STAIRWAY UNIFORMITY MEASUREMENT: WHAT LATERAL LOCATION SHOULD BE MEASURED

An experimental study sought to extend understanding of the nosing-to-nosing method for measuring dimensions of steps in a stairway. A human factors expert retained to assist an attorney in a case of injury or death from a stairway fall needs to decide the lateral location for taking the measurements. This experiment was undertaken to provide experts with a justifiable basis for choosing the location. Using a campus stairway and 16 student subjects, a randomized complete block experiment compared their lateral location while performing four tasks—ascending with or without the handrail, and descending with or without the handrail. Results showed task significantly affected lateral distance. Based on findings from this experiment, and some professional judgment, the authors provide recommended ranges for the lateral locations for measuring step dimensions—30 to 38.5 cm for ascending, and 19 to 28 cm for descending

Stairway Uniformity Measurement: What Lateral Location Should Be Measured?

BACKGROUND: This project addressed an unresolved issue involving measurement methods for determining step uniformity. Leading experts on stairway safety agree that lack of step uniformity within a flight contributes to risk of missteps. A relatively new method for precisely measuring step dimensions is the nosing-to-nosing method. An issue in applying the method is lack of agreement on the lateral location to make the measurements. That location depends on where stairway users ascend and descend relative to the width of the steps. A prior investigator examined people descending to determine the lateral distance between the handrail center and the mid-line of the person’s body. He found the median was 44 cm. AIM: The two objectives of the experiment were to: (1) determine if a different set of stairway users will have the same median lateral distance from the handrail as those described in the prior observational study, and (2) determine if the lateral distance of participants is affected by their direction of travel and use of a handrail. METHODS: The investigators established visible distance markers on one stairway in a campus building and videotaped volunteer students ascending and descending the flight of stairs. Each of the 16 participant ascended with and without using the handrail, and each descended with and without using the handrail. Images were printed and analyzed to determine their lateral distance between the inner edge of the handrail and a point midway between the participant’s knees. Results were analyzed statistically to test hypotheses corresponding to the two objectives. RESULTS: The previous study found a median lateral distance of 44 cm when measured from the center of the handrail. Using comparable data, the median found in this study was 25 cm. Results of this study indicated that lateral distance from the handrail is significantly affected by the direction of travel and by use of the handrail. The greatest lateral distance was for ascending with the handrail. The shortest lateral distance was for descending without the handrail. VALUE: Committees develop and periodically revise standards for stairways leading to fire exits and workplace facilities. The practical value of this project is providing empirical evidence that standard developing committees may consider when convening to update their requirements and guidelines on how to measure step uniformity