05/09/2014 07:52 BST | Updated 04/11/2014 05:59 GMT

Does London Need More Roads, or More Public Transport?

You will hear a lot of figures quoted in the next few years about the economic benefits of the proposed road river crossings in East London. The Atkins report paid for by Transport for London predicts that the Silvertown Tunnel and the Gallions Reach bridge will support up to "23,800 additional housing units" and up to "34,000 total permanent jobs." I have no doubt that Boris Johnson will be spouting these figures in the coming months, in the same way that Ken Livingstone quoted similar figures about the Gallions Reach Bridge after Atkins wrote the same kind of nonsense over a decade ago.

The previous Atkins report and Transport for London's (TfL) economic case was demolished by several leading academics at the 2007 public inquiry. Whilst I don't have that kind of expertise to hand, I would like you to consider a few concerns I have about the new figures.

The most obvious is whether 25,500-34,000 people could actually squeeze across the new road crossings and get to these new jobs that have miraculously appeared as a result of spending a billion pounds on steel and tarmac? If we delve into their technical reports, it appears that between 6-9am, around 10,000 would be going off to work every day on the newly tolled roads across the river.

You may have noticed the problem here. Atkins says that the bridges will support up to 34,000 jobs but only 10,000 vehicles will be using the crossings. Some of those cars may have more than one person and TfL may actually lay on some buses, but the truth is that the Atkins report doesn't deal with real things. It claims that these commuting drivers will 'support' further jobs and businesses, presumably at new petrol stations.

When either the Mayor, or TfL make predictions about the future with new bridges, they cherry pick their assumptions to make this future as bright as possible.

For example, TfL have been telling the public the bridge will actually reduce traffic. How do they pull this magic trick? Well, the existing traffic modelling done by TfL predicts a huge increase in the number of vehicles in east London between now and 2021. Their projections on how the river crossings will relieve congestion are then calculated on this assumption that East London will already be even more clogged up than it is today. When you look at the TfL maps at the public consultations you are given the impression that traffic will be reduced on many key roads. But actually it could be a big increase on what actually exists now.

The Atkins report performs a similar trick in reverse on the housing figures. Whereas they take the Mayors' expectation of traffic growth as gospel and say the crossings will reduce that on key roads, they question the Mayor's housing numbers and then say the crossings will increase them. They claim that the Mayor will only be able to deliver 70% of the new homes he is predicting for the area by 2025. That is then their new starting point, with the river crossings bringing forward an additional 18,000-23,800, which brings us (more or less) back to what the Mayor is predicting.

The report predicts that the jobs will mostly be around Canary Wharf, the Royal Docks and Stratford, whilst the biggest potential for housing is in Greenwich and Bexley. It flags up that Newham and Tower Hamlets on the north side of the river suffer from higher unemployment than anywhere else in East London and they also have the biggest employment opportunities on their doorstep. It then recommends that we build road crossings so that people can get access to these jobs from Bexley in south London which has a third of the unemployment suffered by those boroughs on the north side of the river.

The mind-set which permeates the report is neatly summed up in their calculation that Bexley and Greenwich could potentially be able to build up to 29,000 extra dwelling units as a result of the increased 'connectivity' which comes from the proposed road bridges. The logic being that the 72,000 people who come to live in these new buildings will have easy access to car parking, so that they can take advantage of the newly built road crossings. Except this is congested and polluted London, where traffic already goes at a crawl and adding more cars will decrease the 'connectivity' as we increase delays. The last thing London's economy needs is more cars clogging up our existing roads.

Wouldn't we be better off extending Crossrail East and the DLR south? We have clear evidence that public transport does improve access to jobs in London. In fact, a recent study by Nationwide showed how house prices in London are £42,000 higher around tube stations. I've yet to find similar research claiming that living besides a dual carriageway in London adds value to your house. Shouldn't we be sorting out London's traffic by expanding the bus network, building more cycle lanes and financing it from a pay as you go driving scheme? I'm no expert, but it makes much more sense than what I'm hearing from people who want new roads and more pollution.