Thames Design
The Thames Barrier
The Thames Barrier is a major part of the flood defence system protecting London against rising water levels and tidal surges. The capital's defences also include additional floodgates at strategic points, like the Barking Barrier, and raised river embankments.
| a | b | c | d | e |
| f | g | h | i | j |
| k | l | m | n | o |
| p | q |
a
Navigation lights show red . (closed to shipping) or green . (open to shipping) for each navigational opening.b
Pier roofs made of timber with a maintenance free protective skin of stainless steel sheets. Iroko timber used for the laminated beams and European pine as part of the 3 layer skin.c
Rocking beam moved by linkages from two hydraulic cylinders that work in opposite directions. Pulling on the upper linkage and pushing the lower linkage raises the rocking beam. A connecting link between the tip of rocking beam and gate arm transfers the beam movement and makes the gate rotate.d
The dualpurpose shift and latch mechanism can be used to hold a gate in a particular position, move the gate into the underspill position or effect part of the movement to the maintenance position. As an extra safety measure, it can also be used to move a gate to the normal defence position.e
A gate arm (1100 tonnes) rotates about a trunnion shaft. A large part of the arm contains cast steel blocks to counterbalance the weight of the gate. Wooden rubbing strips protect against damage by ship impact.f
The rising sector gate leaf (1500 tonnes) is bolted to the gate arm at each end. The gate structure is cellular and allows water and air to enter and leave. High strength steels used in thicknesses up to 50mm. Steel protected against corrosion by 40 tonnes of paint and 20 tonnes of sacrificial anodes.g
Gates are normally rotated by machinery at one end only. In extreme circumstances both sets can be run simultaneously.h
Crane on each pier for machinery maintenance.i
Trunnion shaft (like a stub axle) fixed to pier.j
Cill made of concrete in cellular form. Largest ones weigh 10,000 tonnes.k
The 200mm wide space between the gate and the cill is made narrower at each edge of the gate, reducing to 75mm. This prevents debris large enough to jam the gate getting into the slot.l
Twin tunnels carry duplicate power cables, services and drains between piers and control building.m
Each central pier is 50m from top to bottom, 11m wide and 65m long. Incorporates main machinery rooms, service routes, stairways, a lift, a local control room and supports to adjoining cills. Pier penetrates 15m into river bed.n
Retained section of cofferdam piling shown here. Cofferdam piles were up to 39m long and penetrated up to 24m into the river bed.o
Up to 6 tonne blocks of stone on a filter layer to protect riverbed against scour from fast moving water.p
Alluvial gravel or Thanet sand.q
Chalk.© Thames Barrier Park, UK 2003