Fatal
Serious
Slight
Uncategorised
| Date | Local Authority | Vehicles | Casualties | Severity |
|---|---|---|---|---|
| Sat 4 Jan 1986 | Barnet | 2 | 1 | Slight |
| Sun 5 Jan 1986 | Hertsmere | 1 | 2 | Serious |
| Tue 7 Jan 1986 | Hertsmere | 1 | 1 | Slight |
| Fri 10 Jan 1986 | Barnet | 3 | 1 | Slight |
| Sat 11 Jan 1986 | Watford | 2 | 1 | Serious |
| Sun 12 Jan 1986 | Barnet | 2 | 1 | Slight |
| Mon 13 Jan 1986 | Hertsmere | 2 | 1 | Slight |
| Mon 13 Jan 1986 | Watford | 1 | 1 | Slight |
| Tue 14 Jan 1986 | Hertsmere | 1 | 1 | Slight |
| Wed 15 Jan 1986 | Barnet | 1 | 1 | Slight |
| Thu 16 Jan 1986 | Three Rivers | 2 | 1 | Slight |
| Fri 17 Jan 1986 | Three Rivers | 2 | 1 | Slight |
| Fri 17 Jan 1986 | Hertsmere | 2 | 1 | Slight |
| Fri 17 Jan 1986 | Barnet | 1 | 1 | Slight |
| Sat 18 Jan 1986 | Watford | 2 | 1 | Slight |
| Tue 21 Jan 1986 | Barnet | 1 | 1 | Slight |
| Thu 23 Jan 1986 | Three Rivers | 2 | 2 | Slight |
| Thu 23 Jan 1986 | Watford | 2 | 1 | Slight |
| Fri 24 Jan 1986 | Watford | 2 | 1 | Slight |
| Sun 26 Jan 1986 | Watford | 2 | 1 | Slight |
| Mon 3 Feb 1986 | Barnet | 2 | 2 | Slight |
| Wed 5 Feb 1986 | Three Rivers | 4 | 1 | Slight |
| Wed 5 Feb 1986 | Barnet | 4 | 1 | Slight |
| Wed 5 Feb 1986 | Barnet | 4 | 1 | Slight |
| Thu 13 Feb 1986 | Barnet | 1 | 1 | Slight |
| Mon 17 Feb 1986 | Watford | 1 | 1 | Slight |
| Wed 26 Feb 1986 | Hertsmere | 2 | 1 | Slight |
| Thu 27 Feb 1986 | Three Rivers | 2 | 1 | Slight |
| Fri 28 Feb 1986 | Hertsmere | 1 | 1 | Slight |
| Sat 1 Mar 1986 | Hertsmere | 1 | 2 | Serious |
| Tue 4 Mar 1986 | Hertsmere | 1 | 1 | Slight |
| Wed 5 Mar 1986 | Hertsmere | 1 | 1 | Serious |
| Thu 6 Mar 1986 | Watford | 2 | 4 | Slight |
| Fri 7 Mar 1986 | Hertsmere | 1 | 1 | Slight |
| Tue 11 Mar 1986 | Watford | 4 | 3 | Slight |
| Fri 14 Mar 1986 | Three Rivers | 4 | 1 | Slight |
| Fri 14 Mar 1986 | Barnet | 2 | 1 | Slight |
| Tue 18 Mar 1986 | Barnet | 1 | 1 | Slight |
| Wed 19 Mar 1986 | Barnet | 1 | 1 | Slight |
| Tue 25 Mar 1986 | Watford | 2 | 1 | Slight |
| Wed 26 Mar 1986 | Watford | 3 | 1 | Slight |
| Wed 26 Mar 1986 | Watford | 3 | 1 | Slight |
| Thu 27 Mar 1986 | Hertsmere | 2 | 1 | Serious |
| Sat 5 Apr 1986 | Hertsmere | 3 | 2 | Slight |
| Wed 9 Apr 1986 | Watford | 2 | 1 | Serious |
