This paper describes an experimental study of workers’ responses to proximity warnings of static safety
hazards on construction sites using a location-based proximity warning system named the Proactive
Construction Management System (PCMS). A method of evaluating workers’ responses to proximity
warnings is proposed. The method consists of six variables: warning time and distance (the time and
the minimum distance to a hazard when a worker receives a warning), dangerous time and distance
(the time and the minimum distance to the hazard when the worker comes close to the hazard), and
response time and distance (the difference between dangerous time and warning time, and the difference
between dangerous distance and warning distance). Finally, whether a worker responds to a warning is
evaluated against a two-second threshold and a two-meter threshold in terms of response time and
distance respectively.
The experiment was conducted over 17 workdays with the participation of 72 workers and resulted in
5391 warnings on a real-life construction project in Shanghai, China. The workers’ responses were analyzed
with respect to two factors: building trades and a-priori risk levels. The research found that workers
responded to proximity warnings actively, but slightly differently across the selected building trades; carpenters
had longer response latency in hazardous areas than ironworkers did, and response percentages
were high for hazardous areas with high risks. The results also show evidence that PCMS has the potential
to improve workers’ safety performance. The limitations of the present study and future research directions
are also addressed.