Charges for CPZ are doubling to £120pa (up from £30 when St Davids CPZ was introduced).

The argument against a Herne Hill style CPZ is that St Davids was too small and that they would not make enough money from fines and permits to cover the running costs. Maybe having the four/five zones michael suggested would mean that there was a large enough area covered by CPZ to enable this solution to be reconsidered.

As to the initial costs being high, there a Ticket machines to install, signs to erect and the road to mark, as well as the costs of consultations. Ongoing costs include servicing of ticket machines and enforcement action / helpdesk. Any profit is supposedly ploughed back into road repairs, although I'm sure NSL take a good chunk.