Simple Risk Matrix

The simple risk matrix in Table One relies on probability and severity scores of high, medium or low to assign relative risk rankings. The color-coding in the matrix provides you with a visual sense of the relative priority attached to that hazard.

Table Two provides comparative criteria or descriptors to help determine the probability and severity associated with each hazard. The outputs of Table Two are the inputs for Table One.

Table One:  Simple Risk Matrix
Severity HIGH


Table Two:  Simple Risk Matrix Assessment Descriptors
Rating Probability Severity
  • Frequent or repeated event
  • Occurs at least once a year in the organization
  • Occurs several times during a project
  • Occurs often in similar circumstances (e.g. in another company that does work similar to yours)
  • Greater than 50% chance of occurring
  • Serious or disabling personal injury, permanent disability or fatality
  • Costs to repair / replace property damage greater than $100,000
  • Loss of business function for extended period, substantial consequences for business
  • Event is known to occur, but not frequently
  • Occurs less than once a year in organization
  • Has occurred in similar circumstances (e.g. in another company that does work similar to yours )
  • 10% to 50% chance of occurring
  • Injury requiring medical aid with or without lost time from work
  • Costs to repair / replace property damage $25,000 - $100,000
  • Loss of business function for short period, modest consequences for business
  • Unlikely event, has not occurred in your company but could happen
  • May happen once in 10 years
  • Has never been observed, but possible
  • Less than 10% chance of occurring
  • No injury or minor injury requiring first aid
  • Costs to repair / replace property damage less than $25,000
  • Minor business interruption

Using the Simple Risk Matrix

Adapt Risk Assessment Criteria to Your Organization

Table Two (above) provides several descriptors with reasonable thresholds designed to yield appropriate probability and severity ratings for driving-related hazards in many workplace circumstances. However, you should review each descriptor, consider your company’s business processes, values and risk tolerances, and revise the descriptors to fit your needs.

For example, for some larger employers, property damage costs of $25,000 have small impacts to their bottom line, and such a loss is properly scored as having low severity. For other organizations, $25,000 property damage costs can have a significant impact on their viability, and would therefore have medium or high severity. For some businesses, (such as self-employed contractors), even a short-term business interruption can have disastrous consequences, so would be scored as having high severity.

You may want to add environmental impacts (e.g., fuel spill, toxic release) or other consequences that could be associated with a crash, and are important for your organization.

Assign Scores for Probability and Severity

Once you have made those adjustments to the descriptors, the next step is to assign a probability score and a severity score to each of the hazards you want to assess (e.g. from the Road Hazard Inventory).

When scoring each hazard, keep the following questions in mind.

Probability – Collectively, how often are our employees exposed to this hazard? In our organization, or in other organizations like ours, how often does this occur? How likely is this to occur?

Severity – If this hazard causes a crash or other incident, what are the most likely outcomes? How much will it cost? How severe are the injuries and other losses likely to be? How will that impact our business?

Applying the Simple Risk Matrix

  • Example One - A & R Taxi Ltd

    Below is a snapshot of how A & R Taxi Ltd used a simple risk matrix to prioritize their action plans.

    Example One: A & R Taxi Ltd
    Hazard Probability Severity Priority
    Taxi won’t start due to mechanical (battery) failure High – happens at least once each year across fleet Low – minor business delay; cost of repair = $100 Medium
    Taxi collides with another vehicle at intersection High – happens at least once per year across fleet Medium – lost time due to injuries; cost to repair damaged property = $45,000 High
    Taxi backs into pedestrian while parking Medium – happened once before to this company; a few occurrences at other taxi companies High – pedestrian receives serious injuries; liability costs greater than $100,000 High
  • Example Two - ABC Health Services

    In the last two years, ABC Health Services has experienced two near crashes because their driver is distracted by a passenger or client. Based on what “just about” happened, ABC thinks such a crash would probably result in injuries to the driver and client (and perhaps an occupant of another vehicle) and it would cost about $50,000 to repair damaged vehicles. The ABC health and safety committee assign a medium severity and high probability to such outcomes, and ranks the priority of managing risks associated with passengers distracting their drivers as HIGH.
  • Example Three - XYZ Courier Services

    XYZ Courier Services is working hard to win contracts. Recently, some drivers have adopted the practice of eating lunch “on the road” thinking it will improve productivity. Others are concerned this added task reduces their ability to pay attention to traffic, and drive. Yesterday, a driver damaged his van when he backed into a loading dock while trying to eat a sandwich. Today, XYZ has hired a contractor to fix their client’s loading dock, and is trying to repair its damaged business reputation and keep that client. XYZ management assigned a high severity and high probability to such outcomes. They have made eliminating “driving lunches” a HIGH priority.
  • Example Four - QST Construction

    QST Construction is expanding its resource road construction business to highway projects. They are proactive about safety issues, but don’t have experience to know how severe or probable MVIs will be in their new highway work. They can’t afford a new fleet of pickups, so will have to rely on their “old” fleet. QST is hiring new drivers for the projects. Management is unsure whether they should first pay attention to vehicle inspection and maintenance procedures, or improve their driver orientation process.

    QST estimates potential consequences of a crash due to either a mechanical failure or deficient driver orientation are about the same - lost time injuries and repair costs less than $100,000. Over the last 15 years, QST has had two vehicle mishaps due to mechanical failure; they estimate the likelihood of vehicle failure incidents as medium. However, because QST employees and supervisors have very little highway construction experience, QST feels the likelihood of a driver-related mishap is greater than the likelihood of a vehicle-related mishap. They have started building a better driver orientation process.

To download the working tool, access: Simple Risk Matrix Assessment Tool (excel)

For assistance using the Simple Risk Matrix Assessment Tool, view the Simple Risk Matrix Assessment Video Tutorial

For a more extensive example of how to apply the Simple Risk Matrix, download: Applying the Simple Risk Matrix - Top Notch Consultants (pdf)

Advantages and Limitations of the Simple Risk Matrix

This section briefly describes some of the advantages and disadvantages of using a simple risk matrix. Reviewing these will help you appreciate some of its strengths and limitations, and see where its use best fits your organization.


  • Intuitive – uses the assessor’s perception of organizational driving risks
  • Can get reasonable risk rankings without extensive data or numbers
  • Adaptive – can adjust risk criteria to match company circumstances
  • Two rather than three variables to consider

One advantage of the simple matrix is that it is not necessary to have precise information or data about each hazard. Instead, it enables you to do a comparative analysis that, in some applications, can be sufficient. For example, you might not know how often a given hazard has contributed to crashes in the last five years. You might not have accurate reports on the severity of their consequences. As long as you have an informed sense that hazard A is more likely than hazard B to contribute to a crash, you can assign a greater probability to hazard A. If you know that MVIs that involve hazard A almost always have more severe consequences than MVIs involving hazard B, you can assign a comparatively greater severity ranking to hazard A. Applying those non-precise, qualitative inputs to the risk matrix enables you to assign priorities and start on your action plan.


  • Results are relative and therefore less precise then quantitative methods.
  • When there are several risks to evaluate, all output rankings will fall into three rankings – low, medium and high. Certainly, hazards that get a “high” score are the first priority. However, if there are a dozen of more hazards that receive a “high” ranking, it is not obvious which three are your top priorities.
  • To get reliable rankings from a simple matrix, assessors need a good sense of the frequency with which drivers are exposed to each hazard and the associated probable severity. That experience and knowledge can be difficult to come by.


Tool Kits