Understanding safety risk through fault tree analysis


In 2018, Technical Safety BC held a number of workshops aimed at gaining a deeper understanding of high risk events which take place. We engaged industry representatives as subject matter experts to look closely at the following:

  • ammonia releases;
  • carbon monoxide exposure;
  • electric shock; and
  • escalator brake failures, entrapments and pile-ups. 

To complete this analysis, we used fault tree methodology to identify the conditions required for a high risk event to occur and all the possible causal factors leading up to that occurrence. Fault tree analysis uses a top-down, deductive failure analysis in which an undesired state of a system is analyzed using Boolean logic to combine a series of lower-level events.

The Fault Tree reports, also shown below, provide a number of recommendations to address causal factors. Technical Safety BC will be using this information to help inform decision making around risk, and will focus on those which we believe will have the greatest impact on safety. 

"Our goal is to improve the overall safety performance within targeted industry sectors and, over time reduce the number and impact of high risk events," explains Alina Urloiu, Programs Manager, Safety Oversight. "By using fault trees to help us understand what activities lead to certain events, we are better able to target our efforts to enhance safety.

View the fault trees and their respective studies below:

Boiler, Pressure Vessels and Refrigeration

Ammonia Release Fault Tree Study
Ammonia Release Fault Tree


Electric Shock Fault Tree Study
Electric Shock Fault Tree


Carbon Monoxide Fault Tree Study
Carbon Monoxide Exposure Fault Tree

Elevating Devices

Escalator Fault Tree Study
Escalator Brake Failure Fault Tree
Escalator Pile Up Fault Tree
Escalator Entrapment Fault Tree

These fault trees will be used by Technical Safety BC to enhance our Accident Prevention Model which we use to prioritize assessment, education and outreach, enforcement, and research activities. By using research to enhance our decision making, we can better protect the public harm and work towards our goal of achieving Safe technical systems. Everywhere. 

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