Mobility and Transport

Clean transport, Urban transport

1.5 Intersections

1.5 Intersections

Overview

Intersections are points on a road network when road users cross paths. Examples include junctions, roundabouts, driveways and the end of cycle routes. Intersections can also include crossing points involving pedestrians.

The quality and number of intersections along a cycleway can limit its attractiveness as they increase cyclists' waiting times. Ensuring that intersections are designed well is also important from the perspective of safety, as the majority of road accidents occur at intersections. Therefore, it is very important that the appropriate intersection solution is selected and that the design follows best practice.

Finance

The finance required will depend on the size and complexity of the intersection. Costs will increase significantly whenever a carriageway needs altering; upgrading an existing crossing may not necessarily cost less than building a new one. In the UK's Cycle City Ambition project, remodelled major junctions have cost between €0.3 million and €1.8 million, while cycle crossings at major roads have cost between €0.3 million and €0.5 million [1]. The institute for road safety research in the Netherlands (SWOV), estimates that the costs of converting an intersection into a single-lane roundabout are approximately €400,000 (Wijnen et al., 2010).

Infrastructure quality design guidance

The traffic intensity, speed and number of traffic lanes should guide the choice of the most appropriate intersection design. At any intersection, there will be conflict points between transport modes, but effective intersection design can reduce possible conflicts and increase safety and comfort for cyclists. Good design will generally include the following principles:

  • Avoid mixing motor traffic with cyclists where the traffic flow and/or speed is typically high.
    • On carriageways with low traffic volumes and low traffic speeds, cyclists usually mix with other road traffic and cycling specific infrastructure is not necessary at intersections (SUTP, Fact Sheet H-04).
  • Maximise separation of cyclists from dangerous traffic movements
    • Separate traffic light phases for people cycling and people motoring or separate routes by over/underpasses
  • Maximise the visibility of cyclists.
    • Make drivers aware of cyclists on the approach to an intersection. Using bike boxes and advanced green lights can allow cyclists to proceed through an intersection ahead of other road traffic.
  • Cyclists should be given priority at intersections.
    • This requires specific design to underline the priority status of cyclists. The PRESTO 'Right-Of-Way Intersections' factsheet explores the design options in more detail. The figure below shows an example of an advanced green signal for cyclists at an intersection.
  • Intersections should be easy to identify, understand, and use by all transport modes.
    • Coloured surfaces can improve the coherence of an intersection and increase drivers' awareness of cyclists.

Advanced green signal for cyclists, Superhighways The Capital Region of Denmark

The Urban Bikeway Design Guide (NACTO, 2014) and Handbook for cycle-friendly design (SUSTRANS, 2014) include descriptions of a number of intersection features, including bike boxes, intersection crossing markings, two-stage bicycle turn box, refuge islands, through bike lanes to position cyclists on the correct side of turning traffic, and mixing zones that advise road users of proper positioning within the lane. They also consider several designs for cycle tracks approaching an intersection.

City practitioners should consult national cycle infrastructure design standards or regulations (where available) regarding the appropriate implementation of intersections in respective Member States.

Considerations for different types of intersection

Right-of-way intersections are the simplest intersection solution on roads with low traffic intensities, while signalised intersections are recommended when a cycling route crosses a main road with high traffic volumes and particularly if there are multiple lanes. Roundabouts are considered to be a safer alternative to signalised intersections, although they cannot handle as many vehicles. When a cycle route crosses a main road with traffic volumes over 1,500 passenger car units per hour, a grade-separated crossing ( 1.4 Grade-separated crossings) is recommended (PRESTO, Roundabout Intersections). Several crossing types are available when a cycle track crosses a carriageway, presented in the ‘cycle track crossings’ sections below.

Right-of-way intersections

A right-of-way intersection is used to give one road priority over another, without signalisation. It is the simplest intersection solution for cyclists on roads with low traffic intensities. The right of way can follow the priority-from-the-right/left approach or be controlled through signage and road markings.

An important safety consideration at intersections is the visibility of cyclists. In situations where cyclists and motor traffic are approaching the intersection in close vicinity (i.e. cycle lanes or mixed traffic), it is assumed that drivers are aware of cyclists. However, in situations where cyclists are separated from the carriageway, it is advised that the cycle path should be designed alongside the carriageway on the approach to the intersection to increase drivers' awareness of cyclists (FGSV, 2010).

The SUTP factsheet on intersections provides specific recommendations for cyclists turning across traffic and situations where the speed of motorists should be reduced (SUTP, Fact Sheet H-04).

Signalised intersections (traffic lights)

Priority design for cyclists can improve their safety. For example, advanced stop lines (bike boxes) and separate green lights for cyclists can allow them to proceed through the intersection ahead of other road traffic. A feeder cycle lane is recommended to allow cyclists to proceed past waiting traffic and up to the advanced stop line (PRESTO, Traffic-Light Intersections). The Urban Bikeway Design Guide (NACTO, 2014) provides detailed guidance on bike boxes. Cycle-friendly design can also include a dedicated turning lane for cyclists, which may bypass the red light (SUTP, Fact Sheet H-04).

Roundabouts

Roundabouts are recommended when a cycle route crosses a moderately busy road, although it must be considered that they considerably slow down buses and they are not pedestrian friendly.

Single lane roundabouts are considered the safest intersection design for all users on moderately busy roads. They reduce the speed of approaching traffic and allow the smooth flow of traffic through the intersection. Two-lane roundabouts are particularly dangerous for cyclists due to the movement of motor traffic between lanes. The figure below highlights three possible conflict points between cyclists and motorised traffic on any roundabout.

Benoît Dupriez et Miguel Vertriest, 2009:  Aménagements cyclables en giratoires - As in Presto

The PRESTO roundabout Intersections factsheet defines in detail the situations when a roundabout should be considered. The Sustrans Handbook for cycle-friendly design also graphically displays a number of design recommendations for roundabouts.

Grade separated crossings

Tunnels and bridges can be implemented to facilitate the crossing of natural barriers (e.g. rivers), railway tracks and busy roads. They improve directness and increase safety by reducing the interaction between cyclists and motor traffic. However, grade separated crossings are expensive and require significant time and human resources time to implement. See the 1.4 Grade-separated crossings measure page for more information.

Cycle track crossings

When 1.2 Cycle tracks cross a road, there are a number of crossing types available, dependent on the traffic speed and level of the flow. Busier cycle routes will also justify a crossing type that gives cyclists greater priority. 

Footnotes

[1]  Taylor I and Hiblin B (2017), Typical Costs of Cycling Interventions: Interim analysis of Cycle City Ambition schemes  PDF icontypical_costs_of_cycling_interventions_interim_analysis_of_cycle_city_ambition_scheme