In order to eliminate hidden safety hazards in life, many clever designs have appeared. For example, some household appliances will power off after being dumped; some bottles for prescription drugs have a special design: they must be pressed and rotated before they can be opened, and children will not open or take them by mistake.
In order to reduce the use of straws, the lid of the disposable coffee cup has a small mouth for direct drinking. But some clever designs will not be immediately accepted by people. American podcast host Roman Mars said in the book "99% of the invisible cities" that the first use of the revolving door was a restaurant in New York. Its inventor, Cannell, said that the advantage of this kind of door is that it will not forget to close, will not be blown open by the wind, and will not be closed by anyone. It can be on and off at the same time. When people come in, there is always a door to keep out the wind.
Studies have shown that the air circulation of an ordinary door is eight times that of a revolving door. The revolving door can save $8,500 in air-conditioning costs each year. The electricity saved by using the revolving door can make a 60-watt light bulb light up for 23 minutes. But about two-thirds of people don't like to use a revolving door, because sometimes they have to push it to rotate or worry about being caught in the body. The revolving door has the advantage that everyone enters and exits from the right side in turn, and will not collide with oncoming people. It also reduces the need to help others open the door and block the door. But it has a flaw. During World War II, 492 people were killed in a fire in a nightclub in Boston. Everyone was blocked at the door. If they wanted to go out from both sides of the revolving door at the same time, the door could not be turned. Therefore, most buildings now require ordinary doors to be installed on both sides of the revolving door.
There are various pipes and wires below the city. In order to prevent being dug, there will be a unified bright reminder sign above. In 1976, a construction accident occurred in California, which caused an explosion to flatten half of the buildings in a block of a city. Since then, the United States has designed a unified color warning sign. For example, red represents wires and pipes, orange is telephone lines, yellow is natural gas, green is drainage system, blue is drinking water, purple is reclaimed water or irrigation water, pink is temporary sign, and white is excavation area.
There is an "Excavation Warning" organization in Los Angeles. Anyone who implements excavation operations in Los Angeles must mark their work areas with white paint, chalk or flags, and contact the "Excavation Warning" organization, which will mark the location and depth of the things below. A radar that can penetrate soil can detect metals and magnetic fields, help find cement pipes, plastic pipes and electrical wires, and then mark them with colored symbols.
Mars also explained why the manhole cover is round: the round manhole cover will not fall like a square or oval manhole cover when it is turned up, and it can resist the pressure in a balanced manner. The uniform round frame is also easy to manufacture. If the round manhole cover is heavy, it is easy to move: it can roll along the road when it is turned over. There is also an awl-shaped manhole cover in Japan, which shrinks from top to bottom, like some bottle stoppers. The advantage of this kind of manhole cover is that when a car passes by, they shake less, thereby reducing noise pollution. In some places prone to floods, the manhole covers are fitted with hinges.
Interestingly, not all designs are designed to make people's lives more comfortable. For example, the speed bump on the road prevents the driver from driving at high speed comfortably. Some chairs in public places are as uncomfortable as possible, and they don’t want someone to occupy them for a long time and sleep on them. Therefore, some benches have armrests in the middle, and there is a place to put their hands, but people cannot lie on them to sleep. British travel writer Bill Bryson couldn’t afford to stay in a hotel and spent the night on Dover’s seafront promenade. “The bench was covered with slats, it was hard, and it was knocking on big screws. Possibly-there is no doubt that this is intentional."
The chairs at the bus station do not have a backrest and are highly inclined, just because they don’t want people to sit comfortably for long periods of time. There are also rumors that the chairs of some fast food chains are only suitable for people to sit for fifteen minutes. In some places, you can't see the chairs after walking for a long time. It may be because people are not welcome to stay. At this time, people will use other designs: folding stools, picnic mats.
