct class:
- What is the heaviest vehicle that will cross the cover? A delivery truck points to D400. A fully loaded fire engine may require E600. A container handler points to F900.
- What speed will the vehicle be traveling? Slow-speed yard traffic is less demanding than highway-speed roadways. However, static loading from parked or turning vehicles can exceed dynamic loads.
When in doubt, select the higher class. The cost difference between C250 and D400 in grating material is modest compared to the cost of a cover failure under traffic.
What the class determines beyond the cover
The load class drives more than just the grating specification:
- Frame section: higher classes need deeper angle or channel frames with closer cross-member spacing
- Anchoring: D400 and above require bolt-down frames. B125 and C250 may use recessed gravity frames
- Locking: D400 and above require locking devices — standard hex-bolts or anti-theft bolts
- Panel splitting: covers may be split into shorter, lighter panels for manual handling. Vehicle-rated covers still need crane-assisted lifting for larger panels
Regional equivalents
EN 124 is the most widely referenced standard internationally. Equivalent standards include AASHTO H-20/HS-25 (USA), AS 3996 (Australia) and JT/T 327 (China). The load definitions differ between systems — always specify EN 124 class on the RFQ to avoid ambiguity.