The science behind
safer driving.

Traffic psychology is the scientific study of driver behaviour, decision-making and risk — and the interventions that actually reduce road deaths.

This guide covers the full picture: how your brain processes a driving situation, what happens when alcohol, speed, phones or fatigue intervene, why certain groups are more at risk, and what Irish and EU policy has proven to work.

Texting in an HGV is 23× more dangerous than alert driving — more dangerous than being over the alcohol limit. Eyes off the road for 2 seconds doubles your crash risk at any speed.

This guide covers the four types of distraction, how attention works, Irish crash data, phone law, category-specific risks for Cat B / C / D drivers, and a 6-point pre-drive checklist.

Over 90% of crashes involve a human factor — yet most drivers believe they are above average. Based on Shinar's Traffic Safety and Human Behavior (2nd Ed.) and supplemented by WHO, ETSC, and RSA Ireland official data.

Covers the global scale, crash causation models, the hierarchical driver model, speed and alcohol science, distraction types, fatigue and micro-sleeps, vulnerable road users, the Safe System approach, and evidence-based countermeasures.

Speed is not just a legal issue — it's a physics issue. Kinetic energy increases with the square of speed, meaning a 20% speed increase produces a 44% increase in impact energy.

This guide covers Nilsson's power model, pedestrian survival curves, Irish crash data on speed as a causal factor, and how Vision Zero's Safe System approach uses biomechanical limits to set survivable speeds.

Fatigue contributes to 1 in 5 fatal crashes in Ireland — and a 5-second microsleep at 100 km/h covers 139 metres with zero driver control.

This guide covers the neuroscience of sleep deprivation, BAC-equivalent impairment evidence, circadian crash timing, tachograph rest obligations for HGV/PSV drivers, and what the research shows actually works as a countermeasure.

70% of Irish driver fatalities between 10pm and 6am test positive for alcohol. Cannabis + alcohol produces 14× the crash risk of sober driving.

This guide covers how alcohol and drugs impair the driving brain, the dose-response crash risk curve, all Irish BAC limits by licence category, the DRUID study's drug-by-drug risk multipliers, and 8,863 Irish arrests in 2023.

70% of Irish fatalities occur on roads with 80 km/h limits or greater. Converting a priority junction to a roundabout reduces fatal crashes by up to 75–90%.

This guide covers expert vs novice hazard scanning science, junction type safety evidence, iRAP 1–5 star road ratings, the Safe System design framework, and why rural roads kill disproportionately more than motorways.

Only 10% of miles are driven at night — yet 40% of fatal crashes occur in darkness. At 100 km/h on low beam, you cannot stop in the distance your headlights illuminate.

This guide covers the physics of stopping distance vs headlight range, glare physiology, dark adaptation, pedestrian conspicuity science, and the Adaptive Driving Beam technology now mandated by EU Regulation 2019/2144.

Wet roads double minimum stopping distances — but two-thirds of drivers don't adjust. Ice reduces friction by 85–95%, extending stopping distance at 80 km/h from 58m to over 400m.

This guide covers the physics and data behind weather-related crash risk, a full stopping distance table by speed and surface condition, aquaplaning onset speeds, tyre tread science, and Irish fog light legal requirements.

26% of Irish road fatalities in 2023 were aged 16–25. One peer passenger doubles crash risk; two or more quadruples it. Inexperience — not youth — explains most of the elevated risk.

This guide covers the neuroscience of the adolescent brain, crash rate experience curves, peer passenger research, risk homeostasis theory, and the evidence base for Graduated Driver Licensing programmes.

Rollover crashes account for 33% of all traffic fatalities while representing only 3% of crashes. Doubling cornering speed requires 4× the grip from the same tyre contact patch.

This guide covers the physics of every cornering manoeuvre, the understeer vs oversteer distinction, how ESC works, and why loaded HGVs can roll at just 0.2g of lateral acceleration — compared to 0.8g+ for a passenger car.

174 people died on Irish roads in 2024. 90% of crashes involve a human factor — but most also have a concurrent road or vehicle factor. Speed contributes to 30–35% of fatals; alcohol to 25–30%.

This guide covers crash reconstruction science, EDR data, Ireland's full 2019–2024 fatality record, the EU CARE and ERSO databases, contributory factor breakdown, and progress against the EU 2050 Vision Zero target.