Contents lists available at ScienceDirect Safety Science journal homepage: www.elsevier.com/locate/safety The effects of glass stairways on stair users: An observational study of stairway safety Karen Kim ⁎ , Edward Steinfeld Center for Inclusive Design and Environmental Access, University at Buffalo, The State University of New York, Buffalo, NY, USA ARTICLEINFO Keywords: Stair safety Stairway design User behavior Gaze behavior ABSTRACT The purpose of this study was to assess the safety of a winding glass stairway by observing the behavior of stair users and to identify issues that should be studied in a laboratory setting. A checklist for coding stair use be- haviors was developed. Video observations were conducted in a retail store with a glass stairway (GS) and a shopping mall with a conventional stairway (CS). Key behaviors related to safety (tread gaze, diverted gaze, handrail use) and stair incidents on the two stairways (GS and CS) were identified from the recordings and compared. On the glass stairway, more users glanced down at the treads (GS: 87% vs. CS: 59%); fewer users diverted their gaze away from the stairs (GS: 54% vs. CS: 67%); and handrail use was higher (GS: 32% vs. CS: 24%). Incident rates were much higher on the glass stairway (6.2%) compared to the conventional stairway (0.7%). Walking on winding treads made of glass may be more dangerous than walking on conventional ma- terials due to reduced visibility of the tread edge or reduced friction between shoes and treads. Recent laboratory research suggests that stairway users may behave more cautiously using stairways with glass treads but the results from this study demonstrate that the benefit of increased caution can be negated in real world conditions. 1. Introduction Stairway falls are clearly a public health concern. Each year in the U.S., about 1,300,000 hospitalizations and 2,100 deaths are caused by stair-related injuries (National Safety Council, 2015). The annual cost of stair-related injuries is the largest contributor to product injury costs ($92 billion dollars), followed by injuries due to floors and home fur- nishings (Lawrence et al., 2015). While the majority (90%) of falls occur in home settings (Pauls, 2013), the fall risk is equally problematic in public buildings where it represents a major source of injury claims, e.g., in workplace, retail, and leisure environments (Cohen, et al, 2009; Templer and Archea, 1983; Templer, 1992). Danford et al. (2009) found that using stairways was the most problematic activity reported by respondents in an online survey. Stairway use is also a cross-dis- ability issue since it involves mobility, perception, and cognition (Archea et al., 1979; Templer, 1992). Thus, creating usable and safe stairways should be a top priority for the building industry. Knowledge for the appropriate design of stairways is limited, however, which has resulted in difficulty developing best practices and improving design guidelines and building codes. In the absence of definitive knowledge, contemporary architects are experimenting with unusual stairway de- signs, including the use of glass treads, which may increase a person’s risk of tripping, slipping, or balance problems. In a study on trends in stairway design practices, a high proportion of unsafe stairway designs were constructed, in contradiction to best practices and even in clear violation of building codes and standards (Kim and Steinfeld, 2016). This study is part of a larger investigation of stairway safety, which includes a literature scan of design practices (Kim and Steinfeld, 2016), additional observational studies (Kim and Steinfeld, 2014) and la- boratory research (Boyaninska, 2018; Novak et al., 2016). A winding stairway in a popular retail store was selected for the study because it has unusual design conditions that may increase the risk of falls; these include a winding stair configuration, open risers, and glass treads. Winding or spiral stairways are considered to be more dangerous than straight stairways because the treads are tapered so that users must twist their bodies and shift their weight differently on the left and right foot while climbing the stairway (Steinfeld and Maisel, 2012). The risk of losing balance is higher compared with straight treads which do not require users to rotate their center of gravity while traversing the stairway (Archea et al., 1979). In addition, people tend to stay to the right on stairways in the U.S., therefore the effective tread depth is different going up than down on winder treads. When stairs curve up- ward in the clockwise direction, people tend to climb up the steps along the inner radius where the tread is narrower and descend along the https://doi.org/10.1016/j.ssci.2018.11.010 Received 20 October 2017; Received in revised form 13 October 2018; Accepted 11 November 2018 ⁎ Corresponding author at: Center for Inclusive Design and Environmental Access, University at Buffalo, School of Architecture and Planning, 3435 Main Street, Hayes Hall, Buffalo, NY 14214-8030, USA. E-mail address: karenkimsun@gmail.com (K. Kim). Safety Science 113 (2019) 30–36 0925-7535/ © 2018 Elsevier Ltd. All rights reserved. T