Wrong signs at roadworks
> a) Why do so many contractors use 'cyclists dismount'?; and
They are confused and don't understand the law:
This is a the Code of Practice and failure to comply is an offence. Unfortunately the Enforcement Authority - the Highway Authority is also, on occasion, a transgressor.
Page 51 (59/82 in the PDF) has the main piece of text that applies. You'll see that 'Cyclists Dismount....' is mentioned but only in the context of when the carriageway is closed but the footway remains open.
> b) What can we do about it?
Every time you come across this, give the Highways people a ring and make a complaint. Ask for an incident number and follow up the following day. Perhaps cyclists can aggregate reports and, if it turns out the Highway Authority isn't doing their job, make a complaint to the Ombudsman.