London Briefing Chris JohnsLondon mayor Ken Livingstone often manages to exasperate both friends and critics alike. Admirers of his successful introduction of the central London congestion charge include many other cities in the UK and abroad. If there is a congestion charging system coming to a city near you, Mr Livingstone will take some of the credit - or blame, depending on your point of view.

The mayor's determination to keep pushing the boundaries is evident from a raft of initiatives. Transport for London, the mayor's agency responsible for all aspects of London's rail and bus networks, as well as 580km of London's most important roads, has just announced the first introduction of digital technology designed to enforce parking regulations. Violators will be on the watch for a "smart car" bristling with global positioning systems, automatic number plate recognition cameras and DVD recording.

While there is no suggestion that the much-reviled traffic warden is destined for the outsourced scrap heap, there are many who live in hope.

The focus is on London's so-called red routes - those that comprise only 5 per cent of the roads but carry 35 per cent of the traffic. When junctions or bus lanes are blocked on these roads, the knock-on effects are always annoying and occasionally catastrophic. It's all about keeping the traffic moving, particularly buses.

If traffic wardens can be thought of as analogue enforcers, they have nevertheless managed to increase the speed of buses by 15 per cent in dedicated lanes in the past three years of tougher regulations. The new digital enforcers are thought likely to get buses moving more quickly.

The costs of being caught parked illegally on a red route are starting to look prohibitive. A standard parking ticket now costs £100 (€143), reduced to £50 for prompt payment.

While speed cameras often attract the charge that they exist merely to raise revenue, few have argued along similar lines for Ken's attempts to keep buses moving. There are 6.3 million bus journeys a day in London, the highest in nearly 40 years.

Such has been the success of the congestion charge, a westward extension to include parts of Chelsea and Kensington will be launched early next year. Many other cities have looked at London's scheme and have liked what they have seen.

But one group of people has not been that impressed. Many foreign embassies have refused to pay the congestion charge. This carries on a long tradition: cards with CD number plates have always attracted dozens of parking tickets that have rarely been honoured. Londoners have lived for years with the exasperation of diplomats claiming immunity from parking regulations. This abuse of diplomatic immunity has rarely received much comment from officials and politicians (probably because they abuse similar laws overseas).

Not surprisingly, Ken has stepped up to the plate and tackled head-on the alleged traffic violations of the US embassy. And diplomacy is not a concept that the mayor seems to have fully embraced. Mr Livingstone has referred to the US ambassador as a "chiselling little crook" for refusing to pay the congestion charge. A touch over the top perhaps, but I suspect that His Excellency has received the message.

Transport is vital to London's future. Improvements are necessary if the 2012 Olympics are to be judged a success. The UK depends on the success of the City: any survey of the foreign investment bankers - who contribute enormously to that success - always reveals a list of positives about London as reasons why they come here, "in spite of the appalling transport infrastructure".

Most people think London would be the perfect world city, if only we could move around with a little more comfort.

But things are improving, thanks partly to the initiatives introduced by Livingstone. The tube still suffers from decades of underinvestment but is, at the very least, not getting any worse. Road congestion is less, thanks to the charge.

Such incremental changes do little to dispel the pessimism over London's main problem - that's going to take many more years and a lot more money.

Chris Johns is an investment strategist with Collins Stewart. All opinions are personal.