Original publication: 2016 | Peer-reviewed journal article
Source authors: M. Eyre, P. J. Foster, K. Hallas and R. Shaw
Date note: The journal issue is dated 2016; the supplied manuscript copy carries a 2015 date.
About this research
Stair accidents can cause serious injuries and fatalities, particularly during descent. The design and condition of the staircase may contribute, even where an initial inspection has identified no obvious broken or loose components.
Accurate measurements of step rise, going, tread and nosing geometry can be essential to establishing whether stair design or deterioration contributed to an accident.
This collaborative study evaluated whether three-dimensional laser scanning could complement traditional on-site measurement methods during the investigation of fatal stair falls.
How the research was conducted
The researchers compared conventional measurements using an inclinometer, rule and tape measure with 3D laser scanning at two fatal-accident locations: a set of quayside steps involved in a fall into a river, and worn stairs leading to a public house beer cellar.
The laser-scanning method produced point-cloud representations of each environment. These could be aligned to a coordinate system following the staircase, sectioned at different locations, measured and used to generate visual reconstructions.
The investigation considered step rises and goings, stair pitch, handrails, the location of the nosing, the effect of wear and the measurement uncertainties associated with both methods.
Key findings
Laser scanning captured a detailed three-dimensional record of each location.
The datasets enabled the investigators to return to the measurements, inspect different sections of the stair, visualise handrails and assess the wider accident environment without relying only on a set of isolated dimensions.
Agreement with conventional measurements depended on the case and measurement location.
For the quayside steps, dimensional differences between techniques reached approximately 5 mm. For the worn cellar staircase, some measurements at the centre showed differences of up to 10 mm in rise and 13 mm in going; comparisons at other locations produced discrepancies as large as 24 mm.
Wear is an important aspect of stairway geometry.
The cellar staircase had pronounced wear in the centre. By examining different digital sections, the researchers could compare the worn contact region with the sides of the stairs and estimate aspects of the original nosing geometry.
A digital model can improve communication of complex hazards.
Three-dimensional representations help explain stair layout, irregularity and accident context to people who were not present at the site. They can also provide a permanent record for later inspection, reconstruction and education.
Interpreting the findings
The study demonstrated considerable benefits from laser scanning, but did not establish that scanning was always more precise than carefully performed conventional measurement. It identified error sources including registration, resolution, coordinate alignment and subjective interpretation of point-cloud locations.
When dimensional tolerances are narrow, the reliability and uncertainty of the method are critical. The authors regarded laser scanning and conventional surveying as complementary tools rather than treating one as universally superior.
The study investigated stair geometry, not the coefficient of friction at stair nosings.
Why it matters
The research establishes a practical principle for stair safety: measurements must be accurate enough for the safety question being asked, and their limitations must be understood. It is also a direct example of evaluating a new measurement technology using real accident investigations.
This historical work is relevant background for future methods intended to assess other stair-safety properties, including slip resistance at a nosing, without implying that those later tests were part of the original study.
Original research
Eyre, M., Foster, P. J., Hallas, K. and Shaw, R. The use of laser scanning as a method for measuring stairways following an accident. Survey Review, 48(347), 121–129 (2016). DOI: 10.1179/1752270615Y.0000000014.