What does c250 manhole cover mean?

It means that the center point is stressed for 250 kn for five minutes, and the manhole cover can still be used normally.

In Japan, most manhole covers have unique numbers and will be included in the sewer management system. Taking Tokyo as an example, the Tokyo Sewerage Bureau gives each manhole cover a unique number, which consists of the manhole cover type, the manhole cover identification code and the manhole cover construction date. On the one hand, it can quickly identify the damaged manhole cover, on the other hand, it can know when the manhole cover expires and should be repaired and replaced. Most manhole covers in Japan are maintained by private public utilities.

In addition, the pattern design and shape of Japanese manhole covers vary from region to region and from department to department. The sewers managed by the municipal, district and town governments are distinguished by the city flowers, district flowers and town flowers on the manhole cover. If the manhole cover is damaged and needs maintenance, the responsible subject can be determined immediately. For sewers owned by individuals, the word "private" and the owner's surname will be marked on the manhole cover to show the difference. The manhole covers of fire hydrants are mostly rectangular or engraved with cartoon patterns of firefighters.

Japan is a country with frequent natural disasters, and there are "emergency shelters" near residential areas. Some manhole covers around the shelter are painted in color in addition to indicating the direction with arrows. The yellow arrow means within 200 meters from the shelter, while the red arrow means within 100 meters from the shelter.