Risk assessmentCanadian city developed mathematical formula to evaluate risk

The City of Hamilton, Ontario has ranked terrorism fourth on its list of top ten emergency risks. Terrorism ranks above flooding despite the fact that the city has never experienced a terrorist attack, yet flooding from major storms has cost the city millions in the past and has forced the city’s emergency plan to be initiated twice.

CBC reports that Hamilton’s emergency management office uses a mathematical equation to rate risks:

Risk = (Probability + Frequency) X (Sum of Consequences)

Consequences in the equation include fatality, injury, critical infrastructure damage, property damage, environmental impact, and social and economic impact.

Carla McCracken, Hamilton’s emergency management coordinator, agreed that while the city has never had a terrorist attack, the potential consequences defined by the equation are reasons for the terrorism risk ranking. 

Hazardous Materials and Explosions are ranked number one on the emergency risk list due to the frequency of occurrence. Past explosion or incidents related to hazardous materials include: a chemical fire in Stoney Creek in 1986; another chemical fire in Dundas in 1987, when 200 people had to be evacuated; the Lottridge St. recycling service fire which caused more than eighty homes to be evacuated; and a 25 August 2009 fire at Ancaster’s Archmill woodworking factory which took seventy firefighters and eighty trucks to put out.

“The frequency of it (explosions) happening again was a little bit higher than other ones and the probability of it happening again with our community profile was also large,” McCracken said.

Flooding is ranked fifth on the list, below Terrorism and Hazardous Materials and Explosions, because the city has experience dealing with the issue. McCracken describes the response to a 2009 flooding incident in which twenty-six city facilities flooded. “We had first responders going in, helping people out of their homes, going into basements shutting off utilities. Public Works was blocking off roads.”

Hamilton’s Emergency Management Act has been activated ten times since the act’s enactment ten years ago. When the act is initiated, emergency staff related to the emergency hold response meetings with all appropriate city staff, including the mayor. Employees within the emergency team operate from the city’s emergency management center to manage the staff on the ground and to make sure city services are functioning in areas outside the emergency zone.

The provincial government provided Hamilton with a list of potential risks and required city officials, part of a committee that included representatives from police, fire services, school boards, and community leaders, to select the emergency risks most likely to occur. “We then selected our model for analysis which basically gave us our formula,” McCracken said. “Based on research we had done and the people around the table, that gave us our numbers…. it is very qualitative in nature and influenced by the people around the table.”

McCracken notes that the emergency risk list is subject to revision every five years and may look different two years from now.

Top 10 risks, in order, for Hamilton, Ontario:

1. Hazardous Materials and Explosions
2. Energy Supply Emergencies
3. Epidemics/Pandemics
4. Terrorism
5. Flooding
6. Structure Fire (major)
7. Tornadoes (windstorm and microburst)
8. Transportation Accident - Motor Vehicle
9. Ice Storms
10. Earthquake