If you travel on the sub-surface lines, you might not be aware of it, but the trains have a small point of interest in their door design.

It’s only a minor issue, but the front and rear pair of doors are noticeably smaller than the rest of the train.

Compare below:

The smaller doors are 1.2 metres wide, while the rest of the doors on the S-Stock trains are 1.9 metres wide.

It’s a small thing, but in an odd way, on a train that is otherwise totally uniform in design and appearance, to know there’s this slight difference to the uniformity at each end is strangely pleasing.