A puffin crossing (its name derived from the phrase "pedestrian user-friendly intelligent") is a type of pedestrian crossing in use in the United Kingdom. The design is distinct from the older pelican crossing in that the lights signalling to the pedestrians are on the same side of the road as the pedestrian, rather than across the road. From 2016, pelican crossings began to be phased out in the United Kingdom, to be replaced with puffin crossings. They have two sensors on top of the traffic lights (PCD – pedestrian crossing detector, and PKD – pedestrian kerb detector). These sensors detect if pedestrians are crossing slowly and can hold the red traffic light longer if needed. If a pedestrian presses the button but then walks off, the PKD will cancel the request making the lights more efficient. Function Unlike the older pelican crossing designs, where the pedestrian signal lights are mounted on the opposite side of the road, the puffin crossing has them mounted at the near road side, set diagonally to the road edge. This allows the pedestrian to monitor passing traffic while waiting for the signal to cross. A second reason for the design is that having the lights closer to the user assists visually impaired people who could have difficulty viewing the signal from across the carriageway. Some push-button units (the lower box in the image) are also fitted with a tactile knob under the unit which rotates when the user may cross. This feature is to assist visually impaired people who struggle to see the light change. After a request to cross (by button press), a kerb side detector monitors the pedestrian's presence at the crossing. Should the pedestrian cross prematurely, walk away from the crossing, or wait outside the detection area, the pedestrian's request to cross could be automatically cancelled. This is so traffic is not halted unnecessarily. An on-crossing detector ensures that the signal for vehicles remains red until pedestrians have finished crossing (within practical limits). Unlike the pelican crossing, there is no transitional "flashing" phase. The pedestrian phase will start at the moment all three of these conditions are fulfilled: the pedestrian push button has been pressed since the end of the last pedestrian phase the "Maximum Traffic Green Timer" has expired the detectors indicate that a pedestrian is still waiting to cross The "Maximum Traffic Green Timer" is started either when the pedestrian