alternating stairway
Straight stair flights that reverse direction at each floor level, allowing continuation without a long connecting walk.
An alternating stairway consists of straight flights of stairs which continue in the opposite direction at each floor level. This allows persons to climb multiple floors without walking a long distance between the top of one flight and the bottom of another. It is especially easy to construct, but requires more space than most other configurations. This is one of the most common stairway arrangements.
The reversal takes place at the floor level. A hairpin stairway instead turns back between successive floors.
The flights remain straight. The configuration describes their successive directions rather than the shape of individual steps.