Lessons for government from the Garden Bridge fiasco

18 Aug 17

The Garden Bridge highlights the flaws in government infrastructure decision-making, says Graham Atkins of the Insittute for Government. He outlines three key lessons for the future.

The Garden Bridge, a pedestrian crossing across the Thames in central London, has long been mired in controversy.

The project finally wound down after Sadiq Khan announced in April he would withdraw Mayoral guarantees for future running costs, and the Garden Bridge Trust – the charity established to deliver the Bridge – announced it had been unable to raise private funds to meet these costs.

The Garden Bridge project typifies several flaws in government infrastructure decision-making, which future governments would do well to learn from. There are three key lessons:

Define the problem before considering the solution

Infrastructure investments work best as part of an overarching strategy, where individual projects address clear problems. Much like the dispute over HS2s objectives, there was confusion over what problem the Garden Bridge was supposed to solve.

The ‘strategic case’ for the bridge – the reasons for undertaking the project – tried to address too many objectives, including: improving pedestrian connectivity across the Thames; economic development; and supporting London’s tourist economy.

Without a clear understanding of purpose, it was difficult for government to determine whether the project represented good value.

Ensure the economic case is rigorous

Concerns have been raised about the accuracy of infrastructure economic appraisal, particularly with regards to ‘wider economic impacts’ such as job creation or increased productivity. These concerns were born out in the Garden Bridge, as shown in the Treasury’s 2014 review of the business case.

The Treasury rightly drew attention to the fact that the evidence for projected tourism and construction exports benefits was very weak. Worryingly, the case for tourism appeared to ignore existing government research which showed that projected increases in tourism spending for previous interventions usually failed to materialize.

The Treasury concluded that the project might be valuable although it was heavily dependent on “potential business and property impacts, where there are significant uncertainties”.

Given that the Bridge business case was produced in line with standard government guidance, this adds to concerns about the rigour of economic cases more generally.

We will return to the use of cost-benefit analysis for infrastructure projects, and how to improve it, in an upcoming report.

Ensure that uncertainty is understood

Decision makers need to have a good handle on uncertainty and risk in projects in order to make effective investments – and it is not clear that Transport for London did.

The majority of quantified benefits relied on assumptions about increases in property values which are notoriously difficult to forecast with any degree of accuracy. More concerning, these calculations were based on a methodology which risked double-counting the benefits.

This is because the projected increase in property values may simply have represented some of the additional business revenue streams modelled in a separate section of the business case.

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