The history of the redevelopment of Docklands has been dominated by the issue of transport. At first much of the Docklands area, particularly Canary Wharf, was completely inaccessible. There was the odd bus, a semi-defunct railway line and a lot o f roads which were all right in themselves for local use, but which quickly became hopelessly jammed at the access points to the rest of east London at peak hours.

It is hardly surprising, therefore, that a large proportion of public expenditure on revitalising the area has been spent on transport. So far, around £600m has gone on roads and £750m on the Docklands Light Railway. Indeed, Docklands will also soon boast the most expensive tube line ever built in Britain, the £1.8bn Jubilee Line Extension, as well as the most expensive section of road, the £300m-mile long Limehouse link.

There is no doubt that in the early stages Docklands transport was cobbled together as an afterthought. The Docklands Light Railway was just such a hasty response. It was envisaged initially as a cheap way of bringing people from the City to the Isle of Dogs and was originally going to be a tram system at street level, but that idea was quickly dropped. The first phase, opened in 1987 went from the Isle of Dogs to Tower Gateway, next to Fenchurch Street station in the City and cost only £77m to build. Now its various phases and additions have resulted in ten times that amount of money being spent on a railway that critics say is now the wrong type of system for Docklands' needs.

Ben Kochan of the Docklands Forum said "The original Docklands Plan envisaged a proper tube line but it was thought to be too expensive. Nobody now, starting from scratch, would build a light railway for the kinds of numbers of people working in Docklands."

Now, however, Docklands will be getting its own tube line. The Jubilee Line Extension should be completed by 28 March 1998 - a date bravely put forward by London Underground for the day it will "open for business". A spokeswoman for the line said that although some work had been held up because the tunnelling was being done by the same method used for the Heathrow Express - which suffered a collapse last October - the scheme was still on schedule.

The line has been dogged by controversy, partly because it was seen as no less vital for London's infrastructure than other mooted projects such as the Chelsea to Hackney tube line. Then with the collapse of Olympia and York, the developers of Canary Wharf, which had promised £160m towards the cost of construction, the start of work was delayed for over a year for negotiations with the banks which took over the development. The Government steadfastly refused to fund the whole project and eventually a deal was struck with the help of £98m from the European Investment Bank.

This was a turning point. Without the prospect of a tube line, the DLR would just not have been able to cope with the increased numbers of office workers in the development.

Ironically, the opening of the JLE will put the DLR, which is due to be privatised next year, at risk and makes it almost imperative for the line to extend southwards to grab a whole new catchment area. The £100m Lewisham extension scheme, which will include stations at Greenwich and Deptford and possibly at Cutty Sark - though the cost may rule this out -has been drawn up but the Government has insisted that it should be funded through the private sector. Four consortia are putting forward schemes for the funding which is complicated because the Government requires a certain element of risk to be transferred to the private sector. Therefore the return for the investor will be at least partly dependent on the number of passengers using the line.

Brian Abbott, the DLR's press officer, is confident that it will be built: "There has been a lot of interest and we are confident that a scheme can be drawn up."

The new section of the DLR to Beckton, opened late last year carries only 2,000 passengers per day partly because trains are only able to run to Poplar from where a shuttle service operates to Canary Wharf.

In contrast to the rest of the DLR, the extension to Beckton has been built before any development in the Royal Docks, the area it is intended to serve, has taken place. This has led to criticism that it is a white elephant which shows that either way the planners just can't win. Either they put in the infrastructure first and no one uses it initially, or they put it in afterwards when it is considered too late.