If I thought scrapping the extension was going to worsen road conditions I'd be dead against it, but as it is, the Congestion Charge never actually reduced congestion did it?
I think initially it did reduce traffic coming into the capital, however after a short time car users realised they hated using public transport and drifted back to using thier cars and accepted the resulting charges. Make it £200 a day and it might actually work.
The CC reduced motor traffic considerably when it first started. Later, however, the charge did not keep pace with inflation and businesses passed the cost on to their customers, among other factors.
It is a blunt instrument that needs a lot of TLC to keep it working.
The WECCZ had a number of systematic mistakes built into it that should have been addressed:
(1) One rate for both zones--should have been separate rates;
(2) No difference in rate for the two zones--should have been a higher, separate rate for the inner zone;
(3) It should have been conceived as the first segment in an outer ring of congestion charging;
(4) It should have been combined with more positive measures to show people that the car is simply no alternative to cycling;
(5) The purpose of the zone was later watered down and combined with the Low Emission Zone, which confused people, as did the proposal for CO2 charging--both good initiatives, of course, but not what it said on the tin.