Q: When is a bridge not a bridge? 

A: When it’s a privatisation of public space


London’s proposed Garden Bridge

A Mayoral decision was recently taken to revoke the approvals given by the previous Mayor in 2015 for the ‘Garden Bridge’ project across the Thames in central London. The revocation relates to ‘three guarantees’ with the Port of London Authority, Westminster City Council, and the London Borough of Lambeth, intended originally ‘to help…progress the project’.

What was proposed as a ‘new form of public space’ for residents and visitors alike, in other words the proposed ‘garden bridge’, will not be built – there will not be a bridge. The decision was also made on the basis of cost. The Mayor indicated, in a letter to the Garden Bridge Trust, that he would not ‘…allow additional taxpayers’ funds that I control to be spent on this project’.

A total of £37.4 million of public money has been spent to date, although construction has not started, and the Garden Bridge Trust (after several years negotiation) have not yet reached agreement regarding use of the proposed South Bank site of the bridge.

Recent estimates suggest, the bridge would cost £200 million to build, and an unknown amount to maintain into the future. Despite a cost-benefit analysis suggesting benefits would exceed costs over a 60-year period there have been serious concerns that costs would escalate and a public body would be liable for future maintenance.

The garden bridge has proved highly controversial, in terms of the original idea (‘a garden across the Thames’), lack of clarity over the nature of the project (an ‘iconic design’ or a bridge), the design competition and award of contracts (suggestions these were flawed), and in its business case (a mix of public and private funds for construction, with future liabilities to be met by public funds).   A key issue, that has not been adequately addressed, is that the structure was never intended to be ‘a bridge’ in the accepted sense of the word, i.e. a structure built to enable people and goods to overcome an obstacle.  The focus on the structure as a footbridge was only a secondary objective, it was initially conceptualised as a ‘garden’ over the river with restricted access, an enclosure of public space.  As such it is an example of the privatisation of public resources for private gain that is occurring in urban areas everywhere.


Characteristics of bridges

Traditionally bridges have been considered as ‘toll’ structures.  Bridges requires significant capital investment, with no advantages for private sector funding unless a benefit stream derived from a crossing charge is guaranteed by government authority.  We still have toll bridges managed by private companies, often established by Act of Parliament.  Examples include the 5p per car to cross the Swinford Toll Bridge over the Thames near Eynsham  (first opened in 1769), the £1 to cross the Whitney Toll bridge over the River Wye (opened in 1774), and the current cost of £6.70 per private car (up to £20 for larger vehicles) to cross the River Severn on the M4 going into Wales (opened 1996).

Whitney Toll Bridge, River Wye

In terms of the economic resource characteristics, bridges are considered as toll (or club) goods.  A ‘toll’ good is one where utilisation is ‘non-subtractable’ or ‘non-rivalrous’ in nature (at least until congestion occurs), and where it is relatively easy to exclude people.  A non-subtractable good is one where use by one person does not diminish the availability or value of that good to another person.  With a bridge, one person’s use does not affect another person’s use – at least until traffic slows through congestion.  Although there are ‘public good’ aspects to bridges it is easy to exclude people and control access by charging a toll.  The toll avoids congestion as well as providing a revenue stream to pay for maintenance.  Toll goods are most easily delivered through creation of a monopoly, established to maintain a bridge and collect revenues.  The magnitude of the toll, or charge is established by the level of savings to the user of not having to make a much longer journey, and the potential benefits from being able to access ‘the other side’, whether for economic, or social benefit.

A bridge does not have to be managed as a club good – it can be managed as a public good, where a public authority manages the upkeep and the aim is to maximise social welfare.  Jules Dupuit, in his work on marginal utility and consumer surplus, showed as long ago as 1848 that social welfare is maximised when tolls for infrastructure such as roads or bridges approaches zero.

In places where large numbers of users within a community might benefit from unrestricted access, it can be more economically efficient for a local authority or government to provide a bridge as a ‘free’ public good, i.e. no charge for use, the cost of providing the good is met by all those in the society benefitting from provision of the good.  For example, in a city centre such as London or Paris, where individuals might want to cross a bridge multiple times in a day, and a charge might reduce interaction between different parts of a community, or where imposition of a barrier to extract a toll might slow down or reduce the flow of people and goods. Theoretically even those who never use the bridge benefit indirectly, as the additional benefits to society should outweigh the overall costs of providing the resource free of charge


The Garden Bridge – ‘a gift to the people of London’, a public good, a toll good, or private property?

As noted above, bridges are usually established where there is a clear identified need and/or demand for a crossing.  The demand guarantees an income (or demonstrates an improvement in social welfare) sufficient to justify paying for construction and maintenance, whether in the public or private domain.  The proposed garden bridge across the Thames in London is different.  It is situated in an area of central London with multiple crossings.  The need for an additional crossing has not been established through demand, the idea for the bridge has come from the supply side.

