A 'signal controller' is installed on each street to manipulate traffic signals according to the situation.
If you operate this signal controller incorrectly, traffic could be paralyzed, so a lock was put in place to prevent anyone from touching it.
In addition, other traffic facilities, such as unmanned equipment boxes for traffic enforcement, are also opened with this key, and the Seoul Metropolitan Government said that it would prepare countermeasures in consultation with the police.
More details can be found on <SBS 8 News> on the evening of the 9th.