Interesting Facts About Manhole Covers

Why Are Manhole Covers Round?

The most common question people ask. The answer is simple and ingenious: a circle is the only shape that cannot fall through its own opening. No matter how you rotate a circular cover, its diameter remains the same — it will never fall in. Additionally, round covers are easier to handle because you can simply roll them aside.

Japanese Artistic Manhole Covers

Japan is a paradise for manhole cover enthusiasts. Across the country, there are over 6,000 unique designs of manhole covers. Nearly every municipality, city, or district has its own cover featuring motifs that reflect local culture — flowers, animals, landmarks, or legends.

• Osaka features its castle and cherry blossoms
• Yokohama depicts the harbor and ships
• Nara showcases its iconic deer
• Since 2016, there are even collectible manhole cards, with over 900 different designs issued

Manhole Covers as Collectibles

Around the world, there is a growing community of enthusiasts who photograph and catalog manhole covers. This hobby is known as "drainspotting" — a wordplay referencing the popular film Trainspotting. Collectors travel across cities searching for rare, historic, or artistically interesting covers.

The Oldest Manhole Covers in the World

Some of the oldest surviving manhole covers date back to the Victorian era in London, from the 19th century. These cast-iron covers often feature ornate patterns and the names of the foundries that made them. Many are still in service today — a testament to the extraordinary durability of quality cast iron.

How Much Does a Manhole Cover Weigh?

A typical manhole cover weighs between 50 and 100 kg (110–220 lbs). Some heavy industrial covers can weigh up to 150 kg (330 lbs). The weight is intentionally high — it prevents displacement by vehicles and discourages theft.

Manhole Covers in Pop Culture

Manhole covers have become an iconic element of popular culture. The Teenage Mutant Ninja Turtles live in the sewers, and manhole covers are their gateway to the surface world. In many cities, tourist routes focused on interesting manhole covers have emerged — for example in Tokyo, Berlin, or Prague.

Cities with the Most Beautiful Manhole Covers

• Tokyo, Japan — hundreds of unique colorful designs across different districts
• Barcelona, Spain — covers with modernist patterns inspired by Gaudí
• Berlin, Germany — historic covers with the city coat of arms and manufacturer names
• Prague, Czechia — cast-iron covers with inscriptions from Czech foundries of the 19th and 20th centuries
• Seattle, USA — covers featuring a map of the downtown area

EN 124 Standard — Load Classes

The European standard EN 124 defines six load classes for covers and grates:

• A15 (15 kN) — sidewalks, pedestrian zones
• B125 (125 kN) — parking lots, sidewalks with occasional traffic
• C250 (250 kN) — curbs, hard shoulders
• D400 (400 kN) — roadways, streets — the most common class
• E600 (600 kN) — industrial zones, docks
• F900 (900 kN) — airports, docks with heavy machinery

Cast Iron vs. Composite — The Future of Materials

Traditionally, manhole covers are made from grey cast iron or ductile iron. In recent years, however, composite materials (GRP/FRP) have been gaining ground. Composite covers are lighter, corrosion-resistant, and have no scrap value — which significantly reduces the risk of theft.

• Cast iron: traditional, extremely durable, 100% recyclable, but heavy and prone to corrosion
• Composite: lightweight, corrosion-free, low scrap value, but lower load capacity at the highest classes