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CrashStats

B4366 accidents: crash map and statistics

Police recorded 289 collisions on the B4366 from 1979 to 2025, with 439 casualties. Of those crashes, 5 were fatal and 68 serious, and 5 people were killed.

In 2025 there was 1 collision on the B4366, level with 2024, with 1 casualty.

Collisions since 1979
289
2,749th highest of 4,923 roads
Casualties
439
1.52 per collision
Fatal collisions
5
5 people killed
Serious collisions
68
89 seriously injured
Collisions in 2025
1
Level with 2024
Casualties in 2025
1
Level with 2024

Crash severity on the B4366

On the B4366, 1.7% of collisions were fatal and 24% serious, against 1.6% and 18% across Great Britain.

Collisions by severity, 1979 to 2025

  • Fatal51.7%
  • Serious6824%
  • Slight21675%

Where the B4366 ranks among 4,923 roads

Most collisions
2,749th
Most casualties
2,591st
Most fatal collisions
2,545th
Most serious collisions
2,523rd

B4366 accidents by year

Collisions on the B4366 peaked at 23 in 1997 and were down to 1 in 2025.

Collisions and casualties on the B4366, 1979 to 2025

  • Collisions
  • Collisions in 2025: 1
  • Casualties

Source: Department for Transport, STATS19 road safety data

View as a table
YearCollisionsCasualties
202511
202411
202300
202200
202100
202000
201900
201811
201722
201611
201511
201433
201322
201200
201122
201044
200933
200845
200748
200623
200525
2004412
2003811
2002710
200167
20001627
19991524
19981324
19972331
19961115
19951326
19941433
1993912
19921419
19911629
199078
19891013
198845
1987914
198678
198535
198456
198357
1982813
198168
1980911
19791419

When crashes happen on the B4366

Friday has the most collisions on the B4366 (46), and 3pm to 6pm is the busiest time of day (72).

Collisions by day of the week

  • Monday44 (15%)
  • Tuesday45 (16%)
  • Wednesday41 (14%)
  • Thursday45 (16%)
  • Friday46 (16%)
  • Saturday35 (12%)
  • Sunday33 (11%)

Collisions by time of day

  • Midnight to 3am6 (2.1%)
  • 3am to 6am2 (0.7%)
  • 6am to 9am33 (11%)
  • 9am to noon36 (12%)
  • Noon to 3pm63 (22%)
  • 3pm to 6pm72 (25%)
  • 6pm to 9pm44 (15%)
  • 9pm to midnight33 (11%)

Collisions by month

  • January22 (7.6%)
  • February21 (7.3%)
  • March21 (7.3%)
  • April28 (9.7%)
  • May23 (8%)
  • June15 (5.2%)
  • July18 (6.2%)
  • August25 (8.7%)
  • September37 (13%)
  • October27 (9.3%)
  • November21 (7.3%)
  • December31 (11%)

Light conditions at the time

  • Daylight211 (73%)
  • Dark, no street lighting47 (16%)
  • Dark, street lights lit24 (8.3%)
  • Dark, lighting unknown7 (2.4%)

Source: Department for Transport, STATS19 road safety data

Road and weather conditions in B4366 crashes

On the B4366, 66% of collisions happened where the speed limit was 60 mph and 49% on a wet or damp road surface.

Speed limit at the scene

  • 20 mph2 (0.7%)
  • 30 mph79 (27%)
  • 40 mph1 (0.3%)
  • 60 mph191 (66%)
  • 70 mph16 (5.5%)

Weather at the time

  • Fine, no high winds185 (64%)
  • Raining, no high winds59 (20%)
  • Raining with high winds10 (3.5%)
  • Fine with high winds9 (3.1%)
  • Other23 (8%)
  • Not recorded3 (1%)

Road surface

  • Wet or damp143 (49%)
  • Dry139 (48%)
  • Snow3 (1%)
  • Flood over 3cm deep2 (0.7%)
  • Frost or ice2 (0.7%)

Type of road

  • Single carriageway282 (98%)
  • Roundabout4 (1.4%)
  • Dual carriageway2 (0.7%)
  • One way street or slip road1 (0.3%)

Source: Department for Transport, STATS19 road safety data

People hurt and vehicles involved in B4366 crashes

Car occupants make up 75% of the people killed or injured on the B4366, followed by pedestrians (8.9%).

Casualties by road user

  • Car occupant329 (75%)
  • Pedestrian39 (8.9%)
  • Motorcyclist33 (7.5%)
  • Bus or coach occupant9 (2.1%)
  • Cyclist9 (2.1%)
  • Van occupant7 (1.6%)
  • Taxi or private hire car occupant5 (1.1%)
  • Other8 (1.8%)

Vehicles involved

  • Car402 (78%)
  • Motorcycle32 (6.2%)
  • Van or goods vehicle up to 3.5 tonnes27 (5.3%)
  • Goods vehicle over 3.5 tonnes21 (4.1%)
  • Pedal cycle10 (1.9%)
  • Minibus6 (1.2%)
  • Other vehicle6 (1.2%)
  • Other9 (1.8%)

Casualties by age

  • 0 to 511 (2.5%)
  • 6 to 1018 (4.1%)
  • 11 to 1524 (5.5%)
  • 16 to 2088 (20%)
  • 21 to 2573 (17%)
  • 26 to 3585 (19%)
  • 36 to 4553 (12%)
  • 46 to 5540 (9.1%)
  • 56 to 6523 (5.2%)
  • 66 to 7516 (3.6%)
  • Over 758 (1.8%)

Drivers, passengers and pedestrians

  • Driver or rider274 (62%)
  • Passenger126 (29%)
  • Pedestrian39 (8.9%)

Source: Department for Transport, STATS19 road safety data

Map of recent crashes on the B4366

Map of the 25 most recent crashes on the B4366

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

  • 25 crashes
  • Serious
  • Slight

B4366 crashes by council area

Of the 289 collisions on the B4366, 288 were in Gwynedd.

Collisions on the B4366 in each area, 1979 to 2025
RankAreaCollisionsCasualtiesFatalSerious
1stGwynedd288438568

B4366 crashes by town

Of the 289 collisions on the B4366, 58 were in the built-up area of Caernarfon.

Recent crashes on the B4366

These are the 25 most recent collisions on the B4366, from 3 February 2008 to 19 November 2025.

Severity