The Increasing Costs of The Garden Bridge

19 Jun 2016

The figure of £175m for the Garden Bridge is constantly repeated by the media, the Garden Bridge Trust, Sadiq Khan and TfL. But how did we get to that figure? And how accurate is it for completely untested engineering and architecture which has apparently eaten up nearly £40m before even getting all the permissions in place?


When the Garden Bridge was first proposed it was for an entirely different location. Joanna Lumley had decided her vision should be located just to the west of the Millennium Wheel (“Very few things would be put out by the position I have chosen”) and she pitched the concept to Prime Minister Gordon Brown as a memorial to Princess Diana. Guesstimated to cost around £19m, Brown wasn’t interested, and neither was Ken Livingstone after the PM passed her on to then Mayor of London who also rejected the folly.



By the early 2000s she had found a new location for her memorial project – the current proposed site – and had got Thomas Heatherwick on board who sketched out a new design which she started getting connected friends in high places to support.

In 2012 Lumley lucked out when old family friend Boris Johnson was elected as the new mayor, so she wrote a letter to him to sell her dream (“We have done a lot of groundwork as we had this idea several years ago”) and Johnson set out to make it happen for her.

Early in 2013 he got TfL to create a tiny £60k competition (pdf) looking for a designer they would work alongside with to test “broad options” for a potential footbridge across the Thames in “a number of locations”.

They had never carried out a transport or business study and were not asking for designs or solutions, just a designer to collaborate with on a small feasibility study. But, despite Heatherwick getting his bid in after the deadline, not fulfilling the brief and deciding to propose a singular vision (which he had already been developing alongside Johnson, TfL and Lambeth Council) for a Garden Bridge in a singular location TfL suspiciously asked him to build Lumley’s folly.

But the bridge hadn’t been costed at this point and so all the engineering and costing had to be backwards-engineered to suit the pretty images submitted. Nonetheless, the Mayor and TfL were happy to throw around the £60m figure to the press, stating it was to be entirely privately funded


£60m – £100m

In July 2013 TfL had decided to give £4m to get the project to planning. They were now estimating it at between £60m and £100m.



Over the next few months Heatherwick and the engineers, Arup, started to think about the design a bit deeper than the pretty renders it was all hanging off. A few months later, in November 2013, the Garden Bridge Trust was created to deliver the project – headed up by Heatherwick Studio employee Bee Emmott. At this launch Heatherwick “bizarrely likened his design to the Titanic” and the new cost of £150m was announced. Shortly afterwards a House of Lords debate saw it described as “an expensive vanity project”.



Less than a year later, by the end of 2014 the cost of the project was being discussed at £175m and despite opposition from local residents, experts pointing out the lack of need for a crossing in this location and huge concerns over heritage damage as voiced by St. Pauls Cathedral here it was passed at planning by Lambeth Council.



Through the whole of 2015 and most of 2016 the Garden Bridge Trust maintained the £175m build cost, including contingency.

In August 2016 the Chair of the Trust appeared on Newsnight after a report of donors leaving the scheme and said the cost had gone up to £185m.

Because of the lack of transparency it is not known if this means that the GBT have also written off their contingency as well as added £10m to the cost, but with a reduction in pledged donations and an admitted increase in cost the funding gap was only getting larger.



The Garden Bridge Trust accounts published on January 10th 2017 included the line: “The last external estimate of the total project cost of the Garden Bridge was £185m but due to the hurdles still to be cleared and the ensuing delays the final cost could substantially exceed the formal estimate.”


“NORTH OF” £200m

On 7th April 2017 Dame Margaret Hodge published her independent report into the Garden Bridge. For it she interviewed key stakeholders behind the development, and in one of these the Chairman of the Trust, Paul Morrell, told Hodge “I think we’re now north of £200 million”.



How much “north” is unknown, with some experts estimating £250-£280m. With the Trust seemingly unable to increase their donations level to cover even the £150m pricetag, the expectation is that should they commence construction there is a very high risk that the public purse will be required to bail out project on top of the annual £3m+ maintenance costs.


The projected cost will only likely increase, due to:

Continued delays to the construction timeline

One of the most complicated building sites anyone could have in London

Hugely experimental engineering which is always hard to keep under budget

Build complications due to the construction of the Thames Tideway Tunnel

Further likelihood of a judicial review from Thames Central Open Spaces (donate HERE)



Bespoke materials and cladding

Unknown engineering works required to Temple station roof



It’s also worth noting that the GBT have apparently not added very much to their private investment pledges in nearly two years, but because they are extremely secretive with their figures and there is very little transparency on the details of funding and build cost there is no way to independently verify the £200m figure. Meanwhile, Sadiq Khan seems content to gamble public money and blindly trust the GBT where few others do as he continues to refuse to engage with opponents, the local community and independent experts which is all slightly concerning. The Independent suggests that he has fallen for ‘sunk cost fallacy’.


So what is the real financial cost (not including the £3.5m annual maintenance that Johnson decided the public purse would underwrite in perpetuity)? Until the GBT open up their books entirely to public scrutiny, a full independent inquiry is commissioned into the whole debacle and quantity surveyors and auditors are brought in to fully look over the project there is no way of knowing.



But lets’ look at a current example which could serve as a warning.  the new Hamburg Elbphilharmonie concert hall which is due to open in January 2017. Designed by Herzog & de Mauron was started in 2007 and was originally set to be completed by 2010 at a cost of £60m (that figure seems familiar…).

But costs incrementally increased and the estimate jumped up to just over £180m. By 2012 it was still a building site with a new cost of around £400m.

The current total is £620m but I am sure the German version of Joanna Lumley would be very pleased that Hamburg will be getting its vanity project eventually…

Without looking too deeply, one can see similar overspends in British developments – The Millennium Dome came in twice over budget for example.

How about Heatherwick’s experiences? His Blue Carpet in Newcastle was one and a half times over budget, failing instantly, while his B of the Bang in Manchester was completed two years late, twice over budget and it started dangerously falling apart before being melted down and sold off as scrap metal for £17k with Heatherwick agreeing to pay Manchester City Council £1.7m in an out-of-court settlement.


Well, that all bodes well for the Garden Bridge!



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