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Difficulty: HardPedestrian Crossings

You are driving towards a Puffin crossing on a multi-lane road. A pedestrian pushes the control button at the kerb but then crosses the road safely while traffic is clear before the light sequence changes. What will happen to the traffic signals as you approach?

  1. A
    The signal sequence will switch to a flashing amber phase, allowing drivers to proceed once they verify the crossing is clear.
  2. The infra-red and motion sensors will detect that the crossing area is empty and cancel the request, keeping the signal green for vehicles.Answer
  3. C
    The lights will change to red for a predetermined fixed duration, during which drivers may overtake stationary vehicles within the zig-zag area.
  4. D
    The signal will turn red, requiring you to come to a stop and flash your headlights to signal to oncoming vehicles that the crossing is clear.

Answer

The infra-red and motion sensors will detect that the crossing area is empty and cancel the request, keeping the signal green for vehicles.
Puffin crossings are equipped with electronic (infra-red and microwave) sensors that monitor the waiting area at the kerb and the crossing path. If someone pushes the button and then walks away or crosses while the road is clear, the system detects that the area is empty and automatically cancels the pedestrian demand, leaving the traffic light green so traffic is not delayed.

Step-by-Step Solution

1
Identify the crossing archetype and its operational technology.
The scenario specifies a Puffin crossing (Pedestrian User-Friendly Intelligent crossing), which employs kerbside detectors and on-crossing sensors rather than fixed timers.
Different crossing types (Pelican, Puffin, Toucan, Pegasus, Zebra) have distinct signal cycles and detection mechanisms under UK road regulations.
2
Analyze sensor response to pedestrian departure.
When the pedestrian leaves the waiting area before the traffic lights transition from green to red, the detectors recognize that no pedestrians are waiting or traversing the crossing.
The core function of Puffin crossing sensors is to optimize traffic flow by automatically cancelling redundant demands.
3
Determine the resulting signal status and correct driver expectation.
The crossing demand is cancelled, so the traffic lights remain steady green without unnecessary delay.
Vehicles are not brought to an unnecessary halt when no pedestrian requires safe passage.

Key Concept

Puffin crossing dynamic sensor operations and automated request cancellation
Estimated Time:1m 0s
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Topics

Pedestrian Crossings

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