Question 6: Risk Assessment (Fine's Method) (10 marks)
Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.
What the attachment actually prints. The Page 5 chart is a
Fine risk-score nomograph with descriptive axes only — no numerals appear on the Likelihood, Exposure or Consequence scales. Each axis carries labelled tick points, and the answer is obtained
graphically: a line from the chosen Likelihood point through the chosen Exposure point to the
TIE LINE, then a second line from that tie point through the chosen Consequence point, read where it crosses the
RISK SCORE axis. Only the risk-score axis is numbered (8, 10, 20, 40, 60, 80, 100, 200, 300, 400, 500, logarithmic) and it is divided into five action bands, printed as:
- > 400 — VERY HIGH RISK: consider discontinuing operation
- 200 – 400 — HIGH RISK: immediate correction required
- 70 – 200 — SUBSTANTIAL RISK: correction required
- 20 – 70 — POSSIBLE RISK: attention indicated (printed "POSSILBE" on the paper)
- < 20 — RISK PERHAPS ACCEPTABLE
The axis descriptors are, top to bottom —
Likelihood: might well be expected at some time / quite possibly could happen / unusual, but possible / remotely possible / conceivable but very unlikely / practically impossible.
Exposure: very rare (yearly or less) / rare (a few per year) / unusual (once per month) / occasional (once per week) / frequent (daily) / continuous.
Possible consequences: catastrophe (many fatalities, >
$10,000,000 damage) / disaster (multiple fatalities, >
$1,000,000) / very serious (fatality, >
$100,000) / serious (serious injury, >
$10,000) / important (disability, >
$1,000) / noticeable (minor first aid case, >
$100).
Method. The nomograph is the graphical form of Fine's relation $\text{Risk Score} = \text{Likelihood}\times\text{Exposure}\times\text{Consequence}$. Because the chart itself prints no numerals on those three axes, the scale values used below are the standard Fine–Kinney ones (W. T. Fine, "Mathematical Evaluations for Controlling Hazards", 1971), which are the values the chart's own tick spacing reproduces. The chart, not the table, is the authority the question points to: every score below is read off the chart by the construction the sheet's own example demonstrates, and the tabulated arithmetic is given alongside as a check on that read (see the cross-check). The choice of descriptor on each axis is a matter of judgement; assumptions are stated, as the paper's Note 9 permits, and reasonable alternatives are acceptable if justified.
Fine's values for the descriptors printed on this chart:
| Likelihood | | Exposure | | Consequence | |
|---|
| might well be expected | 10 | continuous | 10 | catastrophe | 100 |
| quite possibly could happen | 6 | frequent (daily) | 6 | disaster | 40 |
| unusual, but possible | 3 | occasional (weekly) | 3 | very serious | 15 |
| remotely possible | 1 | unusual (monthly) | 2 | serious | 7 |
| conceivable but very unlikely | 0.5 | rare (a few per year) | 1 | important | 3 |
| practically impossible | 0.1 | very rare (yearly or less) | 0.5 | noticeable | 1 |
(a) Risk-Score Evaluation
Daily car commute (20 km each weekday, single-lane highway, 80 km/h). Likelihood that a given trip ends in a crash = remotely possible (1); Exposure = frequent — daily (6); Consequence of a crash at 80 km/h on an undivided highway, taken as a serious injury = serious (7).
$$\text{Risk}_{\text{car}} = 1 \times 6 \times 7 = \boxed{42} \;\Rightarrow\; \text{POSSIBLE RISK — attention indicated}$$
Weekly skydive (one jump every Sunday, single-engine aircraft). Likelihood that a given jump goes wrong = unusual, but possible (3); Exposure = occasional — once per week (3); Consequence of a failed jump = very serious (a fatality) (15).
