I remember being particularly annoyed when the new curvey bridge over the Avon opened. The council up until then seemed to have favoured the split approach, for example the Bristol to Bath Cycle Path is clearly marked in two halves - one for cyclists, one for pedestrians which on the whole works well.
When the bridge was opened, they missed the opportunity to be consistant and up popped the Cyclists Dismount signs. The bridge was good and wide - plenty wide enough to allow a 50/50 split, but no they had to spoil it all with lazy signing - and of the course the irony is that dismounted cylists take up twice as much room width-wise and are on the bridge 'in the way' many times longer than they would be if they had stayed in the saddle... try explaining that to an angry commuter, though.
I did write to the council trying to make this point but received no answer.
Trouble is once the sign is up, everybodys' expectations are set - remain in the saddle and you are seen as a wrong 'un by everybody else, some cyclists included!
- bridge over Avon behind Temple Mead station