Return of the Roadworks

After the mixed results that met their first attempt to mess up the traffic in Worcester Park the two fine men assigned to this important task are having another crack at bringing work to underemployed psychotherapists and anger management counsellors of the area. Anyone know why the magic number for workmen seems to be set at two? Is there some complex algorithm at work that means that having more than two would cause twice the congestion... or halve it...