Junction Assessments

Junction assessments require evaluation of characteristics of junctions.

This may encompass:

Visibility assessment
Swept path analysis
Traffic capacity evaluation

In order for priority junctions to operate safely, vehicles entering the junction from minor arms (those which have to give way to approaching traffic) need to have sufficient visibility along the approaching road, to see vehicles travelling towards the junction.

Visibility requirements are dependant on the speed of approaching traffic. For obvious reasons, vehicles approaching at high speed would take longer to react to a vehicle emerging into the junction. Similarly, if traffic is likely to be approaching the junction at high speed, a 'safe gap' to emerge into the junction woud be longer for high speed traffic, than for low speed traffic.

The swept path of vehicles may need to be tested for junctions or roadways which are limited in terms of width or turning angles required. Common examples are requirements to check that refuse vehicles or emergency vehicles can access a development safely and easily, without the need for excess manouvering. Swept path analysis takes into account the track of the vehicle wheels and the swept path of any overhanging parts of the vehicle.

Traffic capacity evaluation may be as simple as considering the balance of traffic volumes on each arm of the junction. Where the traffic on the major arms of the junction is high, there may be limited capacity available to traffic which needs to enter the junction from the minor arm(s). if capacity is limited, a junction model may need to be developed, using proprietary junction modelling software.