How Safety Scores Work
A transparent, data-driven look at how we evaluate route safety — so you can travel with confidence.
The Factors Framework
We don't just count crimes. We analyze the **Safety Trinity**: Social (Crime), Physical (Traffic), and Environmental (Light).
Social Safety
Official crime reports (Theft, Assault). Modeled for statistical density.
Physical Safety
Vision Zero data. "Killer Intersections" and high-injury zones are penalized.
Luminosity
Context matters. Night penalties apply, but Well-Lit Streets get a "Bright Mode Bonus."
Exposure
Street-level vulnerability. Longer walks at night increase risk.
Feedback
We collect user reports, but they don't affect scores yet.
Real World Examples
Scenario A: The "Bright" Path ☀️
11:00 PM • Main Street
Scenario B: The "Killer Intersection" 🚦
2:00 PM • Busy Junction
1. Social Safety (Crime) (40%)
Crime data is the backbone of the score.
Where it comes from
- London: Police.uk street-level incident reports (monthly updates)
- NYC: NYPD CompStat and precinct-level datasets
How we process it
We map cities into small hexagonal cells (~174m across) and normalize crime counts using percentiles. Crucially, we also model "Ambient Density" for safe areas to account for unreported quality-of-life issues.
Top 5% crime areas → High danger (0.8–1.0)
Average areas → Medium danger (0.4–0.6)
Bottom 25% areas → Low danger (0.0–0.2)
Global Consistency: Apples to Apples
Every city reports crime differently. London includes "Anti-Social Behavior" (noise, loitering), while NYC focuses on "Major Felonies". If we compared raw numbers directly, NYC would look artificially safer than it really is.
Our Harmonization Promise
We calibrate every city individually. A 9.0 Score in Tokyo means the same thing as a 9.0 Score in New York: "Top-tier safety relative to this environment."
2. Physical Safety (Traffic) (20%)
Traffic accidents are a major urban danger.
- London: TfL Stats19 data tracks injury collisions
- NYC: Motor Vehicle Collisions (Vision Zero)
High Injury Zone → -3.0 Penalty
Medium Risk Zone → -1.5 Penalty
3. Luminosity (Time & Light) (15%)
Darkness increases risk, but lights mitigate it.
- Street lamp density (OSM)
- Time of day execution
Night (8 PM - 5 AM) → Base Penalty
Well-Lit Area → "Bright Mode" (+bonus)
Dark Area → Double Penalty
4. Walking Exposure (15%)
Walking keeps you at street level, exposed to your surroundings.
Walking danger = (walk minutes) / 33
Maximum = 0.5
Applies at night only
5. User Feedback (Display Only)
We collect user feedback but it does not currently affect scores.
Once we have sufficient volume (5+ reports per segment), feedback may be introduced at a small weight with abuse controls and time decay.
For now, this helps us validate data quality — not influence scores.
The Formula
Total Danger =
(Crime × 0.40) +
(Traffic × 0.20) +
(Time/Light × 0.15) +
(Walk × 0.15) +
(Feedback × 0.10) — not active yet
Safety Score = 10 − (Total Danger × 10)
What the Scores Mean
8–10: Low Risk
Generally safe, well-traveled routes
4–7: Caution
Some risk factors — stay alert
0–4: Elevated Risk
Consider alternatives or extra precautions
Our Commitment to Transparency
Tranzia is built on:
- Open data from official sources
- Clear methodology you can understand
- Community insights that improve accuracy over time
- Honest, objective assessments — never fearmongering
This is not a black box. You deserve to know how the score is produced.
What We Don't Do
- ❌ We do not guarantee safety — conditions change
- ❌ We do not track your location
- ❌ We never use demographic or personal data
- ❌ We do not replace your own judgment
Tranzia is a tool — you remain the final expert on your surroundings.