What do the raised bumps on pavements at Northern Ireland crossings mean?

They are tactile paving designed to warn and guide blind or partially sighted pedestrians.

Under Highway Code rule 10, raised studs often identify a crossing point with a dropped kerb; rounded bars can mark steps, level crossings and other hazards. Do not obstruct tactile paving with bicycles, scooters or parked vehicles. Different patterns carry different information rather than being purely decorative.