Guidance

The Thames Barrier

How the Thames Barrier works, and when it is scheduled to close.

From:
Environment Agency
Published
25 April 2014
Last updated
1020 March 2025 — See all updates

Applies to England

The Thames Barrier is one of the largest movable flood barriers in the world. The Environment Agency runs and maintains the Thames Barrier as well as London’s other flood defences.

You can:

Photograph of the Thames Barrier

The Thames Barrier

Forthcoming scheduled closures

Planned tests of the Thames Barrier in 2025

The Barrier is operated once a month for maintenance and test purposes. Details of the next planned closures are listed below.

Note these times may change because of a particular experiment or test which engineers need to carry out or because of the weather. The closure and reopening of the gates may start up to an hour before the listed times.

Occasionally closures may be cancelled at short notice due to the Thames Barrier being closed in that month for flood defence purposes or navigational reasons. If you plan to come and watch a test closure, call us the day before to check it is going ahead.

Date Day of the week Approximate river closure start time Approximate river closure end time
20 March 2025 Thursday 09:40 12:10
17 April 2025 Thursday 09:45 12:10
19 May 2025 Monday 11:10 13:40
16 June 2025 Monday 10:30 13:00
14 July 2025 Monday 09:50 12:20
12 August 2025 Tuesday 09:45 12:15
7 September 2025 Sunday 07:15 17:15
9 October 2025 Thursday 09:10 11:40

Contact us by emailing thamesbarriertheview@environment-agency.gov.uk

Forecasting closures

The Environment Agency receives information on potential tidal surges from:

  • weather satellites
  • oil rigs
  • weather ships
  • coastal stations

They can forecast dangerous conditions up to 36 hours in advance. The barrier will close just after low tide, or about 4 hours before the peak of the incoming tide surge reaches the barrier.

Information comes from a range of mathematical computer models that forecast expected sea and river levels. This is supplemented by data from the Met Office and real-time information provided by the UK National Tidegauge Network. This hydrological and meteorological data is fed into the control room every minute from a wide network of tide and river pressure and wind gauges.

The decision to close, or not, is based on a combination of 3 major factors:

  • the height of the tide (usually a spring tide) measured at the Thames Estuary
  • the height of the tidal surge, which naturally accompanies each tide
  • the river flow entering the tidal Thames, measured as it passes over Teddington Weir

Find up to date data for river and sea levels at the Thames Estuary and Teddington Weir.

The barrier has no individual trigger level for closure. The closing process is guided by a mathematical matrix that considers the river flow, tide and surge at the time. The final decision for closure lies with the Thames Barrier Duty Controller.

How the Thames Barrier works

The Thames Barrier:

  • spans 520 metres across the River Thames near Woolwich
  • protects 125 square kilometres of central London from flooding caused by tidal surges

It has 10 steel gates that can be raised into position across the River Thames. When raised, the main gates stand as high as a 5 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. This is to reduce the risk of river flooding in some areas of west London including Richmond and Twickenham.

The Thames Barrier will then remain closed over high water until the water level downstream of the Thames Barrier has reduced to the same level as upstream. This is a managed process to provide for different circumstances, and takes about 5 hours. The Thames Barrier is then opened, allowing the water upstream to flow out to sea with the outward bound tide.

You can watch a video that shows how the Thames Barrier works:

a video of how the Thames Barrier works

Thames Barrier closures

The Thames Barrier has been closed 221 times for flood defence purposes, since it became operational in 1982 - correct as at 16 April 2024. Of these closures:

  • 119 were to protect against tidal flooding
  • 102 were to protect against combined tidal/fluvial flooding

Thames Barrier closures

If you have an enquiry about the Thames Barrier, or would like to receive a project pack, email: thamesbarrierenquiries@environment-agency.gov.uk.

The future of the Thames Barrier

The Thames Estuary 2100 plan sets out how flood risk will be managed in the Thames estuary to the end of the century and beyond. It also recommends what actions the Environment Agency and others will need to take in the:

  • short term (the next 25 years)
  • medium term (the following 15 years)
  • long term (to the end of the century)

The plan is based on current guidance on climate change, but is adaptable to changes in predictions for sea level rise and climate change over the century.

More information can be found on the Thames Estuary 2100 page.

Visiting the Thames Barrier

New Thames Barrier cafe and information centre

The View and Information Centre (Thames Barrier Estate)

The Thames Barrier Information Centre is a small exhibition where you can learn about the construction of the Thames Barrier and how it works. There is a working model of the Thames Barrier and virtual technical tour along with other films and displays about flooding and the environment.

Each package has a personal guide for your group who will show you around the Thames Barrier Estate.

Our guides will cover topics including the history of the river and the risk of flooding in London, the environment and wildlife of the Thames.

Packages for group talk – available every day – need to book in advance:

  • Economic package – up to 15 people, all ages - £175.00£184.00
  • Child group talk – up to 30 children - £201.00£218.00
  • Child luxury group talk – with activities, up to 30 children - £225.00£244.00
  • Adult group talk – up to 30 people - £225.00£244.00
  • Technical presentation – over 16 years old, up to 30 people - £250.00£270.00

Note there is no access on to the Barrier.

If you would like to book one of our packages, send an email to thamesbarriertheview@environment-agency.gov.uk. Note we need at least a week to process any booking form, as our guides are available just when requested.

The Thames Barrier Information Centre will be open only on Saturdays from 5 April to 25 October 2025. There is no need to book in advance to visit it. The ticket can be bought at the entrance, from 10:30 to 15:30hours.

Tickets prices:

Adult: £6.00

Senior/Student: £5.50

Child: £4.80 – Child under 5 years old is free.

Disabled: £4.50

Family ticket: £16.00 (2 adults + up to 3 children)

Our outside toilets downstairs, disabled lift and car parks will continue to be open 7 days a week between 9am and 5pm.

For further enquiries, telephone 0208 305 4161 or email thamesbarriertheview@environment-agency.gov.uk.

Conference room hire

The Thames Barrier View Conference Centre also has rooms to hire that offers spectacular views of the Thames Barrier and River Thames. The rooms are light and spacious and offer various room layouts to suit all occasions:

  • conferences
  • meetings
  • receptions
  • workshops
  • wakes

For prices, e-mail us: thamesbarrierenquiries@environment-agency.gov.uk.

Getting to the Thames Barrier

Rail

Charlton station is situated on Woolwich Road and is approximately a one mile walk from the Thames Barrier Site. Woolwich Dockyard station is situated near Church Street and is within walking distance. Woolwich Arsenal station is the most convenient station to take a taxi to the Barrier Site.

London Underground North Greenwich (Jubilee Line)

The station is approximately 2 miles from the Thames Barrier and only 5 minutes by taxi or bus (161 and 472).

Bus routes

Bus No’s 177 and 180 via Greenwich (stop at the top of Eastmoor Street). 161 and 472 from North Greenwich tube station.

London City Airport

The City Airport is situated in North Woolwich only a short distance from the North Woolwich Ferry crossing.

Updates to this page

Published 25 April 2014
Last updated 1020 March 2025 + show all updates

    3. Updated dates the Thames Barrier Information Centre will be open.

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