Ray, Regulation 37 of the CDM Regulations is probably applicable: driver to ensure that they warn others working in the vicinity of vehicles. PH2

Thanks guys, I was hoping for something more explicit to do with 'flashing amber lights' but I guess it does not exist having trawled through a number of different HSE documents. Clever them [reference removed]...

If by 'requirement for' you mean the performance of the light, rather than whether it needs a light or not, it is probably the case that the beacons on plant meet the requirements of the beacons for slow-moving vehicles on highways, in which case the actual performance specification for them will be as the The Road Vehicles Lighting Regulations, specifically Regulation 17 and Schedule 16: Regulation 17: no person shall use, or cause or permit to be used, on an unrestricted dual-carriageway road any motor vehicle with four or more wheels having a maximum speed not exceeding 25 mph unless it or any trailer drawn by it is fitted with at least one warning beacon which– (a)complies with Schedule 16, and (b)is showing an amber light. Schedule 16: 1. Number: Sufficient to satisfy the requirements of paragraph 3 2. Position: Every warning beacon shall be so mounted on the vehicle that the centre of the lamp is at a height not less than 1200 mm above the ground. 3. Angles of visibility: The light shown from at least one beacon (but not necessarily the same beacon) shall be visible from any point at a reasonable distance from the vehicle or any trailer being drawn by it. ... 11. Other requirements: The light shown by any one warning beacon shall be displayed not less than 60 nor more than 240 equal times per minute and the intervals between each display of light shall be constant.

Ray - the 2nd bottom paragraph here might be what you are looking for? http://www.hse.gov.uk/pubns/indg199.pdf David

Thanks David et al, still all a bit vague for my colleague who asked the question "is it compulsory for plant to have and use flashing lights on a construction site?" Incidentally, my previous comment at #4 was deleted by the spell checker [reference removed]...but was not a derogatory or obscene comment - strange! As it is Friday I am going to see if I can beat it...HSE P-e-o-p-l-e.