Why is the manhole cover round?

The reason is also closely related to mathematics.

First, the manhole is located on the main road, and people come and go every day. Attention should be paid to the safety of pedestrians when designing, and the manhole cover should not fall into the manhole. If it is designed as a triangle or a square, although the cover is larger than the manhole, it may still fall down. And if it is round, because the diameter of the circle is equal, the cover will not fall off as long as it is slightly larger.

Secondly, because the manhole sometimes needs manual combing or threading, the area of the manhole is required to be as large as possible at this time. In these figures, when the perimeters are equal, the area of the circle is the largest. At the same time, the circle conforms to our body shape, which is convenient for staff to go in and out.

Thirdly, the sides of a triangle or square are composed of straight lines, forming an acute angle, which is easy to hurt people if touched during maintenance. And the edge of the circle is an arc, so this problem will not appear. These manhole covers, which are engraved with Shanghai classic buildings, bear the mission of municipal engineering and are filled with a strong humanistic atmosphere, adding an elegant Shanghai style to Nanjing Road Pedestrian Street, and also adding an unexpected surprise and humanistic enjoyment to tourists who inadvertently discover the unique scenery under their feet. I believe that more and more manhole covers full of humanistic flavor and taste will appear at the feet of Chinese people and jump into their eyes.

There are many kinds of manhole covers, but manhole covers are almost "one side of a thousand cities", mostly black iron covers. In recent years, in order to prevent theft, most of them have been replaced with gray cement covers. Whether it is an iron cover or a cement cover, there is no logo, or the word "sewage" can be seen occasionally. Only on the manhole covers made of some new materials recently, the words "rainwater", "water supply" and "telecommunications" rarely appear. Even so, the appearance of the manhole cover has not changed much, and the costume of the ancestors is still used.

The original function of manhole cover is to shield the reserved holes for underground pipeline maintenance, which is the first and most fundamental function for engineers to enter and exit. Therefore, when considering improving the "humanistic taste" of the manhole cover, we must not give up everything, forgetting that the setting of the manhole cover should first be easy to manage and maintain. Each manhole cover should be clearly marked with its category in a conspicuous position, so that managers and maintenance personnel can know the network management category under the manhole cover for the first time.

Because of this, when people are delighted with the manhole cover engraved with classic buildings and full of humanistic atmosphere on Nanjing Road Pedestrian Street, they have to regret that it failed to fulfill its duties. Because these elegant manhole covers just lack functional signs. Those manhole covers with different customs in Japan and Europe and America have not been defiled by the word "function". In people's consciousness, the manhole cover is first of all the cover plate of underground pipe network, not a simple work of art, and the extra patterns on this basis give people unexpected surprises and sensory enjoyment, which is second. In other words, no matter how beautiful and tasteful the manhole cover without functional identification is, it is no longer a real manhole cover. Of course, we can also consider using Chinese Pinyin to express functions, so as to avoid the suspicion that words such as sewage are unsightly and achieve the best of both worlds.

The cultural taste of manhole covers is second, but this does not mean that it can be ignored. On the contrary, with the improvement of people's living standards, the requirements for cultural taste will be higher and higher. Therefore, it is necessary to pour more wisdom into improving cultural taste. For example, the newly-built manhole cover on Nanjing Road Pedestrian Street, it seems that the return rate of tourists is not high at present, and many tourists have not found a new atmosphere at all. On the one hand, the dazzling array of goods on both sides of the road attracts tourists' attention; On the other hand, the single color of the new manhole cover is too harmonious with the color of the road surface, which is also an important reason for not attracting attention. It is not difficult to imagine that if the manhole cover engraved with Shanghai classic buildings uses bright colors completely different from the surrounding roads, and the pattern itself uses bright colors as much as possible, the chances of tourists seeing it will be greatly increased.

Here, I have to mention another fly in the ointment of these manhole covers engraved with Shanghai classic buildings on Nanjing Road Pedestrian Street: when people appreciate these classic buildings, they often naturally want to know their surnames. Because people may not know every building in detail. Therefore, if the names of buildings can be marked together, people can better understand the urban culture of Shanghai. On the other hand, if the manhole cover has more practical functions, its attraction will be greatly improved. For example, learn from the practice of some places in Japan, and mark road signs and regional maps on manhole covers, especially in areas where foreign tourists account for the vast majority, such as Nanjing Road Pedestrian Street. You can use manhole covers widely distributed on sidewalks to mark the locations of toilets, subway stations, banks, restaurants and other facilities, giving manhole covers more "humanistic atmosphere" and "human touch" and enhancing urban culture.

From this perspective, there is actually quite an article on the manhole cover. By expressing functions on the surface of the manhole cover, engraving excellent urban buildings, portraying urban cultural characteristics, and indicating road signs and public facilities, the originally humble manhole cover can integrate various functions such as municipal facilities, cultural heritage and public services, and become an indispensable warm existence in citizens' lives. Huang Wei/Wen There are various manhole covers in Europe and America. In these countries, manhole covers play a versatile role: they not only remind and protect the entrances and exits of manhole covers, but also beautify the urban road landscape. There are many multifunctional manhole covers in the city, which are marked with the words "rainwater", "sewage", "water supply" and "telecommunications" respectively. Some signs indicating public facilities, blocks and scenic spots are placed on the manhole covers located in pedestrian streets to guide people to their respective destinations.

In some places, the "retired" manhole is even reused, re-planned and redesigned for people to visit, which has become a nostalgic urban landscape and left endless memories for people and tourists. In some communities, manhole cover culture has become an important part of the life of community members. At a certain time every year, everyone will spontaneously organize and beautify the manhole cover of their community by "graffiti". In Asia, Japanese manhole covers have a strong cultural charm. Every manhole cover in Japan is marked with the words "rainwater", "sewage", "water supply", "telecommunications" and "fire protection". The biggest feature of Japanese manhole covers is originality: manhole covers in every county, even city and district have local characteristics, which are unique and full of rural charm. Conceive the manhole cover pattern with local scenic spots, city flowers, city trees or specialties, and highlight local characteristics. On these lovely patterns, there will be various descriptions, such as the types of manhole, the traditional culture of the block, the orientation of tourists, the surrounding environment and so on. And sometimes there are some advertisements.

It is particularly worth mentioning that there are no fire hydrants on both sides of roads in Japan, and all fire hydrants in Japan are protected under manhole covers. Just open the manhole cover when using it. In order to highlight the location of the fire hydrant, this manhole cover adopts eye-catching colors, such as yellow and blue. It is strictly forbidden to park and pile things above the yellow or blue manhole cover to ensure that it can be put into use immediately in an emergency.

In recent years, many colleges and universities in China have carried out the beautification project of manhole covers, among which the beautification activity of the School of Architectural Art and Design of Liaoning University of Science and Technology has achieved great social and public welfare effects, which not only adds beautiful landscapes, but also plays a role in reminding pedestrians to pay attention to safety.