External stairs and ramps

Design away from the confines of the building envelope brings its own set of challenges. The first of these is scale. What might work inside won't necessarily work outside. Things need to be bigger to suit the scale of the space and this applies particularly to stairs. 

The second is topography as the environment is rarely flat. Unlike a building with set floor to ceiling heights, level changes between two surfaces outside are rarely the same. Therefore each external stair or ramp solution may be different. 

The third element is that most of the statutory codes and guidelines including the Building Code of Australia and the AS1428 series, apply only to new building works, not landscape works, and therefore it may be difficult to determine if you are providing a compliant landscape. Under the BCA it can be difficult to determine if an external stair is building-related or not, or required or non-required.

Principles

Four guiding principles are suggested for universal access.

1. Treat all people fairly and with dignity. While the Disability Discrimination Act 1992 makes it unlawful to discriminate on the grounds of disability, the concept of universal access also includes those without a disability, such as someone pushing a pram.
2. Look at ways to design out standards-induced clutter. The variety of different people's requirements for universal access can necessitate a lot of infrastructure to accommodate all needs, and this can be visually cluttering. For example, an access solution with a stair and a ramp will have handrails, kerb rails, stair nosings, tactile indicators, and associated luminance contrast issues. Where these can be replaced with a single walkway, much of this standards-induced clutter is not required and therefore is effectively designed out, thereby making a simpler landscape solution.
3. Consider access early in the design process. Access should be considered as early as possible in the design process. This is particularly important in establishing the entry points and floor levels for buildings, and the accessible environments around the building. Access solutions that are forced to work because due consideration wasn't given early enough are, more often than not, complicated and messy.
4. Aim for the best practical outcome. Aim to make the external environment as accessible as possible to maximize the experiences for the most number of people. As an example; for a remote visitor centre, where practical, the access from the car park to the building should be as universally accessible as possible. Similarly some of the key short walks should be designed to maximize the range of experiences available by being as universally accessible as possible. Refer to AS2156.1-2001 Walking Tracks Part 1 and Part 2.

Consideration of no stairs

For access to premises, the ideal situation is to avoid steps at the entrance. Careful consideration of the ground floor level and the relationships of entry doors to the internal and external levels is critical.

Where a building abuts the footpath, the location of the entrance doors must take account not only of the fall from the building to the kerb, but also any cross fall. To overcome cross falls it may be necessary to recess the entrance doors into the building. The public domain should not be the place where levels and access solutions are resolved.

Current stair provisions and guidelines

Other than for access to premises, there are no specific guidelines for designing external stairs. The closest guidelines are in the BCA and AS1428. It should be noted that the BCA uses the terms going and riser, where AS1428 refers to treads and risers.

Common problems with stairs, particularly in relation to access to premises include the following:

Too steep: This is a common problem. The BCA only covers stair treads associated with new building work. Stairs built to these ratios can seem steep and daunting in the landscape. What is acceptable in a building or a fire stair may not be appropriate outside. The maximum going of 350mm in the BCA is short of what is often required outside, where a 400mm or even 500mm tread may be more desirable. For example a 165x400mm stair feels very comfortable outside. When constructed as part of the landscape setting for a building, it may be necessary to show that such stairs are 'non-required' so that they can be built to a non-compliant ratio and signed off by the BCA consultant or certifier

Large stair runs: The use of landings can make the stair feel more welcoming and less daunting from the bottom.

Hand rails ending on the last step tread: A vision-impaired person may think this is the bottom of the stair and let go of the handrail and then may stumble, trip or fall as there is still one more step to the ground. If the handrail finishes short then it may also be too high for ambulant persons making it dangerous. Handrails need to extend one tread length then turn horizontal for 300mm before turning to the ground.

No handrail downturns: These can create hazards for children hitting their heads, particularly when they are looking down at the tread while their head is at the height of the handrail end.

Handrails on one side only: A stroke victim or an ambulant person with a disability with limited use of one side may be able to use the handrail going up but then not down the stair or vice versa. Central handrails on broad steps are an acceptable solution. In some instances the handrail will need to be double sided.

Tactiles on intermediate landings where there is a continuous handrail: To a vision-impaired person this can make it appear that they have reached the bottom of the stair, so they are not expecting the next flight of stairs.

