How many metres distance from the preceding vehicle should you maintain when stopping in the tunnel due to a traffic jam?

In accordance with the Road Traffic Act, a driver in a tunnel, when stopping due to traffic conditions or regulations, is required to maintain a distance of not less than 5 metres from the preceding vehicle. The traffic congestion visible in the photograph is precisely such a situation. Maintaining this distance is intended to ensure safety and, for example, to allow access for emergency services in the event of an accident.