Design considerations for ramped approaches with complementary steps

Visually impaired people risk tripping or losing their balance if there is no warning that there is a change in level. Tripping is most hazardous at the head of a flight of steps when a person is descending. The warning should be placed sufficiently in advance of the hazard to allow time to stop and not be so narrow that it might be missed in a single stride. People who wear callipers or who have stiffness in hip or knee joints are particularly at risk of tripping or catching their feet beneath nosings. People with a weakness on one side or with a sight impairment need the dimensions of the tread to be sufficient for them to be able to place their feet square onto it. If the going is towards the upper end of the dimensional range, the flight may rise to a greater height without the need for an intermediate landing, as the tread is sufficiently deep to allow a person to stand and rest at any point within the flight. Where complementary steps and a ramp share a surface containing their respective notional landings, it is preferred that the tactile warning surface be located clear of the ramp landing.