Every day we encounter this piece of urban infrastructure and do not notice it, and in vain!
井蓋
scheme of the sewer manhole cover with the most common form
But covers can be regarded not only as a technical urban attribute. Many cities use manholes as a visual communication with local residents and tourists.
Sewer manhole cover — a part of the manhole, installed in the manhole body.
Saint-Malo
BUDAPEST
SEVASTOPOL
CHINA
MONTREAL
BRATISLAVA
Why are the manhole covers round?
圓形
rectangle
Sometimes you can really find hatches of an interesting shape: square, rectangular, and even the Reuleaux shape.
Reuleaux shape
square
一
But the most common is the round shape of the lid. And here's why:
The cost is going down
The round shape of the cover reduces the internal forces that occur when it is loaded, thus minimizing its thickness and the cost of materials.
二
it Reduces rejects
By reducing the length of the supporting parts, the probability of defects (protrusions, etc., which leads to "slamming" of the lids when they collide with them) is reduced.
三
Convenient transportation
The heavy weight of the hatch makes it quite heavy to carry by hand. The round shape of the hatch allows it to be rolled.
四
The cover does not fall
Rectangular cover easily fits into the hatch body diagonally.
How 240,000 covers were stolen in one year in Beijing
盜竊
收藏家的滅亡
Why do they "steal" the covers?
In 2004 there was a surge of manhole cover thefts in China and around the world. James King, former bureau chief of the Financial Times in Beijing, describes the phenomenon in his book China That Shook the World
一
for subsequent resale as scrap metal
三
for sale, or are stolen by collectors themselves
in order to use it "at home", for example, in the countryside
Vadim Shefner's fantasy story "The Death of a Collector" describes the vast gallery of sewer manhole covers that make up the collection of one of the characters.
二
In the weeks since mid-February 2004, when, slowly at first, but with increasing speed, manhole covers began to disappear from roads and sidewalks around the world. As Chinese demand for metal raised scrap metal prices to record levels, thieves almost everywhere guessed at the opportunity to make money from manhole covers. As darkness fell, they dragged the hatches and sold them to local businessmen, cut them up and loaded them onto ships bound for China. The disappearances were first seen in Taiwan, on an island off the southeastern coast of China. Then at other neighbors, such as Mongolia and Kyrgyzstan... Where the sun went down, thieves worked to quench China's need for metal. More than 150 manholes disappeared in one month in Chicago. In Scotland, more than a hundred manholes disappeared in a matter of days. From Montreal to Gloucester to Kuala Lumpur, unsuspecting pedestrians stumbled across holes in sidewalks.
Even though the situation has been brought under control, all of us are now faced with open manholes without a cover from time to time.
In the weeks since mid-Feb-ruary 2004, when, slowly at first, but with increasing speed, manhole covers be-gan to disappear from roads and sidewalks around the world. As Chinese demand for metal raised scrap metal prices to record levels, thieves almost everywhere guessed at the opportunity to make money from manhole covers. As darkness fell, they dragged the hatches and sold them to local businessmen, cut them up and loaded them onto ships bound for China. The disappearances were first seen in Taiwan, on an island off the southeastern coast of China. Then at other neighbors, such as Mongolia and Kyrgyzstan... Where the sun went down, thieves worked to quench China's need for metal. More than 150 manholes disappeared in one month in Chicago. In Scotland, more than a hund-red manholes disappeared in a matter of days. From Mont-real to Gloucester to Kuala Lumpur, unsuspecting pe-destrians stumbled across holes in sidewalks.
The dangers of open manhole, and what to do if you notice a missing cover?
危險
What should you do if you encounter an open manhole?
This applies not only to manholes in the sidewalk area. Often on roads, cars damage their wheels by hitting a manhole, which can also lead to an accident as well.
Every year there are dozens of unfortunate cases involving manhole covers. In some cases, you can get away with a fright, but in others, everything is much more serious.
Even though the situation has been brought under control, all of us are now faced with open manholes without a cover from time to time.
二
Specify address
If there are no signs, try to find out the exact address where the well is located. Find on the Internet the contacts of the housing maintenance company responsible for the area. Tell them about the open manhole.
一
Find the symbols
Determine who owns the sewer manhole. You can find this out only by the symbols on the manhole cover.
三
Make a fence
Make a fencing or warning structure:
Tie a brightly colored bag or rag to the branches;
to put branches or planks into each other and into the asphalt around the manhole to make a "house";
put planks or plywood on the hatch;
put an old tire, etc;
stick a long branch or board into the well at an angle.
艙口蓋藏著什麼
What are the manholes hiding?
秘密
When we think about what's on the other side of the manhole cover, we all think of different images, from Ninja Turtles to movies about robberies and escapes through sewers. What's really there?
distribution equipment or control mechanisms of the piping systems passing through here,
locking knots with metal circles resembling naval steering wheels,
some small cells,
pipes.
Manhole manhole can lead to a shallow depth, and can rush
to 52 meters below ground level, such as
in the under-construction sewer
in Saratov, or reach 200
meters as in the
Third tunnel
water
supply
of
N
e
w
Y
o
r
k
.
to 52 meters below ground level, such as
in the under-construction sewer
in Saratov, or reach 200
meters as in the
Third tunnel
water
supply
of
N
e
w
Y
o
r
k
.
In the underground depth, depending on the type of sewer well, there may be:
Manhole manhole can lead to a shallow depth, and can rush to 52 meters
below ground level, such as
in the under-construction
sewer in Saratov, or
reach 200 meters
as in the Third
tunnel
water
supply
of
N
e
w
Y
o
r
k
.
below ground level, such as
in the under-construction
sewer in Saratov, or
reach 200 meters
as in the Third
tunnel
water
supply
of
N
e
w
Y
o
r
k
.
Manhole
covers are not only an attribute of the city, to which we are all so accustomed that we sometimes do not notice.
{which is very dangerous!}.
covers are not only an attribute of the city, to which we are all so accustomed that we sometimes do not notice.
{which is very dangerous!}.
結論
It is also a subject of art, design and inspiration. Just look at this beauty :3
and
look down
at
your
feet
.
look down
at
your
feet
.
