REIDsteel Flood Protection Systems

REIDsteel design, manufacture and erect both permanent and temporary flood protection systems including barriers. These can be erected on tarmac or concrete surfaces, as well as on grass or earthworks. The flood protection steel barrier can be anchored down with steel spikes or steel spade anchors.

In some cases, existing kerbstones or walls may be sufficient to resist thrusts. If there is enough space to make optimum flood barriers, there may be no need to anchor the barriers at all. Steel flood protection can be waterproofed with membranes or drilling mud.

Each flood prevention situation is different and no general examples can be shown. If you have any queries, please contact:

Please note that the flood protection and flood prevention steel structures are not held in stock. They have to be designed for the precise situation, drawn, manufactured, galvanized and delivered.

Flood prevention diagram

In a flood, the level of the water around the bridge rises, and the speed increases. Not only that, but trees and other debris are carried downstream. Flood damage can happen for several interlinked reasons:

1. Large floating objects can impact the bridge with a high amount of energy.
2. Floating debris will accumulate upstream of the bridge, underneath and even over it. The debris applies a pressure on the bridge pushing it downstream, and lifting it up.
3. The debris reduces the cross sectional area of the flow at the bridge, which increases the water height upstream, and increases the water speed around the bridge abutments and piers.
4. The water speed scours the river bed underneath and around the bridge, undercutting the piers and abutments.
5. The water level rises on the approach roads, cutting through the roadway, undermining the abutments and destroying the wing walls.

So how do we design flood resistant bridges?

The first step is to keep the deck above the level of the flood, so we make the lowest part of the bridge higher. A through-truss or stayed bridge does not have much structure below the roadway. The depth of the roadway is reduced to a minimum so that water can flow through it.

We would like to have a concrete deck on our steel because it is much heavier than a wood or metal deck, and will resist uplift, and because the concrete deck makes an excellent shear resisting member, making it difficult to bend the bridge sideways.

If possible, the bridge is clear span, so there are no piers to undercut. The abutments should be well protected below and above normal water levels to prevent erosion. If the bridge is on a wide flood plain, the bridge deck and the abutments should be higher than the surrounding land, with a ramp up at both ends, and in this way the flood is relieved by going around the bridge – it is much easier to fill a hole in the approach road than to replace a bridge.

REIDsteel highway bridges can be made up to 200m span. A large part of the cost of a bridge is the design process, but our bridges are pre-designed for a number of different spans and widths, so much of the cost can be avoided.

Our bridges have ‘lost formwork’ on which it is easy to pour a thick strong heavy concrete slab. We can design them to be transported and assembled using light equipment in a variety of differing gap shapes. Describe your bridge problem with us by email. I hope we can help you.

REIDsteel offer a range of flood protection systems and flood defences including steel flood barriers as well as flood resistant bridge design.

Rollo Reid
C Eng FIStrucE, Director, Reid Steel.