The new rule should provide clear instructions for motorists: at present some are hesitating about what to do when they hear the siren of an ambulance or a police car behind them. Some start to panic, and block the way through instead of creating the extra space.
Whenever you end up in a traffic jam - or whenever the speed is reduced to 10 miles per hour - leave enough space for another vehicle to pass by keeping as much to the left as possible on the left (fastest) lane. Motorists on the adjacent lane to the right, will switch to the right as much as possible. This system already exists in other countries where it has proved its worth. (watch a German instruction movie below)