$$\text{Risk}_{\text{sky}} = 3 \times 3 \times 15 = \boxed{135} \;\Rightarrow\; \text{SUBSTANTIAL RISK — correction required}$$
Lines to draw on the returned chart. For the commute: join remotely possible on the Likelihood axis to frequent (daily) on the Exposure axis and extend to the tie line; from that tie point draw through serious on the Consequence axis and read the risk-score axis where the line crosses it — just above the 40 mark, about 42, inside the 20–70 band. For the skydive: join unusual, but possible to occasional (once per week), extend to the tie line, then draw through very serious and read between the 100 and 200 marks, about 135–150, inside the 70–200 band. Both graphical reads agree with the arithmetic above, which is the point of drawing them: the chart is the instrument, and the multiplication is the check.
Cross-check on the scale values. The sheet already carries one worked example, drawn from conceivable but very unlikely (0.5) through occasional — once per week (3), then through very serious (15); its arrowhead lands between the 20 and 40 marks, i.e. in the 20–70 possible risk band, and the tabulated product $0.5\times3\times15 = 22.5$ sits in the same band. The example alone cannot separate one candidate consequence scale from another (it is a single point, read to about a tick's width), so the scale is settled the other way round — by the spacing of the labelled points on the three unnumbered axes, measured against the one axis the sheet does number. Stepping down the Consequence axis, the printed points are spaced at a near-constant ratio of roughly 2.5 from catastrophe to noticeable, which reproduces the Fine–Kinney series 100 / 40 / 15 / 7 / 3 / 1 and not the alternative 100 / 50 / 25 / 15 / 5 / 1 that some texts print — the latter would place serious and important roughly twice as high up the axis as the sheet draws them. The Likelihood and Exposure axes are spaced consistently with Fine's 10 / 6 / 3 / 1 / 0.5 / 0.1 and 10 / 6 / 3 / 2 / 1 / 0.5. Reading the two activity lines straight off the chart confirms the choice: the commute crosses just above 40 and the skydive between 100 and 200, whereas the 100 / 50 / 25 series would have demanded 90 and 225 — one action band higher in each case.
The contrast is instructive: the commute has high exposure but a lower consequence, the skydive lower exposure but a fatal consequence. The severe consequence makes skydiving the higher-scoring risk by a factor of about three, even though it is done once a week and the commute five times a week. Note the sensitivity of the commute figure, and state the assumption when answering: classing a highway crash at 80 km/h as very serious (a fatality, 15) rather than serious (7) gives $1\times6\times15 = 90$, which crosses the 70 boundary into substantial risk — correction required. The commute therefore sits close to a band boundary and its classification does depend on that judgement; the skydive, at 135, is comfortably inside its band. This is why the paper asks for the lines to be drawn and returned — the marker can see which descriptors were chosen.
(b) Reducing Each Risk
- Car commute — reduce likelihood/consequence: defensive driving, obey the speed limit, avoid distraction and fatigue, wear the seatbelt, maintain brakes/tires, use winter tires, choose a safer (divided) route; reduce exposure by carpooling less often, working from home some days, or relocating closer.
- Skydiving — reduce likelihood: proper training and certification, jump only in good weather, meticulous equipment inspection and packing, and carry a reserve parachute with an automatic activation device (AAD) and altimeter; reduce exposure by jumping less frequently; reduce consequence is largely fixed, so control focuses on reliability and redundancy.
(c) Human Error versus Equipment Failure
- Car commute — predominantly human error: the large majority of road crashes stem from driver behaviour (speed, distraction, fatigue, misjudgement), though equipment failure (brake/tire failure) contributes a minority.
- Skydiving — both, but with a strong equipment-failure consequence: a parachute malfunction is catastrophic, so equipment integrity is critical; however, with modern gear, a reserve and an AAD, statistics show human error (poor canopy control, late deployment, bad landing decisions) is actually the leading cause of skydiving fatalities. The distinction to draw: driving is human-error dominated, while skydiving is the activity where an equipment failure is most likely to be immediately fatal—hence its emphasis on redundancy and inspection.