The fact that the Garden Bridge Trust has not managed to raise sufficient private sector funding is an indication that the bridge is not considered an efficient use of capital, hence the need for public funding.

There is a lack of clarity about the nature and purpose of the proposed bridge that makes the property rights difficult to determine, and confuses any attempt to determine the value of the structure to the residents of London.  The Garden Bridge has been called ‘a gift to the people of London’, but one that comes at a cost, and it also has characteristics of a public good, a toll good, and private property, which are described below.

Looking towards Blackfriar’s Bridge from Waterloo Bridge, The proposed Garden Bridge would cut across this view landing on the North Bank of the Thames – behind the white boat with 2 small masts.

Gift characteristics

The Garden Bridge was never originally justified on the basis of being a bridge, of providing a crossing point that would benefit local residents through reduction in travel time or costs.  The idea was to create a ‘garden’ across the river as an ‘iconic structure’ that would demonstrate the creativity of London and act as an additional draw for tourists (i.e. it was not about creating benefits for residents).  It was not intended as a gift in the sense of ‘something freely given with nothing asked in return’, it was more of a gift in the sense of the ‘gift economy’, where giving of a gift is explicitly part of an exchange culture where something is expected in return.

In this case the gift required public money to support construction, and public authorities to accept liabilities for future upkeep and maintenance, for an undetermined period of time into the future.

Public good characteristics

A bridge covered in a garden over the river, with no charge on access, and capacity to stop and look at the views and enjoy the gardens clearly has the characteristics of a public good, much like a public park.  Maintenance would all be paid for out of the public purse and like many public parks it was also proposed that the garden bridge would close at night, and have security personnel to ensure order.


Toll good characteristics

The bridge also demonstrates characteristics of toll (club) goods and private goods.  In this case monopoly power to manage the bridge has been granted to a Trust (The Garden Bridge Trust) that will set the rules controlling the level of use, and potentially charge fees.  In effect, the Trust will act much like a club in setting the rules about who can be a member, who can be allowed to utilise the space, and in what way they can utilise it.  Some proposed rules have already been suggested, including:

  • Only pedestrian travel will be allowed (cyclists can only push their bikes across)
  • Access will be controlled to limit the number of users at any one time (implies some form of gate and queuing system)
  • Limits on what people will be allowed to do (e.g. no playing of music or anything else which the owners might decide is not suitable)

Essentially the Trust will decide how the garden can be utilised and make use of CCTV, mobile phone tracking technology, and private security to enforce their rules. Those that do not like the rules do not need to ‘join the club’.

Private good characteristics

The ‘bridge’ also has characteristics of a private good.  It will have the status of private land,

and ‘people will be invited onto the bridge for the purpose of crossing it or visiting the gardens’.   Use will be restricted, it will be closed at night and at certain other times (a maximum of 12 events per year is suggested, the general public will be excluded to enable selling of the space for ‘private functions’ (e.g. corporate events), deemed essential to provide part of the finance to pay for the bridge.  During these events the Trust appears to have a free rein in determination of how the space will be used, subject to local bye-laws, much like a private good.

The exact nature of the proposed ‘garden bridge’ is thus unclear, yet the Trust would be granted control over the resource, which can be conceptualised as a semi-private ‘garden’ space, open to limited numbers of the public at certain times, but also available for hire at the right price.  Thus, what was characterised as a ‘gift’, is one where the private owners remain very much in control of how it should be used.  The confusion over the nature of the project is mirrored in the mix of private and public funding proposed to pay for construction and upkeep, and the lack of clarity in the property rights.


The costs of turning a garden into a bridge

The Garden Bridge was originally conceived as a garden that would become “a key and iconic tourist attraction right in the heart of the capital city”.  The nature of the bridge as a crossing point over the Thames was always secondary in nature to the other claims made for the structure, though the business case relied partially on monetising the benefits of walking and reductions in travel time from a new crossing point.

Transport for London (TFL) developed the business case, developing a series of arguments in support of the project and incorporating a cost-benefit analysis.

Underneath the ‘new’ Severn bridge crossing

A key focus of the TFL report was to demonstrate how the bridge would contribute to key ‘London Plan’ policies suggesting it would be a ‘landmark’, ‘improve access’, ‘enhance the cultural importance of the south bank’, ‘maximise benefits for public health and climate change’, promote a strong and diverse economy in London through creating new jobs and supporting existing jobs’, ‘improve connectivity’, provide new park space, and create a new cultural icon’.

