Road collisions in Hertsmere
Police recorded 1,181 road collisions involving injury in Hertsmere between 2021 and 2025, about 236 a year. 19 of them were fatal, and an estimated 209 involved serious injury once DfT's severity adjustment is applied. These are reported injury collisions only: damage-only incidents and unreported injuries are not included.
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When collisions happen
The busiest hour was 8am to 9am, and 31% of collisions happened between 3pm and 7pm (fewer than the 32% across Great Britain). Thursday had the most collisions, and 26% happened at weekends.
Trend over time
Reported collisions went from 215 in 2021 to 221 in 2025, a very small change. Counts are affected by traffic levels, population and changes in how police record injuries, so Hertsmere should not be ranked against other areas on these numbers alone.
Who is affected
Across Hertsmere, 1,655 people were injured or killed in these collisions. Pedestrians were 9% of casualties (14% across Great Britain), pedal cyclists 5% (12%) and motorcyclists 10% (12%). Car and taxi occupants made up 69%. 4 of the pedestrians were killed.
Children aged 0 to 15 were 6% of casualties, lower than the 9% national share. People aged 16 to 25 were 19% (21% nationally), and people over 65 were 9% (10% nationally).
| Road user | Casualties | Share in Hertsmere | Share across GB |
|---|---|---|---|
| Pedestrians | 154 | 9.3% | 14.5% |
| Pedal cyclists | 90 | 5.4% | 11.9% |
| Motorcyclists | 165 | 10.0% | 12.4% |
| Car and taxi occupants | 1,134 | 68.5% | 54.4% |
| Bus and minibus occupants | 9 | 0.5% | 1.8% |
| Van and goods vehicle occupants | 86 | 5.2% | 3.5% |
| Other road users | 17 | 1.0% | 1.6% |
Casualties by age
| Age | Casualties | Share in Hertsmere | Share across GB |
|---|---|---|---|
| 0 to 5 | 24 | 1.5% | 1.6% |
| 6 to 10 | 30 | 1.9% | 2.6% |
| 11 to 15 | 50 | 3.1% | 4.8% |
| 16 to 20 | 122 | 7.6% | 10.6% |
| 21 to 25 | 198 | 12.3% | 11.0% |
| 26 to 35 | 343 | 21.3% | 20.8% |
| 36 to 45 | 321 | 19.9% | 15.8% |
| 46 to 55 | 227 | 14.1% | 12.8% |
| 56 to 65 | 147 | 9.1% | 10.1% |
| 66 to 75 | 88 | 5.5% | 5.3% |
| Over 75 | 60 | 3.7% | 4.5% |
Vehicles involved
12.8% of collisions involved a pedestrian casualty (17.7% nationally), 7.5% a cyclist (15.0%) and 13.8% a motorcyclist (15.3%). 7.9% involved a goods vehicle (3.9% nationally) and 20.2% involved a driver aged 17 to 24 (21.1%). 14 collisions involved an e-scooter.
| Vehicle | Vehicles | Share in Hertsmere | Share across GB |
|---|---|---|---|
| Cars and taxis | 1,734 | 73.9% | 69.7% |
| Vans (up to 3.5 tonnes) | 190 | 8.1% | 6.4% |
| Heavy goods vehicles | 104 | 4.4% | 2.3% |
| Motorcycles | 172 | 7.3% | 9.3% |
| Pedal cycles | 92 | 3.9% | 8.7% |
| Buses and minibuses | 13 | 0.6% | 1.8% |
| Other vehicles | 42 | 1.8% | 1.8% |
Collision hotspots in Hertsmere
These are the 100 metre squares with the most reported collisions in 2021 to 2025. Location is the average position of the collisions in each square, so treat it as approximate.
