Quantified Risk Scale

The Quantified Risk Scale uses three variables and applies more precise qualitative criteria as well as specific values to calculate individual risk scores. The three risk variables are:

  • frequency of exposure,
  • probability a crash or other loss will occur, and
  • severity of impacts.

Table Three shows the scoring criteria used to rate each of the variables associated with a given hazard.

Table Three:  Quantified Risk Scoring Guide
Rating Frequency of Exposure Probability of Occurrence Severity of Consequences
10 Continuous - occurs many times per day. It is almost certain that an incident will occur and cause the expected results; likelihood greater than 50% Results in 2 or more fatalities, catastrophic property damage (more than $1 million) and/or business termination
8 Frequent - occurs several times each week, or daily It's quite possible or probable the incident will occur; likelihood 10% to 50% Results in single fatality, severe property damage (greater than $500,000) and/or lengthy business interruptions
6 Common - occurs about once each month It's a possible occurrence, but it is unusual; 1% to 10% likelihood Results in serious injury, loss of use of limb or long-term disability, property damage $100,000 to $500,000 and/or business interruptions up to one month
4 Occasional - occurs 3 - 5 times each year It hasn't happened in this organization, but it is remotely possible; likelihood less than 1% Results in injuries and short-term disability, property damage less than $100,000 and/or minor business delays
2 Unusual - occurs once a year It's conceivable but very unlikely; not aware this has ever occurred, but it could; likelihood = 1 in 10,000. Results in injuries requiring medical aid and incurring lost time, property damage less than $25,000 and/or minimal business inconvenience
1 Rare - possible, could occur once every 10 years It's practically impossible; likelihood = 1 in 100,000 Results in negligible impacts to well-being of any person (employee or external), little or no property damage and no impacts on business processes

 

Applying the Quantified Risk Scale Approach

To help you use the Quantified Risk Scale (QRS) approach, we developed a QRS assessment tool. It has three (3) components: a road hazard inventory, the scoring criteria (the Quantified Risk Scoring Guide above), and the QRS Assessment Tool. The outputs of this method are individual risk scores that enable you to easily identify the hazards that deserve top priority.

Before seeing how the QRS is applied, it is helpful to re-visit the risk variables, and to keep the following questions in mind.

  • Frequency of exposure – How many and how often are drivers exposed to this hazard? Does frequency of exposure vary widely among drivers? If it does, you will need to group drivers by level of exposure and calculate a relative risk for each driver group.
  • Probability of occurrence – If your drivers encounter a given hazard, how likely is it an incident will occur? Do you notice that some employees with different types of driving assignments have a greater or lesser probability of being involved in a crash that involves a given hazard?
  • Severity of consequences– If an MVI incident occurs, what do you expect the impact will be? Will someone likely be injured? How severe will the injuries be? How much will it cost to repair or replace damaged property? How will it affect your business?

The ABC Trucking Ltd scenario applies the above scoring guide. Using a few of the hazards that ABC Trucking regional delivery drivers face, below is an explanation of why ABC Trucking scores risks the way they do.

Table Three:  Quantified Risk Scoring Guide
Hazard / Contributing Factor Frequency of Exposure Probability of Occurrence Severity of Consequences Risk Score
distraction - texting or talking on cell phone while driving 6 6 4 144
distraction - conversation with or interference by passenger 1 2 6 12
distraction - responding to dispatcher call, 2-way radio 8 8 4 256
insufficient orientation or training, lacks necessary competencies; inexperienced 2 8 6 96
does not recognize driving hazards or hazardous conditions and/or adapt driving accordingly 6 8 6 288

 

Cell phone distraction – ABC issues each regional delivery driver a company cell phone for emergencies. ABC has strict procedures prohibiting phone use while driving, but phone records show that each month at least one of their drivers is on their phone while driving (frequency = 6). Although ABC has not yet experienced a crash due to cell phone distractions, they know other trucking companies have; it is quite possible ABC will experience such a crash if cell phone use continues (probability = 6). They also know that when those crashes occur, they typically result in lost time injuries to the driver and repair costs up to $100,000 (severity = 4).

Passenger distraction – ABC has a clear policy against drivers carrying non-employee passengers (exposure = 1). Even if a driver disobeys the policy and carries a passenger, ABC feels it would be very unlikely to cause an incident (probability = 2). If a crash does occur, the expected consequences would be injuries and lost time plus property damage up to $100,000. However, because ABC would also be liable for health care costs of the passenger, the safety committee increases the severity rating one position (from 4 to 6).

