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CrashStats

A4178 accidents: crash map and statistics

Police recorded 616 collisions on the A4178 from 1979 to 2025, with 825 casualties. Of those crashes, 5 were fatal and 107 serious, and 7 people were killed.

In 2025 there were 7 collisions on the A4178, up 17% from 6 in 2024, with 9 casualties.

Collisions since 1979
616
1,660th highest of 4,923 roads
Casualties
825
1.34 per collision
Fatal collisions
5
7 people killed
Serious collisions
107
127 seriously injured
Collisions in 2025
7
Up 17% on 2024
Casualties in 2025
9
Up 29% on 2024

Crash severity on the A4178

On the A4178, 0.8% of collisions were fatal and 17% serious, against 1.6% and 18% across Great Britain.

Collisions by severity, 1979 to 2025

  • Fatal50.8%
  • Serious10717%
  • Slight50482%

Where the A4178 ranks among 4,923 roads

Most collisions
1,660th
Most casualties
1,686th
Most fatal collisions
2,545th
Most serious collisions
1,804th

A4178 accidents by year

Collisions on the A4178 peaked at 26 in 1996 and were down to 7 in 2025.

Collisions and casualties on the A4178, 1979 to 2025

  • Collisions
  • Collisions in 2025: 7
  • Casualties

Source: Department for Transport, STATS19 road safety data

View as a table
YearCollisionsCasualties
202579
202467
20231119
202245
202133
202056
2019613
201879
201779
201633
2015910
20141112
201359
20121013
2011810
201089
20091017
2008813
20071218
20061013
20051524
20041317
20031423
20022431
20011727
20001421
19992227
19982025
19972429
19962632
19951829
19941826
19931722
19921625
19911315
1990910
19891012
19881415
19871216
19862635
19851718
19841414
19832125
19821926
19812432
19801414
19791528

When crashes happen on the A4178

Friday has the most collisions on the A4178 (104), and 3pm to 6pm is the busiest time of day (133).

Collisions by day of the week

  • Monday85 (14%)
  • Tuesday95 (15%)
  • Wednesday85 (14%)
  • Thursday86 (14%)
  • Friday104 (17%)
  • Saturday98 (16%)
  • Sunday63 (10%)

Collisions by time of day

  • Midnight to 3am36 (5.8%)
  • 3am to 6am10 (1.6%)
  • 6am to 9am85 (14%)
  • 9am to noon83 (13%)
  • Noon to 3pm96 (16%)
  • 3pm to 6pm133 (22%)
  • 6pm to 9pm111 (18%)
  • 9pm to midnight62 (10%)

Collisions by month

  • January57 (9.3%)
  • February51 (8.3%)
  • March49 (8%)
  • April54 (8.8%)
  • May52 (8.4%)
  • June41 (6.7%)
  • July50 (8.1%)
  • August47 (7.6%)
  • September54 (8.8%)
  • October52 (8.4%)
  • November57 (9.3%)
  • December52 (8.4%)

Light conditions at the time

  • Daylight412 (67%)
  • Dark, street lights lit195 (32%)
  • Dark, lighting unknown6 (1%)
  • Dark, street lights unlit3 (0.5%)

Source: Department for Transport, STATS19 road safety data

Road and weather conditions in A4178 crashes

On the A4178, 100% of collisions happened where the speed limit was 30 mph and 67% on a dry road surface.

Speed limit at the scene

  • 30 mph614 (100%)
  • 40 mph2 (0.3%)

Weather at the time

  • Fine, no high winds491 (80%)
  • Raining, no high winds83 (13%)
  • Raining with high winds7 (1.1%)
  • Snowing, no high winds4 (0.6%)
  • Other19 (3.1%)
  • Not recorded12 (1.9%)

Road surface

  • Dry412 (67%)
  • Wet or damp189 (31%)
  • Frost or ice5 (0.8%)
  • Snow4 (0.6%)
  • Oil or diesel1 (0.2%)
  • Not recorded5 (0.8%)

Type of road

  • Single carriageway483 (78%)
  • One way street or slip road90 (15%)
  • Dual carriageway41 (6.7%)
  • Not recorded2 (0.3%)

Source: Department for Transport, STATS19 road safety data

People hurt and vehicles involved in A4178 crashes

Car occupants make up 57% of the people killed or injured on the A4178, followed by pedestrians (18%).

Casualties by road user

  • Car occupant474 (57%)
  • Pedestrian147 (18%)
  • Motorcyclist87 (11%)
  • Cyclist82 (9.9%)
  • Van occupant13 (1.6%)
  • Taxi or private hire car occupant9 (1.1%)
  • Bus or coach occupant6 (0.7%)
  • Other7 (0.8%)

Vehicles involved

  • Car859 (76%)
  • Motorcycle92 (8.1%)
  • Pedal cycle84 (7.4%)
  • Van or goods vehicle up to 3.5 tonnes45 (4%)
  • Taxi or private hire car15 (1.3%)
  • Goods vehicle over 3.5 tonnes14 (1.2%)
  • Other23 (2%)
  • Not recorded1 (0.1%)

Casualties by age

  • 0 to 521 (2.5%)
  • 6 to 1031 (3.8%)
  • 11 to 1550 (6.1%)
  • 16 to 20150 (18%)
  • 21 to 25132 (16%)
  • 26 to 35179 (22%)
  • 36 to 4598 (12%)
  • 46 to 5561 (7.4%)
  • 56 to 6557 (6.9%)
  • 66 to 7519 (2.3%)
  • Over 7523 (2.8%)
  • Not recorded4 (0.5%)

Drivers, passengers and pedestrians

  • Driver or rider484 (59%)
  • Passenger194 (24%)
  • Pedestrian147 (18%)

Source: Department for Transport, STATS19 road safety data

Map of recent crashes on the A4178

Map of the 25 most recent crashes on the A4178

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

  • 25 crashes
  • Serious
  • Slight

A4178 crashes by council area

Collisions on the A4178 were recorded in 2 council areas. Watford has the most, with 613, followed by Three Rivers (3).

Collisions on the A4178 in each area, 1979 to 2025
RankAreaCollisionsCasualtiesFatalSerious
1stWatford6138225107
2ndThree Rivers3300

A4178 crashes by town

Of the 616 collisions on the A4178, 575 were in the built-up area of Watford, Watford.

Recent crashes on the A4178

These are the 25 most recent collisions on the A4178, from 5 November 2022 to 28 November 2025.

Severity