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CrashStats

A405 accidents: crash map and statistics

Police recorded 1,987 collisions on the A405 from 1979 to 2025, with 2,896 casualties. Of those crashes, 61 were fatal and 386 serious, and 63 people were killed.

In 2025 there were 16 collisions on the A405, up 7% from 15 in 2024, with 24 casualties.

Collisions since 1979
1,987
586th highest of 4,923 roads
Casualties
2,896
1.46 per collision
Fatal collisions
61
63 people killed
Serious collisions
386
481 seriously injured
Collisions in 2025
16
Up 7% on 2024
Casualties in 2025
24
Down 11% on 2024

Crash severity on the A405

On the A405, 3.1% of collisions were fatal and 19% serious, against 1.6% and 18% across Great Britain.

Collisions by severity, 1979 to 2025

  • Fatal613.1%
  • Serious38619%
  • Slight1,54078%

Where the A405 ranks among 4,923 roads

Most collisions
586th
Most casualties
551st
Most fatal collisions
342nd
Most serious collisions
556th

A405 accidents by year

Collisions on the A405 peaked at 110 in 1979 and were down to 16 in 2025.

Collisions and casualties on the A405, 1979 to 2025

  • Collisions
  • Collisions in 2025: 16
  • Casualties

Source: Department for Transport, STATS19 road safety data

View as a table
YearCollisionsCasualties
20251624
20241527
20232125
20222940
20212128
20201922
20192332
20182033
20172737
20163350
20152641
20142227
20132337
20122839
20113456
20103042
20093948
20084766
20074564
20064264
20053754
20043443
20033249
20023970
20014472
20004557
19994059
19983555
19972933
19964059
19953342
19943864
19933142
19922849
19913149
19903041
19893348
19885169
19872433
198692129
198592155
198489140
19836985
1982109160
198197149
198095122
1979110166

When crashes happen on the A405

Friday has the most collisions on the A405 (325), and 3pm to 6pm is the busiest time of day (447).

Collisions by day of the week

  • Monday294 (15%)
  • Tuesday296 (15%)
  • Wednesday287 (14%)
  • Thursday312 (16%)
  • Friday325 (16%)
  • Saturday245 (12%)
  • Sunday228 (11%)

Collisions by time of day

  • Midnight to 3am71 (3.6%)
  • 3am to 6am26 (1.3%)
  • 6am to 9am290 (15%)
  • 9am to noon286 (14%)
  • Noon to 3pm366 (18%)
  • 3pm to 6pm447 (22%)
  • 6pm to 9pm339 (17%)
  • 9pm to midnight162 (8.2%)

Collisions by month

  • January192 (9.7%)
  • February154 (7.8%)
  • March177 (8.9%)
  • April171 (8.6%)
  • May138 (6.9%)
  • June160 (8.1%)
  • July165 (8.3%)
  • August142 (7.1%)
  • September150 (7.5%)
  • October191 (9.6%)
  • November199 (10%)
  • December148 (7.4%)

Light conditions at the time

  • Daylight1,425 (72%)
  • Dark, street lights lit483 (24%)
  • Dark, no street lighting66 (3.3%)
  • Dark, lighting unknown11 (0.6%)
  • Dark, street lights unlit2 (0.1%)

Source: Department for Transport, STATS19 road safety data

Road and weather conditions in A405 crashes

On the A405, 44% of collisions happened where the speed limit was 70 mph and 62% on a dry road surface.

Speed limit at the scene

  • 20 mph1 (0.1%)
  • 30 mph41 (2.1%)
  • 40 mph251 (13%)
  • 50 mph660 (33%)
  • 60 mph169 (8.5%)
  • 70 mph865 (44%)

Weather at the time

  • Fine, no high winds1,568 (79%)
  • Raining, no high winds282 (14%)
  • Fine with high winds26 (1.3%)
  • Raining with high winds26 (1.3%)
  • Other59 (3%)
  • Not recorded26 (1.3%)

Road surface

  • Dry1,241 (62%)
  • Wet or damp708 (36%)
  • Frost or ice22 (1.1%)
  • Snow6 (0.3%)
  • Other3 (0.2%)
  • Not recorded7 (0.4%)

Type of road

  • Dual carriageway1,545 (78%)
  • Roundabout395 (20%)
  • Single carriageway28 (1.4%)
  • One way street or slip road16 (0.8%)
  • Not recorded3 (0.2%)

Source: Department for Transport, STATS19 road safety data

People hurt and vehicles involved in A405 crashes

Car occupants make up 74% of the people killed or injured on the A405, followed by motorcyclists (11%).

Casualties by road user

  • Car occupant2,137 (74%)
  • Motorcyclist305 (11%)
  • Pedestrian119 (4.1%)
  • Cyclist104 (3.6%)
  • Goods vehicle occupant (over 3.5 tonnes)96 (3.3%)
  • Van occupant82 (2.8%)
  • Other52 (1.8%)
  • Not recorded1 (under 0.1%)

Vehicles involved

  • Car3,035 (75%)
  • Goods vehicle over 3.5 tonnes313 (7.7%)
  • Motorcycle297 (7.3%)
  • Van or goods vehicle up to 3.5 tonnes208 (5.1%)
  • Pedal cycle105 (2.6%)
  • Bus or coach37 (0.9%)
  • Other64 (1.6%)
  • Not recorded1 (under 0.1%)

Casualties by age

  • 0 to 543 (1.5%)
  • 6 to 1057 (2%)
  • 11 to 15120 (4.1%)
  • 16 to 20415 (14%)
  • 21 to 25454 (16%)
  • 26 to 35638 (22%)
  • 36 to 45450 (16%)
  • 46 to 55302 (10%)
  • 56 to 65217 (7.5%)
  • 66 to 75116 (4%)
  • Over 7578 (2.7%)
  • Not recorded6 (0.2%)

Drivers, passengers and pedestrians

  • Driver or rider1,889 (65%)
  • Passenger888 (31%)
  • Pedestrian119 (4.1%)

Source: Department for Transport, STATS19 road safety data

Map of recent crashes on the A405

Map of the 25 most recent crashes on the A405

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

  • 25 crashes
  • Serious
  • Slight

A405 crashes by council area

Collisions on the A405 were recorded in 4 council areas. St Albans has the most, with 1,057, followed by Watford (498) and Three Rivers (407).

Collisions on the A405 in each area, 1979 to 2025
RankAreaCollisionsCasualtiesFatalSerious
1stSt Albans1,0571,50031203
2ndWatford4987491796
3rdThree Rivers4076151079
4thWelwyn Hatfield172237

A405 crashes by town

Collisions on the A405 were recorded in 6 towns and built-up areas, led by Watford, Watford (471) and Chiswell Green (78).

Recent crashes on the A405

These are the 25 most recent collisions on the A405, from 20 June 2024 to 14 December 2025.

Severity