Also why are there two painted bands? One at roughly head height and one at chest height. Is it a precision thing?
Keep looking, and it seems a lot of them are dark blue.
Blue again at Grove Park, which like Chislehurst is on Southeastern. But also blue at Hounslow and at Malden Manor, both of which were once Southwestern.
And not just in London.
Here are blue stripes on a white pillar at Christchurch and white stripes on a blue pillar at Stockport. White stripes again at Hartlepool... but now seemingly no consistency in height.
You can also see them on the London Underground.
White on green at Hornchurch, but dark green on light green at White City. Meanwhile at Southfields some bands are white and some are grey.
And it can't be a heritage thing because these next three stations are really new.
I had a dig and it's an accessibility thing. If you're partially sighted a free-standing post or column is easy to miss and can cause a nasty injury. So a contrasting band (or two) is added somewhere near eye height to maximise the chance it'll be spotted.
I found these in station guidance:
• Necessary free-standing items such as columns should have adequate tonal contrast with the floor colour and the background they are seen against. They should also incorporate a 150mm wide tonally contrasting band with the bottom edge at 1500mm above the floor.
• Any free-standing post or column within an access route should incorporate a band that contrasts in colour and luminance with the remainder of the item. The band should be a minimum depth of 150mm, placed with the lower edge of the band between 1400mm and 1600mm above ground level. Some guidelines advocate deeper bands or more than one band, but the single band (minimum 150mm) is acceptable to the RNIB.
• It is recommended that upright posts, grabrails and pillars be of a contrasting colour to the surrounding platform surface. Where this is not possible, they must be marked with a contrasting coloured band 140–160 mm wide, with its lower edge at 1500 mm from the ground. An additional lower band should also be used to mark them as a hazard.
It's called DDA banding, and once you start seeing it you see it everywhere.
