(15 Sep 2015, 10:32 pm)BusLoverMum wrote I think it's a service where they simply need to ensure the right buses are on at the right times. It travels fairly light, quite often.
On weekdays the Enviro 400s are on the same runs each day which are the busiest runs of the day for morning and afternoon loadings, during the daytime you'll only see small handfuls of passengers upstairs, there isn't really any need for full double deck operation on the 7. I think they may also be allocated for certain workings so they don't stay out on a night.