Missing tactile indicators: Individual tactile dots and plastic strips can fail and dislodge. Plastic tactiles can fade externally and lose their luminance contrast.

Metal stair nosings pooling water: Applied metal stair nosings even with gaps left at the ends of treads can pool water, making steps slippery and dangerous.

Long runs of 'horse steps': These are stairs with long treads eg over 1m. They are sometimes used on shallow sloping ground to enable police horses to negotiate the steps. They can be particularly uncomfortable to walk on unless they have some shorter or longer landings that switch your gait around so you don't always hit a tread on the same leg.

Sloping ground against steps: It is not always possible to have a level bottom step outside due to sloping topography. In some cases a sloping bottom riser is the only available solution. Sloping risers are allowable, but can present a trip hazard, particularly when the tapered step height is lower than 50mm. It is desirable to minimize these thin wedges by truncating the tapering section of stair or providing some protection from it by way of a bollard, or handrail location. Where practical sloping risers should be avoided.

Step–sloping path combinations: Solutions which provide a sloping walkway diagonally through stairs create a lot of tapering steps.  A step-ramp combination is not possible because the handrail required for the ramp defeats the continuity of the adjacent stairs. Avoid where possible.

Ramps and walkways

Not all sloping pathways are ramps. Under AS1428.1 'Ramps' have a special meaning and special requirements which are different to 'Walkways'. Ramps are between 1:14 and 1:20 and walkways are shallower than 1:20 up to a gradient of 1:33. The confusion here is how you can have a 1:20 ramp and a 1:20 walkway. In essence you cannot have a 1:20 walkway, it has to be shallower.

Walkways tend to be simpler, as unlike a 'ramp' there are no requirements for handrails, kerb rails and tactile pavers.

Allowing sufficient space for ramps

The space required by a 1m high 1:14 ramp between two level areas is not 14m but 17m when intermediate landings, as well as handrail and tactile indicator overruns are considered. Where the ground at the top and bottom are sloping this becomes 17.6m so that there can be level landings top and bottom. Where level changes are lower than 642mm, the overall ramp length reduces by 1.2m as there is no requirement for an intermediate landing.

Handrails and balustrades

At present there are no specific external environment handrail and balustrade regulations. Where the external environment is part of an accessible path of travel or part of access to premises, then the requirements of the BCA and the AS1428 series need to be applied. However there are many situations where this is not the case or it is unclear. In this respect, specific value judgements and risk assessment needs to be made by the designer as to the application of the BCA and AS1428 to any proposed balustrades or handrails.  These documents do, however, provide guidance in the absence of specific standards.

By way of example, it is clearly impractical to fence off all falls greater than 1m in the environment, however, if you are deliberately taking people on a footpath to a dangerous location, eg a clifftop walk or scenic lookout, then the closest guideline for balustrades and fall heights is the BCA. In some cases a 1.2m unclimbable pool fence rather than the 1.0m BCA guide may be considered more appropriate. Similarly if a small set of rock stairs is used as part of an isolated bush walking track then it is reasonable to assume that, to be on this track, you would be able enough to not need a handrail.

Recommendations to architects

• Consider universal access as early as possible in the design stage. It can be hard to add on afterwards. Employ a specialist consultant to assist if necessary.
• Obtain accurate information regarding levels to enable the building entry to be located to maximize its ease of accessibility. Position doorways to minimize stair, ramps and pavement crossfall issues.
• Don't use the public domain to solve accessibility problems to a building when it should be undertaken within the building envelope.
• Plan level changes early and consider handrail overruns and landing requirements in the concept design stage for both stairs and ramps.
• Look at options to design out the need for standards-induced clutter. For example, where possible replace stairs with ramps. Replace ramps with walkways, replace walkways with universally accessible pavements.
• Provide as generous a tread ratio as possible in the external environment.

Additional information / References

• Building Code of Australia, clause D4 access and egress,Table D2.16a
• AS NZS 1428.1 2009, Design for access and mobility Part 1. General Requirements - New Building work,
• AS NZS 1428.2 1992, Design for access and mobility Part 2. Enhanced and additional facilities for Buildings. (to be discontinued)
• AS NZS 1428.4 2009, Design for access and mobility Part 4
• The Disability Discrimination Act 1992 Section 23
• Australian Human Rights Commission 2008 The good, the bad and the ugly – design and construction for access