study notes vertical circulation

UNIT 4: VERTICAL CIRCULATION IN EARTH STUDIES 220

1. INTRODUCTION

• Unit 4 focuses on vertical circulation, addressing how structures accommodate changes in elevation in both external and internal environments.

• Key access features studied include:

  • Ramps

  • Stairs

  • Handrails

  • Lifts

1.1. Unit Outcomes

• After completing Unit 4, students should be able to:

  • Explain the functional needs that determine the inclusion of the following access features:

  • Ramps

  • Stairs

  • Handrails

  • Lifts

2. RAMPS

• Ramps serve as an alternative means to overcome level changes and are essential for individuals using wheeled assistive devices as well as those who find stairs difficult or hazardous.

  • Importance for persons with hearing disabilities who lip-read or use Sign Language (SASL), as ramps facilitate conversation during ascent or descent.

  • Ramps are NOT a replacement for stairs, as some people with disabilities may also find ramps challenging to use.

  • Ramps should align with other vertical circulation methods (e.g., be near main entrances and position in pathways).

  • Providing both ramps and stairs offers users a choice to navigate level changes safely and comfortably.

2.1. Gradient

• A safe and dignified independent usage gradient is between 1:15 and 1:20.

• In restricted spaces, gradients must not exceed 1:12 (SANS 10400-S 2011: 17-18).

• Wheelchair users often have limited upper body strength; gradients steeper than 1:12 (e.g., 1:10) are tiring and may risk the user’s safety.

• A wheelchair weighs between 14 kg and 31 kg, complicating self-propelling up or controlling descent on steeper gradients.

2.2. Orientation

• Ramps must be located so that users can enter buildings through the main entrance alongside other users.

2.3. Calculating Gradient and Length

• The objective is to provide ramps with both the shortest distance and safe gradient (ideally 1:15 to 1:20).

• Important calculations include:

  • A 1:20 gradient implies that for every 1 m vertical rise, 20 m of ramp length is required.

  • With added landings (top, bottom, and one mid-point), 24.5 m of ramp length is necessary.

  • Calculations must consider the optimum gradient and available space, included in the ramp layout and design documentation.

  • Detailed drawings must feature longitudinal sections illustrating level changes, ramp length, gradients, landings, and handrails.

2.4. Width

• The minimum clear width of ramps per SANS 10400-S should be 1.1 m.

  • This width is insufficient for two wheelchair users to pass; hence, a recommended width of 1.8 m allows for safe passing.

  • A width between 1.5 m and 1.8 m permits both wheelchair and walking individuals to navigate together comfortably.

2.5. Landings

• Level landings must be included at:

  • The top and bottom of the ramp

  • Every directional change

  • Regular intervals (see Table 2.1 for specifications).

• Landings should allow sufficient space for wheelchair users to stop, open doors, and turn around without rolling back along the ramp.

• Minimum landing length must be 1.2 m clear of door swings, and widths should match the ramp width.

• The recommended wheelchair turning circle diameter is 1.5 m for adequate maneuverability.

2.6. Handrail and Kerb

• Handrails are essential for users who may need extra support, particularly those with unilateral weakness or balance issues.

• Design requirements for kerbs and balustrades include:

  • Minimizing the risk of wheeled traffic running off the ramp.

  • Preventing wheelchair users from entrapment of feet or equipment between balustrades.

  • Allowing emergency braking or resting options.

• Kerbs should be made from solid materials (e.g., brick, concrete) with a minimum height of 75 mm.

2.7. Surface

• The ramp surface must be firm, smooth for mobility ease, and non-slip in wet and dry conditions.

3. STAIRS

• Stairs are the primary vertical circulation method and emergency escape route.

• People with disabilities often use stairs. Design considerations should include:

  • Low risers and wide treads for people with walking impairments.

  • Adequate width to allow safe passage between users.

  • Requires proper accessories such as handrails on both sides.

  • Good lighting levels, particularly outdoors, to enhance safety in low light.

  • Design must comply with SANS 10400 Parts M, T, and S.

3.1. Treads and Risers

• All stairs must have uniform width and height for treads and risers:

  • Minimum tread width: 250 mm (SANS 10400-S 2011: 19).

  • Preferred range for external treads: 280-300 mm; internal treads: 250-270 mm.

  • Maximum riser height: 170 mm (SANS 10400-S 2011: 19).

  • Avoid open risers due to associated hazards; they can cause visual confusion and present trip risks, especially for individuals with injuries or visual impairments.

  • Recommended maximum riser height for external stairs is 150 mm and for internal is 170 mm.

3.2. Nosings and Nosing Strips

• Design considerations for nosings include:

  • Rounded or chamfered, avoiding overhangs that create trip hazards.

  • Uniform color may confuse visually impaired users; it is critical to highlight risers and treads with contrasting colors and textures.

  • Nosing strips should be about 40 mm x 40 mm to assist blind and partially sighted individuals.

4. HANDRAILS

• Primary function: Provide essential support when ascending or descending stairs and ramps.

• Handrails must be included on both sides of ramps and stairs, regardless of the number of steps or slope.

• Specifications for handrails include:

  • Must be securely fixed and rigid to support a full body weight.

  • Continuous through landings for clear navigation.

  • Extend 300 mm beyond the top and bottom of stairs or ramps for tactile guidance and balance assistance.

  • Height should be in the range of 900-1000 mm, with 900 mm preferred for shorter individuals, children, and wheelchair users.

• Shape should allow a natural grip, optical diameter of 35-50 mm, with clear space from adjacent walls (60 mm).

5. LIFTS

• Lifts are often the most convenient travel method between building floors for those unable or unwilling to use stairs.

• Essential specifications include:

  • At least one lift must accommodate a wheelchair and have access to key areas (lobby, corridors).

  • Consider lift utilization during evacuations in new building designs.

  • Lifts should be positioned adjacent to staircases for alternatives to users who prefer stairs.

5.1. Internal Dimensions

• Minimum lift dimensions:

  • Width: **1.1 m

  • Depth: 1.4 m

  • Doorway needs to be at least 800 mm unobstructed (SANS 10400-S 2011: 21).

• Larger lifts (preferably 1.8 x 1.8 m) are recommended to enable better mobility for wheelchair users and anyone with prams or scooters.

5.2. Lift Controls

• Operating buttons should have letters raised 1 mm above the surface, contrasting with the background, or illuminated for accessibility.

• Buttons should provide positive feedback when pressed, such as illumination.

• Clear auditory signals, such as a voice announcing floors, are essential for visually impaired users.

5.3. Emergency Systems

• Safety device reach should accommodate wheelchair users.

• Emergency systems must include visual signals for the deaf and tactile instructions alongside visual forms.

5.4. Internal Finishes

• Floor Surface: Should be matt, firm, non-slip, and should not be dark to avoid misinterpretation of lift fit.

• Visual Contrast: Important for assessing lift dimensions, with surfaces kept matt to reduce glare.

• Mirrors: Should help users see behind; full-height mirrors are discouraged to avoid confusion with passages.

• Lighting: Evenly distributed for visibility with a target illumination level of 100 lux.

• Handrails: Required on all internal lift walls (900 mm above the finished floor) for user support.