4 car 150s are inefficient with four driving cabs when a 166 can hold nearly as many passengers. The guard also checks and issues tickets on these trains and three is easier than four.
Summer Saturdays at Paignton a ticket inspector would often be in one unit (especially when 143/150s) as far as Dawlish and the guard checking tickets and issuing tickets in the other.
The depot costing £40m is going to do more than clean trains. Also all the train staff are being moved to new accommodation in the office block to allow alterations to the station. Maybe extend platform 1 to take a 5 car 802. It can only take 4 cars at the moment.
From Rail Insider
In preparation for the depot receiving its first trains, Hochtief and Sheffield-based Mechan have worked together to design, build and install two 10-tonne powered turntables on roads leading to the depot’s bogie workshop and stores, to be used to transfer bogies between roads or to turn wheelsets around.
They have also installed a set of twelve 15-tonne lifting jacks, which can lift more than one vehicle type, to provide access to the underside of a train, without decoupling, saving valuable servicing time.