roadman = black
chav = white
chav is fading out now
some non black people can get away with looking like a roadman instead of a chav by wearing "trendy" gear like palace x adidas, huaraches, supreme, skinny jeans or anything skepta has worn.
Can't speak for other cities or towns, but it's local slang in London. You won't really hear it outside of the less affluent areas of places like southwark or tottenham. very prevelant on this side (south of the river) for a long time, only been co-opted my middle class white trash somewhat recently