Dispatcher distraction – ABC dispatchers have a reputation of demanding that drivers respond to calls immediately. Several times each day, a driver is distracted from their driving duties by a dispatcher’s call (exposure = 8). ABC drivers have reported 17 near misses (probability = 8) and one incident that resulted in lost time injuries and substantial repair costs (severity = 4).

Insufficient orientation – Most ABC regional delivery drivers are experienced veterans, but ABC has hired five new drivers in the last year to replace retiring drivers. Although they pair each new hire with a reliable mentor, ABC expects that new hires will sometimes encounter situations they don’t know how to handle when their mentor is not available for guidance (exposure = 2). One such crash (probability = 8) resulted in serious injuries to another motorist (severity = 6).

Hazard recognition – About once a month (exposure = 6), an ABC driver reports a near miss or is involved in a MVI that is  a consequence of the driver either failing to recognize a hazardous condition, or recognizing the hazardous condition but failing to adjust their driving to accommodate the condition. ABC has found that when that occurs, an incident is quite probable (probability = 8) and the consequences are costly (severity = 6).

Making Improvements and Reducing Risks

In their 2014 risk assessment, ABC recognized that their greatest risks came from drivers not recognizing hazards and hazardous conditions, or failing to adjust their driving accordingly (as per below).

Hazard Frequency Probability Severity Risk Score

Does not recognize driving hazards or hazardous conditions and/or adapt driving accordingly

6 8 6 288

 

Realizing it is not possible to eliminate those hazardous conditions, ABC enrolled drivers in training that explained how to actively look for and recognize hazards and showed them how to adjust their driving in anticipation of potentially hazardous conditions. In a recent risk review, ABC noticed that the frequency of near misses has declined, and drivers say they are less likely to be involved in a near miss or collision when they apply those techniques. The new risk assessment reflects the success of ABC’s risk management actions.

Hazard Frequency Probability Severity Risk Score
Does not recognize driving hazards or hazardous conditions and/or adapt driving accordingly 4 6 6 144

 

Advantages and Limitations of the Quantified Risk Scale

Advantages

  • deals with frequency of exposure as a distinct variable. Users assign a frequency score based on their knowledge of how many and how often drivers are exposed to each hazard. This step provides more concise risk scores, and lets the user set priorities with greater confidence.
  • scoring descriptors are more precise and require less “guess work” or interpretation than the Simple Risk Matrix.
  • resulting risk scores provide better differentiation between competing hazards, making it is easier to see which ones are the highest priorities.

Limitations

  • three rather than two variables to consider
  • greater reliance on records, data and statistics; a plus if you can access those numbers, but a minus if you can’t.

Rating the Risks and Applying Results

Because your risk scores set priorities for the real work of eliminating those hazards and managing risks, spend enough time on the risk assessment to get it right. The objective is to arrive at a well-reasoned relative ranking that will guide your safety efforts to deliver the “best bang for your safety bucks”.

For either model above, there are at least a couple of approaches to scoring the variables.

  • Work as a team to discuss each hazard and variable and consensually agree upon each ranking or score.
  • Have two (or more) knowledgeable individuals complete the rating independently and compare results. It’s unlikely that both would have identical scores, but overall results should be similar. If two assessors come up with quite different scores, each apparently perceives the exposure, probability or severity quite differently. They should look closely at why there is a difference, and determine what the best answer is.

Either way, when drivers look at the resulting ranking, they should agree that addressing those highest-ranked risks makes good sense. Managers should be able to see that investing in controls to address top-ranked risks should yield the greatest safety improvements and the best return on investment.

Taking Action

The key to making hazard identification and risk assessments work for you is to take action. Once you have decided on priorities, the next step is to develop measures to control those hazards and minimize associated risks. To learn more about developing those controls and building safe work procedures look to the next section in this Tool Kit.

To download the working tool, access: Quantified Risk Scale Assessment Tool (excel)

For assistance using the Quantified Risk Scale Assessment Tool, view the Using the Quantified Risk Scale Video Tutorial

For a more extensive example of how to apply the Quantified Risk Scale, download: Applying the Quantified Risk Scale - ABC Trucking Ltd (pdf)



Tool Kits