DCAN 11(Draft): Access for all - Designing for an Accessible Environment
Access to the Building
7.19 A level approach to a building i.e. an approach which is less steep than 1:20, should be used wherever possible. Where a change in level is unavoidable it should be made as gentle as possible, preferably with a gradient no steeper than 1:20. Short and shallow ramps minimise difficulties for wheelchair users and people with pushchairs for both ascent and descent, and reduce the likelihood of slipping for people with walking difficulties.
7.20 Ramp gradients should preferably be between 1:15 and 1:20. Ramps steeper than 1:20 should always have as an alternative, a flight of steps, for people who can more easily and safely manage steps. A gradient of 1:12 is the steepest permissible and should only be used if unavoidable. Stepped ramps (i.e. ramps broken at intervals by steps) are however unacceptable, as wheelchair users are unable to negotiate these without assistance.
7.21 A level platform at least 1.2 metres long clear of any door swing should be provided at the top and bottom of a ramp. Because frequent stops may be necessary to regain strength or ease pain, level landings are necessary. Ramps with a gradient between 1: 20 and 1: 15 should have a level resting point at least 1.5 m long, every 10 metres. Gradients steeper than 1:15 should have level resting points every 5 metres.
7.22 Ramps should be a minimum of 1.2 metres wide with an unobstructed width of at least 1 metre. 1.8 metres wide is preferred, as this would allow prams and wheelchairs to pass. They should be well lit and use non-slip surfaces. Patterning which simulates steps, such as applied or inserted slip-resistant strips should be avoided.
7.23 In general ramps or steps should be within the curtilage of the development and not encroach onto public footways. A ramped approach to an existing building can often be achieved by recessing the entrance door. Such ramps must not, however, project over adjacent pathways where this would be a hazard.
7.24 Where site characteristics prevent ramping it may be possible to raise the level of the external footway. If the area to be raised is on the public footway, this can only be undertaken where the agreement of DRD Roads Service has been given. Care will be needed to ensure that such an arrangement when provided for several nearby premises will not itself result in a hazard.
7.25 In the case of existing buildings where an extreme level change would require a long circuitous ramp, or where space is limited, a short rise lift may be appropriate.
7.26 Steps should be at least 1 metre wide and no more than 1.8 metres between handrails. There should be at least 1.2 metres of space at the top and bottom of flights clear of any door swing. A level platform should also be provided every 1.2 metre vertical rise of a flight of steps.
7.27 Steps should have a rise not less than 75mm and not more than 150mm and a minimum tread of 280mm. This is provided that the relationship between the rise and tread is that twice the rise plus the tread should not be less than 550mm and not more than 700mm. All risers and treads should be uniform in height and length. Tread nosings should be profiled so that they are not a tripping hazard for people at risk of catching their feet. Tapering treads and open risers are hazardous for blind and partially sighted people and should be avoided.
Figure 6: External steps
7.28 Corduroy tactile paving in a contrasting colour from the surrounding paving material should be installed at the top and bottom of a flight of steps (but not on the intermediate landings), to warn blind and partially sighted people of the change in level. The corduroy paving should start 400mm back from the nosing and should extend for a minimum of 800 mm.
7.29 The nosing of each step should be easily distinguishable for partially sighted people for example by use of permanent colour or tonal contrast.
7.30 Handrails should be 900 mm above the pitch line of a flight of steps or 1 metre above the surface of a ramp or the level of a landing. The handrail should extend horizontally at least 300mm beyond the top and bottom of the ramp or steps, with their ends clearly indicated by turning downwards or to the wall.
7.31 Even on a single step a handrail can provide essential support. Handrails should be smooth, continuous and easy to grasp (e.g. hardwood or nylon coated steel) with a maximum diameter of 38 mm -50mm and at least 45mm from any wall and colour contrasted with the background.