Tuesday, December 24, 2013

CORRIDORS and PASSAGES as Transfer Systems in Buildings

Corridors and passages denote permanent transfer zones in buildings. These are usually well defined and functionally supported by other systems. However, when design definitions are improper, have inaccurate capacities or lose the validity due to the changed circumstances, not only the corridor but all other related systems become ineffective.

Corridors originate at points of transfer like doors, other branch corridors, stairs, elevators etc. Corridors also occur where conditions for superior and efficient transfers are available, such as: shaded or protected areas, finer floorings, smoother gradient, pleasant surroundings, promise of fulfilment, expectancy, escape from hazards.
Straight corridors provide a very efficient mode of transfer, but tend to be monotonous. Straight corridors allow continuous acceleration, which may pose problems to other transferee. Corridors with zigzag or variable movement directions heighten the expectancy. Circular or curved corridors tend to align the movement concentrically. Bidirectional movement corridors increase the social interaction amongst the users. Multi directional and multi velocity movements destroy the character of a corridor.

Corridors are heavy movement areas, so create a lot of noise and transmit pollutants. Corridors often enhance the fire hazards, spread of infections, and security risks; however, if properly designed corridors may curtail such risks. A straight corridor can be policed from one point, but so an intruder can command the entire corridor.

Corridors often have several services attached to them, such as: toilets, drinking water fountains, fire fighting systems, emergency exits, air handling units for air-conditioning systems, electrical mains, bulletin boards, exhibitions, first aids, security check-up systems, food and beverage dispensing systems, signs and graphics. Tirupati temple (India) corridors are also used by devotees as a place to sleep, rest, eat, bathe and pray by the devotees during the long wait for the Darshan.

In complex buildings variety of work spaces each with specific environment and controls are required; corridors help to create an intermediate or equitable zone of transfer for all such connected units. Corridors provide a strong cohesive identity among apparently very unrelated cells.

Corridors or passages defined and bounded by a barricade system only, require a minimum width of 630mm (such as bus stop queue passage) enforcing discipline, or nominally 800mm for one person wide queue. Enclosed corridors or passage, as suggested in most residential building bye-laws, should be minimum 900mm wide for short length runs of 5mts. For greater lengths a width 1200mm is advisable. For wheelchair traffic minimum 1000mm width in straight sections, and more in angles or curvatures, is required. Where movement is likely to be intense, bidirectional and with hand carried luggage a width of minimum 1500mm should be provided. Where corridors are likely to be 1500mm or less in width, the doors should be placed in a recess, and must open away from the corridor space. Preferably doors should not open out into the corridors unless a recess equal to the full swing of a door shutter is provided. Opposite doors on a corridor should be preferably staggered. At all the end, start or junctions, there should be no door opening for a length equal to the width of the corridor. Cross corridor junctions must happen in a wider lobby or foyer. Corridors should have a secondary escape point for every length section beyond 15mts. Very long corridors tend to be boring so should intermittently terminate into a hall or foyer before being continued.

There should not be any projections or fixed or loose furniture in the functional width of the corridor. Where visually impeded people are going to transit, the projection off the wall must not be more than 100mm, and furniture including the space for knee or leg of the user must be accommodated in alcove or niche.

Illumination in corridor needs careful planning. Windows at the end of a corridor, or doors on corridors opening out to an exterior, create a glare. Artificial compensative illumination is very necessary to counter the glare. Openings on the sides of a corridor provide a visual distraction, but unless fairly intermittent or properly designed, create a very patchy lighting. Wall mount illumination fixtures and ceiling spots fail to provide the desired effect when corridor height is low and traffic density high. Illuminated ceilings provide very poor modelling and social recognition. In such situations lighter colour scheme and indirect glow not only on ceiling but  upper section of the side walls helps. Illuminated steps and side hand rails provide a functional definition. Illumination level in corridors should never be consistent as it creates boredom, It should be high enough near openings to counter the glare and in some situations (drama auditorium) even feeble in contrast to the interior. Illumination fixtures that are visible like shaded lamps, diffusers, chandeliers etc. create a visible physical dimension.

Paintings on corridor side walls
must be smaller and with greater details that can be enjoyed at a closer distance (often less then 450mm) such as Indian miniature paintings. Large paintings with very extensive colour or form patches are hardly visible in a corridor like narrow space. Passages, (unbounded corridors) require side edge definitions. Such definitions could be in terms change in flooring colour, texture or pattern if the traffic density is low. Alternatively definitions could be through change in the floor level or side barricading at 800mm to 1200mm level. The barricades could be ceremonial or representative only. The barricades could also be intermittent like planters, boxes, ash-posts, poles, etc.

Passage and corridors carry services such as ducts, wires, etc. To manage these often a cover like a ceiling is required. The ceiling is designed to absorb the locally generated sound, and also mask the sounds that leak  out from the rooms, through the crevices along the installed services.

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