FRP Manhole Cover Load Classes Explained: A15, B125, D400 and More

Introduction

Choosing the right manhole cover isn’t just about size or material—it’s about performance under load. Whether it's a quiet sidewalk or a high-traffic road, each application demands a specific level of strength and safety. That’s where EN 124 load classifications come in.

In this article, we’ll break down the load classes commonly applied to FRP (Fiber Reinforced Polymer) manhole covers, explain their meaning, and guide you in selecting the right cover based on real-world needs.

What Is EN 124?

EN 124 is the European standard for gully tops and manhole tops, setting performance benchmarks for covers installed in vehicular and pedestrian areas. It classifies covers by their ability to withstand specific loads, ensuring both public safety and infrastructure reliability.

The standard defines load classes from A15 (light duty) to F900 (extreme duty), and mandates testing for:

• Static load resistance

• Deformation limits

• Material safety and durability

• Structural design

Common FRP Load Classes: A15, B125, D400

FRP manhole covers are typically engineered to meet three of the most widely used EN 124 load classes:

A15 – Light Duty (1.5 Ton)

• Use Cases: Greenbelts, sidewalks, residential gardens, pedestrian-only areas

• Recommended Cover Type: Light FRP cover with basic slip-resistant surface

• Advantages: Low weight, easy to lift, non-corrosive in outdoor environments

B125 – Medium Duty (12.5 Ton)

• Use Cases: Car parks, private driveways, slow-speed access roads

• Recommended Cover Type: Reinforced FRP cover with higher thickness and denser fiberglass matrix

• Advantages: Handles vehicle traffic up to small delivery vans or light-duty trucks

D400 – Heavy Duty (40 Ton)

• Use Cases: Urban roadways, industrial zones, main streets, freight terminals

• Recommended Cover Type: High-strength FRP cover with maximum fiber reinforcement, thicker cross-section

• Advantages: Comparable to cast iron in strength, but lighter, non-conductive, and corrosion-free

Comparison Chart: Load Classes at a Glance

Note: FRP manhole covers can be custom-engineered to meet additional classes such as C250 or E600 upon request.

Why FRP Manhole Covers Meet Load Requirements

FRP manhole covers are made using compression molding techniques with fiberglass reinforcements aligned in strategic patterns to bear load without deformation. The strength comes from:

• High fiber-to-resin ratio

• Directional reinforcement for traffic load zones

• Integrated frame-and-cover designs

• No corrosion fatigue, unlike metal covers that weaken over time

Many FRP covers not only meet EN 124 standards—but exceed them in durability testing, especially in environments with chemical exposure or moisture.

How to Select the Right Load Class

When choosing an FRP manhole cover, consider the following:

1. Where will it be installed?

• Sidewalks: A15

• Parking lots: B125

• Roads and intersections: D400

2. What kind of vehicles or traffic will pass over it?

• Pedestrians and bicycles: A15

• Cars and light trucks: B125

• Heavy trucks, buses: D400

3. What environmental conditions exist?

• High corrosion risk (coastal, chemical): FRP is preferred over cast iron

4. Any electrical or magnetic interference nearby?

• FRP’s non-conductive, non-magnetic properties offer added safety

GTOFRP™ Load Class Solutions

At GTOFRP™, we manufacture a full range of EN 124-compliant FRP manhole covers, covering:

• A15, B125, and D400

• Diameters from 500mm to 800mm

• Custom logos, locking mechanisms, anti-slip textures

All products undergo rigorous third-party testing to ensure compliance with both local and international standards.

Conclusion

EN 124 load classes serve as the foundation for safe and reliable manhole cover design—and FRP covers are uniquely positioned to meet these needs with a lighter, stronger, and more durable alternative.

Whether you're specifying covers for a park path or a heavy-duty roadway, understanding FRP load classes like A15, B125, and D400 ensures you're selecting a cover that’s not only strong but smart.

Let GTOFRP™ help you match the right cover to your infrastructure—ensuring safety, efficiency, and long-term performance.