Why does speed matter so much?

Braking distance scales with speed squared — doubling speed quadruples stopping distance. From 50 to 100 km/h, total stopping distance (thinking + braking) on dry asphalt grows from ~28 m to ~84 m. This is why speed limits in built-up areas are so much lower.

How wet does the road need to be to derate?

Visibly damp surface starts to derate friction. Heavy rain (standing water) drops coefficient from ~0.7 (dry) to ~0.4. Aquaplaning above ~80 km/h on poorly-drained surfaces effectively zeroes the friction.

Is the 2-second rule the same as stopping distance?

No — the 2-second rule is the gap between vehicles to give yourself reaction time before the car ahead's brake lights register and you can react. Total stopping distance is reaction + braking. Tool #24 covers the spacing rule specifically.

What factors drive JRA score?

Per IOGP 365: distance, time of day (night doubles risk), driver fatigue (hours on duty), vehicle condition, road type, weather. The tool weights each and returns a Low/Medium/High score with required controls.

When does a journey need a written JRA?

Most major oil & gas operators require written JRAs above ~50 km, on unfamiliar routes, at night, in adverse weather, or with cargo above a defined risk class. Local procedures override; default to written for High-scored journeys.

What's the maximum daily driving allowed?

IOGP recommends maximum 10 driving hours per duty day, with 30-minute breaks every 2 hours. Many client contracts tighten to 8 hours or limit night driving to genuine emergencies only.

What's the 2-second rule?

A simple field-applicable check: pick a fixed point (sign, tree); when the vehicle in front passes it, count 'one-thousand-and-one, one-thousand-and-two.' If you reach it before finishing the count, you're too close. In poor conditions, increase to 4 seconds.

How big should a convoy be?

Typically 3–5 vehicles maximum. Longer convoys lose visibility of lead/tail vehicles, increase the rear-end risk at junctions, and tend to fragment. Split into multiple convoys with separate radio call signs if needed.

What spacing on rough terrain?

Dust and gravel demand much larger gaps — typically 100 m minimum, more if dust obscures the road. Stay outside the dust cloud of the vehicle in front to keep your sight line clear.

Driving Safety – Stopping Distance, JRA

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14Stopping Distance Calculator

Stopping distance = thinking distance + braking distance. d_b = v² / (2·g·(μ + sin θ)) where μ is the friction coefficient for the surface and θ the slope. Heavy vehicles use a typical effective μ of about 75% of a light vehicle on the same surface.

Vehicle type

Speed (km/h)

2080 km/h160

Road surface

Gradient (%) — positive uphill, negative downhill

Reaction time (s) Trained driver: 1.0 s · Average: 1.5 s · Distracted/fatigued: 2.5 s+.

Load weight on heavy vehicle (kg, optional) i

Result

— m total

—

Thinking distance—

Braking distance—

Effective μ—

Equivalent to—

15Journey Risk Assessment

Generates a structured journey-risk score from route, time-of-day, weather and driver factors. Includes mitigations like rest stops, alternate route or postponement.

Route distance (km)

Highway %

Rural %

Urban %

Estimated driving hours

Number of planned rest stops

Time of day

Weather

Driver experience

Vehicle condition

Risk score

— / 100

—

Mitigations

24Convoy Spacing & 2-Second Rule

Compute the minimum following distance for the speed and conditions, total convoy length, and the radio call-time gap between vehicles. Adjust the time-gap rule (2 s dry, 3 s wet, 4 s heavy/tow) per IOGP Land Transport Safety guidance.

Speed (km/h)

2080 km/h120

Time-gap rule

2 s — dry 3 s — wet 4 s — fog/HGV 6 s — towing

Vehicles in convoy

Average vehicle length (m)

Conditions

Spacing & convoy length

— m gap to vehicle ahead

—

Time-gap applied—

Convoy total length—

Time across the convoy—

Recommended radio check—

For training purposes only. Journey risk thresholds and authorisation rules vary by company; defer to your operator's road-transport management standard.

47Defensive Driving Score (IOGP 365 weighted)

Score a driver's recent record across IOGP 365 risk factors. Weighted output: ≥ 80 = Green, 65–79 Amber, < 65 Red. Use during induction, periodic re-assessment, and post-incident.

Licence years

Annual mileage (km)

Incidents last 36 months

Speeding events last 12 months (telematics)

Defensive-driving training completed?

Vehicle type

Result

— / 100

—

Experience—

Exposure—

Incidents—

Behaviour—

Training—

Recommendation—

Reference: IOGP 365 — Land Transport Safety Recommended Practice (2021).

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Driving Safety Tools

14Stopping Distance Calculator

Result

15Journey Risk Assessment

Risk score

Mitigations

24Convoy Spacing & 2-Second Rule

Spacing & convoy length

47Defensive Driving Score (IOGP 365 weighted)

Result

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