interlaced alternating stairway
Two alternating stairways interwoven within one stairwell, with adjacent straight flights rising in opposite directions.
Interlaced alternating stairways are two alternating stairways interwoven with each other in a single stairwell or vertical space. Each flight rises straight from one floor to the next, while another one traverses an adjacent space in the opposite direction. The two stairways generally serve the same floors but take turns accessing points on either side. Each of the two stairways can be walled off from the other so that the person inside may be unaware of the other one.
This type is used sometimes in high-rise buildings as a means of concentrating maximum stairway access into a limited space. Its space efficiency is even greater than a hairpin stairway's because it does not require intermediate landings, and it allows better transportation of large objects because there are fewer turns. However it is generally practical only when there is a need for multiple stairs within a small space.
The routes can be separated by walls, but enclosure is optional. The interwoven straight flights define the arrangement; neither route needs to be visible from the other.
Related definitions
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alternating stairway
Straight stair flights that reverse direction at each floor level, allowing continuation without a long connecting walk. -
angled stairway
A generally L-shaped stairway with one turn of about 90 degrees between successive floors, using a landing or winders. -
angular helix stairway
A stairway following an angular polygonal path around a central core, shaft, open space, or atrium. -
curved stairway
A stairway following a curved path without completing a circle or helix, including stacked half-circular flights. -
fan stairway
A spreading stairway with angles or bends in individual steps, producing a fan-like or amphitheater-like arrangement. -
hairpin stairway
A stairway whose flights reverse direction by 180 degrees between floors, without a third direction of ascending steps. -
helix stairway
A stairway arranged around a central axis in a circular path, with or without a central post or open shaft. -
interlaced angular helix stairway
Two or more angular helical stairways interwoven within the same shaft or vertical space. -
interlaced helix stairway
Two or more helical stairways interwoven around the same axis within one shaft or vertical space. -
meandering stairway
Stairs which turn at or between levels but do not fold back in the same stairwell. -
progressive stairway
Multiple stair flights continuing along one straight route through successive levels without requiring a turn. -
simple stairway
One or more straight stair flights, with successive flights vertically aligned and reached by walking back at each floor. -
split stairway
Stairs whose pathway forks into clearly distinct directions on the way up or down. -
u-shaped stairway
A stairway with ascending flights in three directions and two turns between floors, forming a rectangular half-helix.