| Wed 9 Apr 1986 | Barnet | 2 | 1 | Serious |
| Sat 12 Apr 1986 | Watford | 3 | 1 | Slight |
| Mon 14 Apr 1986 | Watford | 1 | 1 | Slight |
| Fri 18 Apr 1986 | Three Rivers | 2 | 1 | Slight |
| Sat 19 Apr 1986 | Watford | 2 | 1 | Slight |
| Tue 22 Apr 1986 | Barnet | 2 | 1 | Slight |
| Fri 25 Apr 1986 | Barnet | 1 | 1 | Slight |
| Sat 3 May 1986 | Watford | 1 | 3 | Serious |
| Mon 5 May 1986 | Hertsmere | 2 | 1 | Serious |
| Fri 9 May 1986 | Hertsmere | 1 | 1 | Slight |
| Fri 9 May 1986 | Barnet | 2 | 2 | Slight |
| Mon 12 May 1986 | Hertsmere | 2 | 1 | Serious |
| Mon 12 May 1986 | Barnet | 2 | 2 | Slight |
| Wed 14 May 1986 | Watford | 1 | 1 | Slight |
| Wed 14 May 1986 | Watford | 1 | 1 | Slight |
| Thu 15 May 1986 | Barnet | 2 | 1 | Slight |
| Fri 16 May 1986 | Barnet | 2 | 1 | Slight |
| Tue 20 May 1986 | Hertsmere | 2 | 1 | Slight |
| Tue 20 May 1986 | Hertsmere | 3 | 2 | Serious |
| Tue 20 May 1986 | Barnet | 2 | 1 | Slight |
| Tue 20 May 1986 | Watford | 2 | 1 | Slight |
| Thu 22 May 1986 | Watford | 3 | 1 | Slight |
| Fri 23 May 1986 | Barnet | 4 | 1 | Slight |
| Fri 23 May 1986 | Watford | 3 | 1 | Slight |
| Wed 28 May 1986 | Watford | 2 | 1 | Serious |
| Thu 29 May 1986 | Three Rivers | 2 | 1 | Slight |
| Sun 1 Jun 1986 | Watford | 2 | 2 | Slight |
| Thu 5 Jun 1986 | Hertsmere | 1 | 1 | Slight |
| Fri 6 Jun 1986 | Hertsmere | 2 | 1 | Serious |
| Fri 6 Jun 1986 | Three Rivers | 2 | 2 | Slight |
| Fri 6 Jun 1986 | Barnet | 2 | 1 | Slight |
| Sat 7 Jun 1986 | Watford | 1 | 1 | Slight |
| Sun 8 Jun 1986 | Watford | 1 | 1 | Slight |
| Mon 9 Jun 1986 | Watford | 1 | 1 | Slight |
| Mon 9 Jun 1986 | Watford | 1 | 1 | Slight |
| Tue 10 Jun 1986 | Hertsmere | 3 | 1 | Serious |
| Fri 13 Jun 1986 | Watford | 1 | 1 | Slight |
| Fri 13 Jun 1986 | Hertsmere | 2 | 1 | Slight |
| Tue 17 Jun 1986 | Hertsmere | 2 | 2 | Slight |
| Thu 26 Jun 1986 | Watford | 2 | 1 | Serious |
| Thu 26 Jun 1986 | Barnet | 2 | 1 | Slight |
| Sat 28 Jun 1986 | Watford | 2 | 1 | Serious |
| Sun 29 Jun 1986 | Hertsmere | 2 | 1 | Slight |
| Mon 30 Jun 1986 | Watford | 1 | 1 | Slight |
| Tue 1 Jul 1986 | Watford | 2 | 1 | Slight |
| Fri 4 Jul 1986 | Barnet | 2 | 1 | Slight |
| Sat 5 Jul 1986 | Watford | 1 | 1 | Serious |