The report also suggested more indirect benefits including ‘removing social barriers’, creation of an ‘innovative design that will inspire people’, ‘improving academic performance’, and help in ‘maintaining world-leading national museums and galleries, and supporting the museum sector’, as well as a means to encourage walking and so reduce greenhouse gas emissions.  The evidence for many of these arguments was tenuous and limited.  Surprisingly, out of five alternative options considered, only the garden bridge met all the project objectives, while the capital costs including, ‘ongoing funding’ were identified only as a ‘slight negative’ in the assessment.

In terms of costs and benefits the net present value (NPV) of the project over 60 years was calculated at £273 million, three times as much as any other option considered in the analysis.  However, a large proportion of the benefits were based on anticipated increases in residential property values in areas around the bridge, rather than in the form of benefits to users of the garden bridge.  The argument was made that because the distance between Waterloo and Blackfriars Bridge was 850m (suggesting one is never more than 425m from a bridge, or around five a minute walk) there was a “missing link for pedestrians”.  The report itself suggested that ‘…the maximum saving was likely to be around three minutes for a trip between for example Temple and the London Eye. A minimum of 20 seconds was calculated, which accrued to trips for example, between the Tate Modern and Covent Garden.’  There was no consideration of any displacement effect in calculations (i.e. to what extent the project might displace foot traffic from other bridges), and no estimate of deadweight (the extent to which it might be duplicating resources that already existed).

In economic terms, where public funding is utilised,  the question is one of whether a project results in an overall increase in social welfare, but the decision should not be made on the basis of a single cost-benefit ratio since these forms of analysis are seldom inclusive, and are based on assumptions regarding discount rates, estimated numbers benefitting in various ways (e.g. health implications, reductions in walking time) and predictions of future levels of property values, use of the bridge, and costs.  Small changes in the assumptions on which calculations are based can result in very different outcomes from such an analysis.  The value of a cost-benefit analysis is helping decisionmakers to understand which factors contribute most to costs and benefits and how those values change with small changes in predicted impacts (i.e. how ‘sensitive’ are they to changes in assumptions on which they are based).  Just as important are the questions of who loses and who gains from such an infrastructure project, and whose property rights are affected.

In terms of the Garden Bridge those who gain include the Garden Bridge Trust, who gain access and control of a new resource underpinned by public money, that can be used partially as a private good.  The extent to which London might gain is not demonstrated by the evidence in the TFL report.  The extent to which residents in the vicinity of the bridge might gain is unclear.  The TFL report suggests property owners and retail business on the north bank might improve, while on the south bank there was considerable opposition to the bridge.


Bridges are public goods

Bridges are not just crossing places, they can also add to cultural aesthetics of a place, they can come to symbolise character of a place, for example the Golden Gate Bridge in San Francisco, the Brooklyn Bridge in NYC, Tower Bridge in London, the Lanchid (Chain Bridge) across the Danube in Budapest, the old and new suspension bridges across the River Severn.  They can be admired in their own right as marvels of engineering or good design, and this was clearly part of the original idea, but bridges also have to be functional.  Building a bridge as a structure to hold a ‘garden’ and then to control access to the resource in order to maximise some unexplained ‘experience’ is not a functional use, it is simply creating a semi-private shrubbery in a public space.  Such a structure is not a bridge, it is an enclosure of an existing public resources, in this case the land on either side of the river where the bridge will be situated, and the taking of the existing iconic views currently widely available to the public across the Thames from the existing bridges, buildings, and river banks.

The planning authorities of London have made the right decision, but they need to strengthen their understanding of why it is the right decision.  Arguments based solely on costs to the public purse are limited in terms of the factors taken into account and how they are monetised, and liable to alter on the basis of changes in assumptions on which cost-benefit calculations are based.  There is a need to start recognising not just the monetary value but the rights to the shared resources we have in urban areas, to clarify which are public and not amenable to privatisation, which spaces belong to all the people, and which are not available to city governments to dispose of, or sell off as they wish.  In a time of austerity, it is even more imperative to recognise the ‘public value’ and need for protection of shared resources.

Decisions on how to use public resources requires input from the full range of stakeholders, including residents, users, and community organisations, not just city officials and politicians.  There is a need to start looking at our urban spaces as commons – the open spaces, the streets and squares, trees, parks, gardens, views across the built landscape, clean air and water – where the property rights to those resources are shared in common by all the residents of a town or city.  We need to find ways to improve governance of shared urban resources such that local residents and users have a say in how they are to be used.  There is a need to develop new mechanisms for how the urban commons can be kept available for current and future generations, and protected from those who would enclose the resources and spaces we all share.


Q: When is a bridge not a bridge?

A: When permission is refused for the taking of public space using public funding, for private gain.

View from South Bank close to where the Garden Bridge would be located