The "IN" in PUFFIN can also stand for Infra Red as a reference to the I-R sensors. Not cameras of course.Crossings history:
Next, Puffin. P (Pedestrian) UFF (User-friendly) IN (Intelligent) (That's the crossing that is user-friendly and intelligent, not necessarily the user.)
These have infra-red cameras to monitor traffic and pedestrian movements.
If you push the button and walk away, it should cancel the request. In practice, these are in high pedestrian traffic areas, so other movement will keep it triggered.
If there is no traffic it should give traffic a red straight away. In busy times there will be a minimum delay to keep everyone moving.
If the traffic is approaching quickly, it should give a longer amber.
If the pedestrians walk slowly, it should give a longer green man signal.
(Note the use of should. Sometimes they can be observed working well.)
There is also an Equestrian crossing. Originally known as a Pegasus. This is a Puffin with wooden fences and higher call buttons for horse riders to use. They're a bit rare. Apparently there is one somewhere in London where the Police stable their horses, but I'm not sure a policeman on a horse needs the help of a traffic light. There is one on the A259 between Littlehampton and Worthing, but despite having passed through it about once a month for twelve years, I've never seen a horse rider using it.
Pegasus crossings can be found in Manchester city centre, although there's nothing to differentiate them from normal crossings linked to ATS apart from the second, higher push button and display.
The PELICAN was initially known as the PELICON crossing for PEdestrian Light CONtrolled.