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Post -767 –by Gautam Shah
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Revolving door, is an American innovation for an entrance system for foyers or lobbies of public and commercial buildings. A German, H. Bockhacker of Berlin, in 1881, was granted a patent for Thür ohne Luftzug (‘Door without draft’ of air). In USA, of Philadelphia, Theophilus Van Kannel was granted a patent in 1888, for a Storm-Door Structure (to exclude noises from the street). The patents did not, however, use the term ‘revolving door’. It is claimed that worlds’ ‘first’ wooden revolving door was installed at Rector’s restaurant on Times Square in Manhattan.
Revolving doors have nominally 3 or 4 leafed or winged shutters. The shutters rotate by maintaining their fixed position (120° or 90° angles) on a central shaft. Actual passage width or accommodation is determined by the number of wings and the diameter of the drum within which the shutters rotate. The shutter side edge and inner surface of the drum are fairly tightly packed to prevent passage of air and sounds. The system was intensively marketed as ‘doors that always remain closed’. It was also publicized with curious words such as ‘as capable of avoiding the noxious effluvia and baleful miasmas’. In other simpler words the doors were supposed to save life, ‘by preventing lung and throat infections (diseases)’.
There are many issues with passage accommodation through the revolving doors. These relate to carrying bags in hand, assistant supporting infirm people, walking stands, wheel chairs, patient stretchers, strollers, luggage racks (hotel lobbies) and trolleys (malls and super markets). Most of these issues are now tackled with automated sliding doors. These double shutter doors work on photovoltaic sensors, lasers, or pressure devices, that also recognise the number of people, density, one way or two way passage (in-out) and nature of accompanying baggage. The controls occur with the actual width of opening and rate (speed) of opening.
A small sized drum, has two curved sliding shutters, which slide as overlap on the back-face to open a front slit, it gets closed while opening a slit on the back face.
Drums of revolving doors occupy a lot of floor space inside and outside of the entrance lobby. Small or barely adequate height drums are better in terms of leakage of air-noise, but the top surface (of the roof) is difficult to design or manage. The obvious solution to this is to make revolving doors, as high as the ceiling. ‘Tallest revolving door was reportedly about 16 feet high with 4 wings.’
Manual revolving doors rotate with manual push over the grab bar (horizontal handle bar). Automatic revolving doors have speed controls to retard the speed of rotation and stop position. Winged shutters, often have ‘book-fold’ like collapsing facility to open up dual sided passage, for heavy rush or disaster evacuation. Exit doors for fire and other emergencies must open out to a safer zone or an open area. Many bye laws require revolving doors to fold flat in the direction of egress.
The regional and cultural preferences determine the clock or anti clock-wise movement of the shutters. Revolving doors, typically, revolve counterclockwise, in right-hand drive countries, and by same logic, in left-hand drive countries, revolving doors should revolve clockwise, but not always.
Revolving Doors are ideal, where there are consistent, and comparatively heavier inward-outward traffic, as in high rise commercial buildings, malls and transport hubs. Hinged or sliding doors, attached to lobbies with elevators or escalators, are prone to chimney effect, sucking in air at high speed at the base and ejecting it through the vents, shafts and ducts.
Revolving doors are also function as security devices, capturing images of the entrants from many sides, restrict entry to a single person at a time and control the rate or number of entrants. It is difficult to ‘tailgate’ behind an authorized person. Revolving doors can be designed for one-way traffic. Glass shutters of revolving doors allow people to see and anticipate each other’s behaviour. In many precincts revolving door is required to be collapsible or flanked by at least one outward swinging hinged door of equivalent capacity, located near to it.
Turn Stiles (also called a turnpike, gate-line, baffle gate, automated gate, turn gate) These were used on farms and estates to disallow entry of animals. In a half cylinder of a small diameter, a hinged shutter of partial height or a rotatable bar is placed, making the path of entry skewed. Instead of the drum a small depth passage has up-down moving bar restricting the entry. These are used in subways, transport hubs, sports facilities, entertainment arenas to prevent unauthorized entrants. Full height turnstiles, mainly used to control rowdy spectators as in football or rugby stadiums are called ‘Rotogate’.
There are many other opening systems incorporating the revolving shutters. Butterfly doors are winged shutters in automobiles and Scissor doors are commonly called ‘Lambo doors’ because used by Lamborghini cars.
Mystically, an open door represents good fortune, a new opening in life or a desire to open up the feelings. A revolving door means a monotonous period ahead, and a trap door harbinger of shocking news. A locked door reflects missed opportunities, denial of opportunities or can represent the need to close the door over the past. A door opening outward may show that one needs to be more accessible to others, however, an inward opening door represents the desire for inner exploration and self-discovery. A house with one door is a preferred abode. Evil spirits enter the house from a back door. A front door is a normal entrance and a back door a nominal one.
Interior Design Assist 