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CrashStats

A4251 accidents: crash map and statistics

Police recorded 1,227 collisions on the A4251 from 1979 to 2025, with 1,744 casualties. Of those crashes, 17 were fatal and 241 serious, and 18 people were killed.

In 2025 there were 17 collisions on the A4251, down 11% from 19 in 2024, with 20 casualties.

Collisions since 1979
1,227
899th highest of 4,923 roads
Casualties
1,744
1.42 per collision
Fatal collisions
17
18 people killed
Serious collisions
241
286 seriously injured
Collisions in 2025
17
Down 11% on 2024
Casualties in 2025
20
Down 9% on 2024

Crash severity on the A4251

On the A4251, 1.4% of collisions were fatal and 20% serious, against 1.6% and 18% across Great Britain.

Collisions by severity, 1979 to 2025

  • Fatal171.4%
  • Serious24120%
  • Slight96979%

Where the A4251 ranks among 4,923 roads

Most collisions
899th
Most casualties
849th
Most fatal collisions
1,125th
Most serious collisions
888th

A4251 accidents by year

Collisions on the A4251 peaked at 69 in 1999 and were down to 17 in 2025.

Collisions and casualties on the A4251, 1979 to 2025

  • Collisions
  • Collisions in 2025: 17
  • Casualties

Source: Department for Transport, STATS19 road safety data

View as a table
YearCollisionsCasualties
20251720
20241922
20232031
20221923
20211419
20201526
20191114
20181823
20172230
20162438
20152028
20143042
20132329
20122635
20113452
20103138
20093348
20083152
20074673
20063850
20052841
20043762
20034977
20024059
20015376
20005676
19996994
19985172
19975474
19965495
19955782
19945264
19932435
199200
1991612
1990613
19891214
198879
1987912
19861012
19851112
198478
19831012
19821011
19811012
1980911
197956

When crashes happen on the A4251

Friday has the most collisions on the A4251 (224), and 3pm to 6pm is the busiest time of day (277).

Collisions by day of the week

  • Monday153 (12%)
  • Tuesday152 (12%)
  • Wednesday183 (15%)
  • Thursday188 (15%)
  • Friday224 (18%)
  • Saturday189 (15%)
  • Sunday138 (11%)

Collisions by time of day

  • Midnight to 3am31 (2.5%)
  • 3am to 6am14 (1.1%)
  • 6am to 9am171 (14%)
  • 9am to noon192 (16%)
  • Noon to 3pm212 (17%)
  • 3pm to 6pm277 (23%)
  • 6pm to 9pm218 (18%)
  • 9pm to midnight112 (9.1%)

Collisions by month

  • January112 (9.1%)
  • February104 (8.5%)
  • March119 (9.7%)
  • April92 (7.5%)
  • May99 (8.1%)
  • June112 (9.1%)
  • July99 (8.1%)
  • August73 (5.9%)
  • September100 (8.1%)
  • October96 (7.8%)
  • November110 (9%)
  • December111 (9%)

Light conditions at the time

  • Daylight873 (71%)
  • Dark, street lights lit293 (24%)
  • Dark, no street lighting41 (3.3%)
  • Dark, lighting unknown12 (1%)
  • Dark, street lights unlit8 (0.7%)

Source: Department for Transport, STATS19 road safety data

Road and weather conditions in A4251 crashes

On the A4251, 73% of collisions happened where the speed limit was 30 mph and 65% on a dry road surface.

Speed limit at the scene

  • 20 mph19 (1.5%)
  • 30 mph898 (73%)
  • 40 mph97 (7.9%)
  • 50 mph2 (0.2%)
  • 60 mph207 (17%)
  • 70 mph4 (0.3%)

Weather at the time

  • Fine, no high winds971 (79%)
  • Raining, no high winds164 (13%)
  • Fine with high winds15 (1.2%)
  • Fog or mist8 (0.7%)
  • Other58 (4.7%)
  • Not recorded11 (0.9%)

Road surface

  • Dry794 (65%)
  • Wet or damp396 (32%)
  • Frost or ice25 (2%)
  • Snow5 (0.4%)
  • Flood over 3cm deep1 (0.1%)
  • Not recorded6 (0.5%)

Type of road

  • Single carriageway1,125 (92%)
  • Roundabout72 (5.9%)
  • Dual carriageway22 (1.8%)
  • One way street or slip road6 (0.5%)
  • Not recorded2 (0.2%)

Source: Department for Transport, STATS19 road safety data

People hurt and vehicles involved in A4251 crashes

Car occupants make up 66% of the people killed or injured on the A4251, followed by motorcyclists (14%).

Casualties by road user

  • Car occupant1,154 (66%)
  • Motorcyclist238 (14%)
  • Pedestrian153 (8.8%)
  • Cyclist118 (6.8%)
  • Van occupant29 (1.7%)
  • Taxi or private hire car occupant17 (1%)
  • Other34 (1.9%)
  • Not recorded1 (0.1%)

Vehicles involved

  • Car1,843 (76%)
  • Motorcycle239 (9.9%)
  • Pedal cycle121 (5%)
  • Van or goods vehicle up to 3.5 tonnes103 (4.3%)
  • Goods vehicle over 3.5 tonnes45 (1.9%)
  • Bus or coach29 (1.2%)
  • Other36 (1.5%)
  • Not recorded3 (0.1%)

Casualties by age

  • 0 to 521 (1.2%)
  • 6 to 1041 (2.4%)
  • 11 to 1566 (3.8%)
  • 16 to 20379 (22%)
  • 21 to 25226 (13%)
  • 26 to 35329 (19%)
  • 36 to 45243 (14%)
  • 46 to 55170 (9.7%)
  • 56 to 65121 (6.9%)
  • 66 to 7563 (3.6%)
  • Over 7569 (4%)
  • Not recorded16 (0.9%)

Drivers, passengers and pedestrians

  • Driver or rider1,181 (68%)
  • Passenger410 (24%)
  • Pedestrian153 (8.8%)

Source: Department for Transport, STATS19 road safety data

Map of recent crashes on the A4251

Map of the 25 most recent crashes on the A4251

Use the arrow keys to move the map and the plus and minus keys to zoom.

  • 25 crashes
  • Serious
  • Slight

A4251 crashes by council area

Of the 1,227 collisions on the A4251, 1,219 were in Dacorum.

Collisions on the A4251 in each area, 1979 to 2025
RankAreaCollisionsCasualtiesFatalSerious
1stDacorum1,2191,73417237

A4251 crashes by town

Collisions on the A4251 were recorded in 5 towns and built-up areas, led by Hemel Hempstead (284) and Berkhamsted (266).

Recent crashes on the A4251

These are the 25 most recent collisions on the A4251, from 1 June 2024 to 4 December 2025.

Severity