The intention to carry more passengers in a train of the same length as other contemporary stock was met, with the two 4-DD units having 1,104 seats compared to 800 in other units of similar age. However it was found that the additional number of passengers meant longer time spent at stations to allow passengers to get on and off. In practice, the upper compartments were cramped and poorly ventilated because the upper level windows were impossible to open due to tight clearance. To resolve this problem, the compartments were pressure-ventilated, but the equipment proved to be unreliable.