Case study: the Thames Barrier

If a project goes over budget and over schedule, is it still a success? What if the project performs well, would you consider it a success?

Professor Rodney Turner uses the example of the Thames Barrier in London to discuss project success. The Thames Barrier has operated since 1984 and prevents the Greater London floodplain (except the easternmost districts), from being flooded by high tides and storm surges moving up from the North Sea.

The barrier was built because, historically, there were problems with flooding in London. Major events included:

• The London flood, 1928: 14 people drowned in London and thousands were made homeless.

• The Thames Valley flood,1947: the peak flow was 61.7 billion litres of water per day and the damage cost a total of £12 million to repair.

• The Canvey Island flood, 1953: 58 people died and it led to the temporary evacuation of the 13,000 residents.

The Thames Barrier was designed as a system to protect London from future floods.

How does the Thames Barrier perform in respect of the iron triangle?

Now, you will reflect on the project’s key features against the iron triangle using information sourced from Dalcher (2012).

Scope

The project's scope was to:

• mitigate the impact of storm surges in the Thames estuary

• protect the low lying areas adjacent to the Thames

• address the steady rise in water levels.

Cost

The project's financial record is unsuccessful because:

• the project was priced at £110.7 million in October 1973

• it was ultimately delivered at a cost of £440 million which is the equivalent of £1.6 billion in today’s money.

Schedule

In respect of schedule, the project is equally unsuccessful because:

• the initial plan called for four years of work

• construction actually took almost twice as long; luckily no floods occurred during that period.

How does the Thames Barrier perform in respect of its operation?

The Thames Barrier did not perform well in respect of the iron triangle, but does this make it an unsuccessful project? If you consider how the Barrier operates you might think differently about its performance.

As the UK Environment Agency explains (2017) the Thames Barrier spans 520 metres across the River Thames near Woolwich, and it protects 125 square kilometres of central London from flooding caused by tidal surges. It has 10 steel gates which raise into position across the river. When raised, the main gates stand as high as a five storey building and as wide as the opening of Tower Bridge. Each main gate weighs 3,300 tonnes.

The barrier is closed under storm surge conditions to protect London from flooding from the sea. It may also be closed during periods of high flow over Teddington Weir to reduce the risk of flooding in some areas of west London, such as Richmond and Twickenham.

The Thames Barrier then remains closed until the water level downstream has reduced to the same level as upstream. This process is managed to account for different circumstances and takes about five hours. The barrier is then opened, allowing the water upstream to flow out to sea with the outward-bound tide.

The barrier was originally designed to protect London against a very high flood level (with an estimated return period of 100 years): up to the year 2030. From this point onwards, the level of protection would be reduced but still kept within an acceptable limit. At the time of its construction, it was intended that the barrier would be used two to three times per year. London now uses it six to seven times per year and it works perfectly.

The Thames Barrier currently protects an estimated 1.25 million people, £200 billion worth of property and infrastructure, a large proportion of the London tube network and many historic buildings, power supplies, and other key buildings in the city.

The barrier has paid for itself many times since it started operating. This is an example of a great project success.

Please refer to the glossary to check any terminology you are unfamiliar with: Glossary of Project Management Terms

Coming up...

In the next section you will discuss project success with your peers.