Cycle detection

Specific cycle detection at signalised intersections is required when the following criteria are met:

an intersection movement used by people on bikes is called on demand only (this movement may commence from a general traffic lane, or from a facility for the specific use by people on bikes), or
at wide intersections, an all-red phase extension is required for cyclists to safely finish crossing the intersection.

Cycle detection can be provided in various forms including:

inductive loops at the stop line (in the cycle facility/space, or in the general traffic lane)
inductive loops before the stop line (providing time to switch to a green cycle phase) – these are only appropriate where cyclists are unlikely to turn off before the intersection/crossing
push-button detectors
other detection types exist (eg microwave) but are not commonly used in New Zealand as of 2016.

The table below presents key considerations when designing inductive loops for cyclists.

Table: Key considerations for cycle detection

Detection type	Key considerations
General stop line loops in traffic lane	May not detect cyclists where their path does not pass over loop. Most loops do not distinguish cyclists from general traffic, but some loops have the ability to do so. Need to be placed so that they are being ridden over by cyclists by default.
Separate stop line loops for cyclists	Must be provided where detection criteria are. Best practice is to mark the most sensitive area using diamond symbols and small cycle symbols. Austroads GTM part 9 recommends loops spanning the entire width of the facility. Could use cycle-specific loops. These are shaped and laid out to detect cyclists with the highest accuracy. Where separate cycle loops are provided the gathering of cycle count data should also be considered where practicable. Some of those loops can reliably detect bicycles in mixed traffic. Where loops are used on a cycle path or for a cycle crossing, a modified pedestrian call button can be incorporated that lights up to show when a bicycle has been detected. Detection of bicycles can also be used to activate a sign to alert drivers to the presence of cyclists, such as narrow bridges, tunnels, or areas with limited forward visibility. (See case study: Appleby bridge activated warning sign, Nelson.)
Bicycle detection located before the stopline	These may only be appropriate where cyclists will not turn off before the intersection or crossing. Could use cycle-specific loops. These are shaped and laid out to detect cyclists with the highest accuracy.

Note that it is rarely necessary to detect cyclists in a hook turn box, but those cases do exist, for example if the cyclist movement is not required by motorised traffic and therefore it is necessary to know when cyclists are present to call the movement. Also note that consideration was given by a New Zealand RCA to terminate a left turning movement supported by a green arrow that conflicted with straight through cyclists during a full green signal if cyclists were detected, but it was decided that detection of bicycles is not reliable enough, and other measures need to be considered to resolve the conflict.

Inductive loops can be set to detect the passage of a vehicle, or its presence. If presence detection is chosen, the loops need to be located where a vehicle would stop. If passage detection is used, the loop can be placed anywhere on the approach where the vehicle would pass it, including at the limit line.

Information on the use of induction loops for cyclists at wide intersections (all-red extension) is available in ‘Cyclists at Wide Intersections, All-Red Time Extension on Demand’(external link).

Detailed design information on push button detection will be provided in the National Traffic Signal Specification which is currently being prepared.

Handrails should be considered adjacent to the cyclist waiting area where practicable. The installation of foot rails below handrails, adjacent to push buttons, should also be considered where no kerb is present.

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