| Sat 5 Jul 1986 | Hertsmere | 2 | 4 | Slight |
| Sun 6 Jul 1986 | Barnet | 1 | 1 | Slight |
| Tue 8 Jul 1986 | Watford | 1 | 2 | Serious |
| Wed 9 Jul 1986 | Watford | 1 | 1 | Slight |
| Thu 10 Jul 1986 | Watford | 3 | 1 | Slight |
| Sat 12 Jul 1986 | Watford | 1 | 1 | Slight |
| Mon 14 Jul 1986 | Three Rivers | 2 | 1 | Serious |
| Tue 15 Jul 1986 | Watford | 2 | 1 | Slight |
| Tue 15 Jul 1986 | Hertsmere | 2 | 2 | Slight |
| Mon 28 Jul 1986 | Barnet | 2 | 1 | Slight |
| Wed 30 Jul 1986 | Watford | 2 | 1 | Serious |
| Thu 31 Jul 1986 | Barnet | 2 | 1 | Slight |
| Fri 1 Aug 1986 | Hertsmere | 2 | 1 | Slight |
| Fri 1 Aug 1986 | Watford | 1 | 1 | Slight |
| Fri 1 Aug 1986 | Barnet | 1 | 1 | Slight |
| Fri 1 Aug 1986 | Barnet | 2 | 1 | Slight |
| Sun 3 Aug 1986 | Barnet | 2 | 1 | Slight |
| Sun 3 Aug 1986 | Barnet | 1 | 2 | Serious |
| Mon 4 Aug 1986 | Hertsmere | 1 | 1 | Slight |
| Wed 6 Aug 1986 | Hertsmere | 2 | 1 | Slight |
| Thu 7 Aug 1986 | Barnet | 2 | 1 | Slight |
| Thu 7 Aug 1986 | Watford | 2 | 1 | Slight |
| Fri 8 Aug 1986 | Watford | 2 | 3 | Slight |
| Sat 9 Aug 1986 | Watford | 2 | 2 | Slight |
| Sat 9 Aug 1986 | Watford | 2 | 2 | Slight |
| Thu 14 Aug 1986 | Watford | 2 | 1 | Slight |
| Sat 16 Aug 1986 | Barnet | 2 | 1 | Slight |
| Fri 22 Aug 1986 | Hertsmere | 2 | 1 | Slight |
| Mon 25 Aug 1986 | Hertsmere | 2 | 1 | Slight |
| Sun 31 Aug 1986 | Barnet | 2 | 1 | Slight |
| Fri 5 Sep 1986 | Barnet | 2 | 1 | Slight |
| Sun 7 Sep 1986 | Hertsmere | 2 | 1 | Slight |
| Sun 7 Sep 1986 | Barnet | 2 | 1 | Slight |
| Tue 9 Sep 1986 | Watford | 2 | 1 | Slight |
| Thu 11 Sep 1986 | Hertsmere | 2 | 2 | Slight |
| Sat 13 Sep 1986 | Hertsmere | 1 | 1 | Slight |
| Fri 19 Sep 1986 | Watford | 1 | 1 | Serious |
| Sat 20 Sep 1986 | Hertsmere | 2 | 1 | Slight |
| Tue 23 Sep 1986 | Hertsmere | 2 | 1 | Slight |
| Thu 25 Sep 1986 | Watford | 2 | 1 | Slight |
| Thu 25 Sep 1986 | Watford | 2 | 1 | Slight |
| Sat 27 Sep 1986 | Watford | 2 | 2 | Serious |
| Mon 29 Sep 1986 | Hertsmere | 2 | 1 | Slight |
| Wed 1 Oct 1986 | Barnet | 2 | 1 | Slight |
| Thu 2 Oct 1986 | Watford | 2 | 1 | Slight |
| Thu 2 Oct 1986 | Barnet | 2 | 1 | Slight |
| Thu 2 Oct 1986 | Barnet | 2 | 1 | Slight |
| Thu 9 Oct 1986 | Watford | 1 | 1 | Slight |
