What time of the day was it? If it was early morning or rush hour then they were not the cause of the traffic. Probably looking for drivers on their mobiles/cars that raise a flag on the system.
it was morning rush hour - which is usually bad enough - but just sitting on the side of the road is enough to add an extra 15 to 20 mins to the normal 20 minutes to get from J9 to J7.
