Only crashes which occur at or within 20 metres of a junction are coded by Junction Detail. If two or more junctions are present within 20 metres, the junction closest to the to the crash location is used.
The following definitions apply to particular varieties of junction:
- T junction includes 3 arm junctions where 2 roads join at an acute angle (sometimes known as 'Y' junctions).
- Crossroads refers to four arm junctions where the alignment of both roads is uninterrupted whatever the angle of the crossing, and the arms are not staggered.
- Multiple junction refers to all junctions with more than four arms, except roundabouts.
Slip roads which lie within 20 metres of a roundabout are considered to be part of the roundabout for the purposes of junction detail. Also, crashes on slip roads over 20 metres from a junction are not considered to be at the junction. Therefore, only crashes occurring within 20 metres of the point where a slip road merges with or diverges from the nearside of the main carriageway are classified as slip road junctions.