| Thu 9 Oct 1986 | Watford | 1 | 1 | Slight |
| Thu 9 Oct 1986 | Hertsmere | 2 | 1 | Slight |
| Fri 10 Oct 1986 | Watford | 3 | 1 | Slight |
| Sat 11 Oct 1986 | Barnet | 2 | 3 | Serious |
| Sat 11 Oct 1986 | Watford | 1 | 1 | Slight |
| Tue 14 Oct 1986 | Hertsmere | 1 | 1 | Slight |
| Tue 14 Oct 1986 | Hertsmere | 2 | 1 | Serious |
| Tue 21 Oct 1986 | Watford | 2 | 2 | Serious |
| Fri 24 Oct 1986 | Hertsmere | 2 | 2 | Slight |
| Tue 28 Oct 1986 | Hertsmere | 2 | 1 | Slight |
| Thu 30 Oct 1986 | Barnet | 2 | 1 | Slight |
| Thu 30 Oct 1986 | Barnet | 4 | 1 | Serious |
| Fri 31 Oct 1986 | Watford | 2 | 2 | Slight |
| Mon 3 Nov 1986 | Hertsmere | 2 | 2 | Serious |
| Tue 4 Nov 1986 | Hertsmere | 2 | 1 | Slight |
| Tue 4 Nov 1986 | Watford | 1 | 1 | Slight |
| Wed 5 Nov 1986 | Hertsmere | 1 | 1 | Slight |
| Wed 5 Nov 1986 | Watford | 3 | 5 | Slight |
| Mon 10 Nov 1986 | Hertsmere | 2 | 1 | Slight |
| Thu 13 Nov 1986 | Hertsmere | 1 | 1 | Slight |
| Sun 16 Nov 1986 | Watford | 2 | 4 | Serious |
| Sun 16 Nov 1986 | Hertsmere | 2 | 1 | Serious |
| Tue 18 Nov 1986 | Barnet | 2 | 1 | Slight |
| Thu 20 Nov 1986 | Watford | 2 | 1 | Slight |
| Fri 21 Nov 1986 | Hertsmere | 2 | 3 | Slight |
| Sun 23 Nov 1986 | Barnet | 2 | 2 | Slight |
| Wed 26 Nov 1986 | Watford | 1 | 1 | Serious |
| Thu 27 Nov 1986 | Barnet | 1 | 1 | Slight |
| Thu 27 Nov 1986 | Barnet | 1 | 1 | Slight |
| Sat 29 Nov 1986 | Hertsmere | 2 | 2 | Slight |
| Sun 30 Nov 1986 | Hertsmere | 2 | 2 | Slight |
| Sun 30 Nov 1986 | Hertsmere | 2 | 1 | Slight |
| Thu 4 Dec 1986 | Watford | 2 | 1 | Slight |
| Thu 4 Dec 1986 | Watford | 2 | 1 | Serious |
| Sat 6 Dec 1986 | Barnet | 1 | 1 | Slight |
| Sat 6 Dec 1986 | Watford | 1 | 1 | Slight |
| Mon 8 Dec 1986 | Hertsmere | 1 | 1 | Fatal |
| Tue 9 Dec 1986 | Watford | 1 | 2 | Slight |
| Tue 9 Dec 1986 | Watford | 1 | 2 | Slight |
| Tue 9 Dec 1986 | Watford | 2 | 1 | Slight |
| Thu 11 Dec 1986 | Watford | 2 | 1 | Slight |
| Mon 15 Dec 1986 | Barnet | 4 | 2 | Slight |
| Mon 15 Dec 1986 | Hertsmere | 2 | 1 | Slight |
| Fri 19 Dec 1986 | Barnet | 2 | 5 | Slight |
| Fri 19 Dec 1986 | Barnet | 2 | 1 | Slight |
| Mon 22 Dec 1986 | Watford | 3 | 3 | Serious |
| Mon 22 Dec 1986 | Watford | 3 | 3 | Serious |
| Sun 28 Dec 1986 | Hertsmere | 2 | 3 | Slight |