| # | Main road | Junction type | Collisions | Fatal | Map |
|---|---|---|---|---|---|
| 1 | B462 | Roundabout | 12 | 0 | View on map |
| 2 | A41 | Roundabout | 11 | 0 | View on map |
| 3 | M25 | Not at a junction | 8 | 0 | View on map |
| 4 | A1005 | Roundabout | 8 | 0 | View on map |
| 5 | B5378 | Not at a junction | 8 | 0 | View on map |
| 6 | B5378 | Not at a junction | 7 | 0 | View on map |
| 7 | A1 | Roundabout | 7 | 0 | View on map |
| 8 | A(M)1 | Not at a junction | 6 | 0 | View on map |
| 9 | B5378 | Roundabout | 6 | 0 | View on map |
| 10 | A41 | T or staggered junction | 6 | 0 | View on map |
| 11 | A41 | Roundabout | 6 | 0 | View on map |
| 12 | A111 | Roundabout | 6 | 0 | View on map |
| 13 | Unnumbered road | T or staggered junction | 6 | 0 | View on map |
| 14 | B462 | Roundabout | 6 | 0 | View on map |
| 15 | A1081 | Roundabout | 6 | 0 | View on map |
| 16 | A4008 | Roundabout | 6 | 0 | View on map |
| 17 | A1000 | T or staggered junction | 6 | 0 | View on map |
| 18 | A1000 | T or staggered junction | 6 | 0 | View on map |
| 19 | B462 | Crossroads | 6 | 0 | View on map |
| 20 | A1000 | T or staggered junction | 5 | 0 | View on map |
| 21 | A5183 | Not at a junction | 5 | 0 | View on map |
| 22 | A41 | Not at a junction | 5 | 0 | View on map |
| 23 | B556 | Roundabout | 5 | 0 | View on map |
| 24 | A411 | Crossroads | 5 | 0 | View on map |
| 25 | A4008 | Roundabout | 5 | 0 | View on map |
Numbered roads with the most collisions
52% of collisions happened on roads with a 30 mph limit or lower (69% nationally), and 35% on roads with a 60 or 70 mph limit (18% nationally). 42% were at or within 20 metres of a junction or roundabout, lower than the national 54%.
| Road | Collisions | Fatal | Serious (est.) |
|---|---|---|---|
| M25 | 131 | 1 | 13 |
| A1 | 75 | 2 | 11 |
| A41 | 67 | 1 | 13 |
| M1 | 66 | 2 | 6 |
| A411 | 59 | 0 | 14 |
| A5183 | 54 | 3 | 12 |
| B5378 | 52 | 0 | 9 |
| B462 | 47 | 0 | 7 |
| A4008 | 37 | 1 | 2 |
| A1000 | 35 | 0 | 8 |
| B556 | 34 | 0 | 16 |
| A5135 | 24 | 0 | 1 |
| A1081 | 21 | 0 | 3 |
| A(M)1 | 20 | 2 | 5 |
| A111 | 19 | 1 | 2 |
Collisions on unnumbered local streets are not listed here. Use the postcode search to see them.
Conditions
28% of collisions in Hertsmere happened in darkness, close to the 28% across Great Britain. 41% happened on roads classed as urban, lower than the national 67%.
Type of road
| Type of road | Collisions | Share in Hertsmere | Share across GB |
|---|---|---|---|
| Motorway | 197 | 16.7% | 3.0% |
| A(M) road | 20 | 1.7% | 0.2% |
| A road | 416 | 35.2% | 44.0% |
| B road | 133 | 11.3% | 12.5% |
| C road | 0 | 0.0% | 4.4% |
| Unclassified road | 415 | 35.1% | 35.9% |
Speed limit
| Speed limit | Collisions | Share in Hertsmere | Share across GB |
|---|---|---|---|
| 20 mph | 42 | 3.6% | 17.1% |
| 30 mph | 578 | 48.9% | 52.0% |
| 40 mph | 99 | 8.4% | 8.7% |
| 50 mph | 54 | 4.6% | 4.4% |
| 60 mph | 145 | 12.3% | 12.2% |
| 70 mph | 263 | 22.3% | 5.5% |
Junctions
| Junctions | Collisions | Share in Hertsmere | Share across GB |
|---|---|---|---|
| Not at a junction | 683 | 58.4% | 45.9% |
| T or staggered junction | 250 | 21.4% | 28.5% |
| Crossroads | 39 | 3.3% | 9.5% |
| Junction with more than four arms | 6 | 0.5% | 1.6% |
| Private drive or entrance | 6 | 0.5% | 2.2% |
| Other junction | 38 | 3.2% | 6.1% |
| Roundabout | 148 | 12.6% | 6.2% |
Light conditions
| Light conditions | Collisions | Share in Hertsmere | Share across GB |
|---|---|---|---|
| Daylight | 853 | 72.2% | 71.7% |
| Darkness, street lights lit | 236 | 20.0% | 20.6% |
| Darkness, street lights unlit | 13 | 1.1% | 0.7% |
| Darkness, no street lighting | 53 | 4.5% | 5.3% |
| Darkness, lighting unknown | 26 | 2.2% | 1.7% |
Urban or rural
| Urban or rural | Collisions | Share in Hertsmere | Share across GB |
|---|---|---|---|
| Urban | 488 | 41.3% | 67.2% |
| Rural | 693 | 58.7% | 32.8% |
About these figures
Only collisions involving injury that were reported to the police are counted. The figures are not adjusted for traffic volume or population, so they should not be used to rank areas against each other. Serious and slight splits use the Department for Transport's severity adjustment. Full explanation.