What is the ideal intersection according to Sustainable Safety?

Answer

According to Sustainable Safety, the ideal intersection depends on the road categories of the intersecting roads. For more information about Sustainable Safety, see SWOV fact sheet Sustainable Road Safety. Table 3 indicates which intersection is recommended at which location. The recommended intersections are presented in order of safety, from most recommended to least recommended. An additional note: At 50-50/50-70/70-70 (distributor-distributor road) intersections, safety depends on the capacity of the intersection. Intersection capacity in its turn depends on the number of lanes on the legs and the traffic distribution across the legs. The table is based on the assumption that each intersection has the same traffic volume. However, because a priority intersection has a lower capacity, it cannot cope well with a large amount of traffic when demand is high. For busy intersections, a signalised priority intersection is therefore safer. The section under the question Which intersection types are safest? explains why one intersection type is safer than the other.

Table 3. Recommended intersection types. The safest and therefore preferred type is mentioned first.*In the figure GOW stand for distributor road and ETW for access road.

The guiding principle for sustainably safe intersections is that conflicts between vehicles may and can only occur when vehicle speed and mass do not strongly diverge [9]. For the sake of road safety, traffic calming measures near or on intersections are therefore required. At intersections with distributor roads in the urban area, where motorised traffic meets, a maximum speed of 50 km/h is considered safe. In situations where heavy motorised traffic intersects with the much lighter (light) mopeds and bicycles or with pedestrians, speed should be reduced even more. For example, for intersections with distributor roads in the urban area where pedestrians and cyclists intersect with motorised traffic, the safe maximum speed is 30km/h [9]. Lower speeds can be enforced by roundabouts, speed humps just before the intersection, or a raised junction. In addition, sustainably safe intersection requirements are intended to exclude certain combinations of crash opponents (for example trucks and bicycles) being involved in conflicts in certain circumstances, since the implemented traffic facility virtually excludes these encounters [9]. For the purpose of sustainable safety, the following intersection facilities are therefore recommended (Table 4):

 

Conflict

Conflict or crash opponent

Motor vehicles with each other

Pedestrians, bicycles and mopeds with each other

Cars or trucks versus pedestrian, bicycle or moped

Converging or diverging conflicts

Roundabout

-

Paths/tracks and 50km/h roads: deflection of the bicycle track

At traffic lights: bike box

Lateral conflicts

Roundabout or speed hump

Speed hump

Roundabout or speed hump

Frontal conflicts, with turns

Dedicated turning lane for left turns (not at roundabouts)

-

Median

Table 4. Main intersection facilities to prevent common conflicts or collisions. For a more detailed description of the conflict types, see the section What characteristics affect intersection safety? And for information on deflection of the bicycle track and the bike box, see the section How to make intersections safer for cyclists?.

In practice, the choice of facility often depends on aspects other than road safety. For example, traffic volume, available space and costs.
Part of fact sheet

Roundabouts and other intersections

About one third of the road deaths on Dutch roads occur at intersections. Within the urban area, this amounts to half and outside the urban area to Meer

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