Driving/Data

Distance & Baseline Rates

Distance choice	Miles	Thousands of miles (multiplier)	Baseline fatalities per 1,000 miles	Baseline serious injuries per 1,000 miles
100 miles	100	0.1	0.0000126	0.00075
1,000 miles	1000	1	0.0000126	0.00075
100,000 miles	100000	100	0.0000126	0.00075

Baseline fatality rate (2023): **1.26 deaths per 100 million VMT** → **0.0126 per 1,000 miles**. Baseline injury rate (2022): **75 injuries per 100 million VMT** → **0.75 per 1,000 miles**.

• NHTSA 2023 Traffic Fatalities Estimates
• IIHS: Fatality statistics (rates per VMT)
• NHTSA: Traffic Safety Facts 2022 (injury rates)

Time of Day (Modifier)

Time of day	Fatality risk multiplier	Injury risk multiplier
Day	1.0	1.0
Night	3.56	1.47

Per-mile risk is higher at night: in 2022, ~53.9% of fatalities and ~32.9% of injury crashes occurred in night hours while ~25% of VMT occurs at night, yielding ≈3.56× (fatalities) and ≈1.47× (injuries).

• NHTSA: 2022 crash statistics
• NHTSA: Time of day & crash involvement
• Exposure assumption: ~25% of VMT at night (FHWA Lighting Guidance)

Seat-belt Usage (Modifier)

Seat-belt usage	Fatality risk multiplier	Injury risk multiplier
Worn (car)	1.0	1.0
Not worn (car)	1.82	2.0
Worn (SUV/van/truck)	1.0	1.0
Not worn (SUV/van/truck)	2.5	2.857

Seat belts reduce fatal injury risk by ~45% in cars and ~60% in light trucks; moderate-to-critical injury by ~50% in cars and ~65% in light trucks. Multipliers above are the inverse of those reductions.

• IIHS: Seat belts
• NHTSA: Seat belt effectiveness

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  RiskModel: Driving/Data:fatality_model
Calculation: base_fatalities_per_1000_miles * distance_thousand_miles * time_fatality_multiplier * belt_fatality_multiplier
    Content: 
Your estimated fatality risk for {distance_label} is about {result}.

  RiskModel: Driving/Data:injury_model
Calculation: base_injuries_per_1000_miles * distance_thousand_miles * time_injury_multiplier * belt_injury_multiplier
    Content: 
Your estimated serious injury risk for {distance_label} is about {result}.

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Note on uncertainty: These values are national averages and should be seen as approximate indicators. Actual risks vary by roadway type (urban/rural), vehicle, weather, geography, and year. Multipliers are population-level and may not predict individual outcomes.

Generated by ChatGPT-5