How Safety Scores Work
A transparent, data-driven look at how we evaluate route safety — so you can travel with confidence.
The Big Picture
When you search for a route on Tranzia, we don't just show you the fastest path. We analyze every segment of your journey and generate a 0–10 safety score based on real data, environmental conditions, and traveler feedback.
| Factor | Weight | What It Measures |
|---|---|---|
| 🔴 Crime Data | 55% | Historical incident patterns along your route |
| 🌙 Time of Day | 20% | Nighttime visibility and crowd levels |
| 👣 Walking Exposure | 15% | Street-level exposure based on walk time |
| 💬 User Feedback | 10% | How travelers felt using this route |
1. Crime Data (55%)
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:
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)
2. Time of Day (20%)
Safety shifts dramatically after dark:
- Fewer people around
- Reduced visibility
- Quieter train platforms and station corridors
If 8 PM – 5 AM → Night penalty = 0.4
Otherwise → No penalty
A route that's 8.5/10 during the day may drop to 7.7/10 at night.
3. 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
A 15-minute nighttime walk has more impact than a 5-minute one.
4. User Feedback (10%)
Tranzia gets smarter every time users contribute feedback.
We require at least 5 reports before feedback affects scoring. Older reports decay over time, and official data always remains primary.
At 10% weight, trolls can't poison good areas — but real patterns emerge over time.
The Formula
Total Danger =
(Crime × 0.55) +
(Time × 0.20) +
(Walk × 0.15) +
(Feedback × 0.10)
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.