Percentage reduction in casualties in 20 mph zones
| Severity | Percentage reduction in casualties in 20 mph zones (95% CI) | Average annual percentage reduction in casualties (95% CI) |
|---|---|---|
| Fatal | 56.5% (17.2% to 95.8%) | 4.3% (1.5% to 7.0%) |
| Serious | 26.2% (14.4% to 38.1%) | 7.9% (7.2% to 8.6%) |
| Slight | 21.7% (13.7% to 29.6%) | 6.2% (5.6% to 6.7%) |