DCAN 15: Vehicular Access Standards
Table A: X-distance (m)
|Type of Access||X-distance|
|Access with traffic flow up to 60 vpd||The minimum x-distance is normally 2.4m. Where traffic speeds on the priority road are below 60 kph (37mph), the minimum x- distance is 2.0m. On other roads the x-distance may be reduced to 2.0m only where danger is unlikely to be caused|
|Access with traffic flow 60 & 1000 vpd||The minimum x-distance is normally 4.5m. It may be reduced to 2.4m, but only if traffic speeds on the priority road are below 60 kph (37mph) and danger is unlikely to be caused.|
|Access with traffic flow over 1000 vpd||The desirable minimum x-distance is 6.0m. It may be reduced to 4.5m, but only where danger is unlikely to be caused. In this case developers may be required to demonstrate the adequacy of the access capacity using junction analysis techniques|
- Reductions in visibility standards will not be permitted simply because the applicant does not control the required visibility area or does not have a reasonable prospect of bringing it under his control.
- Traffic volumes are in vehicles per day (vpd) and refer to the total combined flow in both directions. Volumes on the priority road include traffic generated by the development.
- If there is a dispute about the predicted minor road (access) traffic flow, it shall be determined by reference to a recognised database such as TRICS 3, or failing that by a direct survey of a similar existing development over an acceptable period.
- Where the minor road (access) flow is subject to peaks, an enhanced x-distance may be required.
- The traffic speed to be used is a reasonable estimate of the 85%ile speed on the priority road; for example, by the use of following vehicle surveys or, in the case of a dispute, the measured 85%ile speed.