Below the surface of each major city is a system of public works such as sewers, rainwater sewers, tunnels, and many other utility systems. The entrance of these systems is called manholes – dug down underground pipes for maintenance personnel to work.
• Basic features of the manhole cover
Pits can be quite shallow or deep. The manhole cover is a circular plate sinking down the street and the sidewalk to avoid passersby from falling into the manholes.
Sewer covers must have a minimum diameter of 22 in. (56 cm), but may have a diameter of 60 in. (nắp hố ga tiếng anh là gì). The medium shell weighs between 250 and 300 lb (113-136 kg). It is important for the drain hose to be heavy because the drain can produce methane that can push the lid off the road, causing harmful gases to enter the street.
• How old are the manholes and manholes?
As soon as people started living in cities, issues related to human waste became a problem. The first cities were built along major rivers so that these rivers responded as drainage sewers.
However, because too many wastes are generated, the drainage source is so close that many diseases have arisen. Roman civil engineers solved this problem by inventing an underground drainage system. Roman drains were dug by hand and lined with brick, garbage collected by the city and flowing downstream. The Romans built access to these sewers to allow for periodic cleaning. The stone covers of these mounds can still be seen in the ancient city of Jerash in Jordan.
It maintained a time until the modern civilization of the Romans developed. Construction began in Chicago’s sewers in 1856. At that time, New York City had only 200 miles (320 km) of sewers installed in 1870, compared to 6,200 miles (10,000 km) today.
The first manholes with lids could have been built in the early nineteenth century, not sewers, but with pipelines or pipelines. Up to now, no manhole cover of these manholes exists.
With some information about the history of the manhole cover, hope to help you relax.
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