I was looking at CAP 642 today and came across a part relating to the operation of jetbridges, which reminded me of this post. The documents states:
It is suggested that the following auxiliary equipment is fitted to apron drive airbridges:
(a) Audible and visual alarms that operate automatically when the bridge is in motion.
(b) In order to overcome downward and rearward blindspots for the operator, CCTV or sight mirrors to cover blind areas.
(c) Pressure sensitive safety hoops which, when they touch an object, cut out the motive force thus stopping movement of the bridge.
You can view the document in pdf format at http://www.caa.co.uk/docs/33/CAP642.pdf - Section 5, part 2.4
I think the key point is that these are all "suggested" but not required.