Building owners in major cities around the nation are suspending use of revolving doors and checking them for safety following the death last week of a 6-year-old boy at the Roppongi Hills complex in Tokyo and revelations that 32 similar accidents have taken place at the site since it opened last April.
While the police investigation has focused on the Roppongi door’s sensor system, the accident has also raised the question of why these potentially hazardous doors have become so popular.
According to Tokyo Metropolitan Government officials, there are at least 260 automatic revolving doors in Tokyo, most of which are less than three years old and are installed at hotels and high-rise office buildings.
One main reason for their popularity is that the doors block entry into buildings of strong drafts generated around skyscraper entrances, said Masatoshi Hirano of the metropolitan government.
Should air pressure surge inside structures, doors on upper levels may slam shut, experts say.
Mitsubishi Estate Co., which announced Tuesday it was suspending operations of all 19 revolving doors at the buildings it owns, also said wind is a big reason for installing revolving doors.
“For high-rising buildings, updrafts pose the biggest problem,” said Mitsuo Iwai, executive officer of the major real estate firm.
Energy costs are another concern, Iwai said. Because revolving doors prevent outside air from coming into buildings, they help keep air conditioning costs down.
The Osaka branch of the Takashimaya department store chain said it has used its four revolving doors only in summer and winter, when temperature differences between indoors and outdoors are significant or when there is a strong wind. It has suspended use of the doors since the Roppongi Hills accident, said spokeswoman Hikaru Kakiya.
But perhaps the biggest — and least publicly stated — reason for the popularity of revolving doors is their high-class image, experts said.
“Everyone who has watched Hollywood movies from the 1950s or 1960s is familiar with them and feels excited to see them,” an architectural expert said.
An official of Yokohama, where revolving doors at Landmark Tower have caused injuries, likewise said appearance is a major reason firms have installed automatic revolving doors in recent years.
“I would say it’s a design issue,” said Genshu Wakatsuki, an official in charge of construction management. “Not all designers want to use the same entrance style.”
The Tokyo Metropolitan Government has instructed revolving door manufacturers to conduct safety checks on their products.
It said it is waiting for safety guidelines to be issued by the Land, Infrastructure and Transport Ministry before taking further action.