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CrashStats

A4147 accidents: crash map and statistics

Police recorded 1,281 collisions on the A4147 from 1979 to 2025, with 1,742 casualties. Of those crashes, 19 were fatal and 247 serious, and 20 people were killed.

In 2025 there were 8 collisions on the A4147, down 38% from 13 in 2024, with 11 casualties.

Collisions since 1979
1,281
861st highest of 4,923 roads
Casualties
1,742
1.36 per collision
Fatal collisions
19
20 people killed
Serious collisions
247
286 seriously injured
Collisions in 2025
8
Down 38% on 2024
Casualties in 2025
11
Down 39% on 2024

Crash severity on the A4147

On the A4147, 1.5% of collisions were fatal and 19% serious, against 1.6% and 18% across Great Britain.

Collisions by severity, 1979 to 2025

  • Fatal191.5%
  • Serious24719%
  • Slight1,01579%

Where the A4147 ranks among 4,923 roads

Most collisions
861st
Most casualties
850th
Most fatal collisions
1,031st
Most serious collisions
870th

A4147 accidents by year

Collisions on the A4147 peaked at 60 in 1995 and were down to 8 in 2025.

Collisions and casualties on the A4147, 1979 to 2025

  • Collisions
  • Collisions in 2025: 8
  • Casualties

Source: Department for Transport, STATS19 road safety data

View as a table
YearCollisionsCasualties
2025811
20241318
2023913
20221219
20211520
2020910
20191418
20181212
20171212
20162326
20151521
20141925
20131926
20122436
20112831
20102227
20091725
20082023
20073152
20062934
20053253
20043241
20033651
20024668
20014574
20005273
19993750
19985277
19974259
19963249
19956072
19943849
19933846
19923453
19913651
19904556
19892940
19881831
19871924
19862431
19851419
19842841
19832833
19822025
19812735
19803042
19793640

When crashes happen on the A4147

Wednesday has the most collisions on the A4147 (223), and 3pm to 6pm is the busiest time of day (289).

Collisions by day of the week

  • Monday172 (13%)
  • Tuesday212 (17%)
  • Wednesday223 (17%)
  • Thursday202 (16%)
  • Friday199 (16%)
  • Saturday163 (13%)
  • Sunday110 (8.6%)

Collisions by time of day

  • Midnight to 3am41 (3.2%)
  • 3am to 6am30 (2.3%)
  • 6am to 9am219 (17%)
  • 9am to noon172 (13%)
  • Noon to 3pm211 (16%)
  • 3pm to 6pm289 (23%)
  • 6pm to 9pm207 (16%)
  • 9pm to midnight112 (8.7%)

Collisions by month

  • January116 (9.1%)
  • February97 (7.6%)
  • March125 (9.8%)
  • April88 (6.9%)
  • May106 (8.3%)
  • June93 (7.3%)
  • July95 (7.4%)
  • August107 (8.4%)
  • September108 (8.4%)
  • October120 (9.4%)
  • November124 (9.7%)
  • December102 (8%)

Light conditions at the time

  • Daylight900 (70%)
  • Dark, street lights lit297 (23%)
  • Dark, no street lighting54 (4.2%)
  • Dark, lighting unknown22 (1.7%)
  • Dark, street lights unlit8 (0.6%)

Source: Department for Transport, STATS19 road safety data

Road and weather conditions in A4147 crashes

On the A4147, 58% of collisions happened where the speed limit was 30 mph and 58% on a dry road surface.

Speed limit at the scene

  • 20 mph1 (0.1%)
  • 30 mph746 (58%)
  • 40 mph190 (15%)
  • 50 mph97 (7.6%)
  • 60 mph206 (16%)
  • 70 mph41 (3.2%)

Weather at the time

  • Fine, no high winds975 (76%)
  • Raining, no high winds208 (16%)
  • Raining with high winds19 (1.5%)
  • Fog or mist14 (1.1%)
  • Other55 (4.3%)
  • Not recorded10 (0.8%)

Road surface

  • Dry743 (58%)
  • Wet or damp504 (39%)
  • Frost or ice20 (1.6%)
  • Snow6 (0.5%)
  • Other5 (0.4%)
  • Not recorded3 (0.2%)

Type of road

  • Single carriageway1,033 (81%)
  • Roundabout164 (13%)
  • Dual carriageway72 (5.6%)
  • One way street or slip road11 (0.9%)
  • Not recorded1 (0.1%)

Source: Department for Transport, STATS19 road safety data

People hurt and vehicles involved in A4147 crashes

Car occupants make up 66% of the people killed or injured on the A4147, followed by motorcyclists (14%).

Casualties by road user

  • Car occupant1,153 (66%)
  • Motorcyclist238 (14%)
  • Pedestrian133 (7.6%)
  • Cyclist122 (7%)
  • Van occupant52 (3%)
  • Goods vehicle occupant (over 3.5 tonnes)20 (1.1%)
  • Bus or coach occupant9 (0.5%)
  • Other15 (0.9%)

Vehicles involved

  • Car1,901 (75%)
  • Motorcycle241 (9.5%)
  • Pedal cycle125 (4.9%)
  • Van or goods vehicle up to 3.5 tonnes112 (4.4%)
  • Goods vehicle over 3.5 tonnes82 (3.2%)
  • Taxi or private hire car24 (0.9%)
  • Other vehicle17 (0.7%)
  • Other25 (1%)

Casualties by age

  • 0 to 518 (1%)
  • 6 to 1048 (2.8%)
  • 11 to 1554 (3.1%)
  • 16 to 20329 (19%)
  • 21 to 25250 (14%)
  • 26 to 35412 (24%)
  • 36 to 45226 (13%)
  • 46 to 55196 (11%)
  • 56 to 65109 (6.3%)
  • 66 to 7570 (4%)
  • Over 7526 (1.5%)
  • Not recorded4 (0.2%)

Drivers, passengers and pedestrians

  • Driver or rider1,212 (70%)
  • Passenger397 (23%)
  • Pedestrian133 (7.6%)

Source: Department for Transport, STATS19 road safety data

Map of recent crashes on the A4147

Map of the 25 most recent crashes on the A4147

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

  • 25 crashes
  • Fatal
  • Serious
  • Slight

A4147 crashes by council area

Collisions on the A4147 were recorded in 3 council areas. Dacorum has the most, with 933, followed by St Albans (338) and South Gloucestershire (5).

Collisions on the A4147 in each area, 1979 to 2025
RankAreaCollisionsCasualtiesFatalSerious
1stDacorum9331,2518167
2ndSt Albans3384781080
3rdSouth Gloucestershire5710

A4147 crashes by town

Collisions on the A4147 were recorded in 2 towns and built-up areas, led by Hemel Hempstead (842) and St Albans (110).

Recent crashes on the A4147

These are the 25 most recent collisions on the A4147, from 7 September 2023 to 15 December 2025.

Severity