26 WINTER MAINTENANCE
Protecting roads from fl ooding
More than 16,000 miles of roads are at risk from fl ooding. Roger Patey, director of UK Flood Defences, examines what can be done to protect them
As we all know our climate is now at the mercy of extreme weather patterns and expected to be part of our changing climate. We have enjoyed a Mediterranean summer so who can blame us for putting to the back of our minds the very real potential of heavy and persistent rain and adverse weather conditions to come leading to signifi cant disruption, loss of services and trade, economic damage, major clear up issues and resultant loss of productivity and profi ts.
Our road networks are a vital part of the UK’s economic well being and ensuring our infrastructure is protected and kept open is vital for the future. But how prepared can we be and how can we avert and minimise fl ood risk at a realistic cost and of course where?
The initiatives by highways authorities and partner companies together with the Environment Agency will go a long way to providing a strategic plan for areas of regular fl ooding but it will never completely solve the issues affecting fl ash fl ooding and adverse weather conditions like we saw last year. Of course there’s no 100 per cent solution but there are ways in which we can minimise the disruption and damage fl ooding causes to our road infrastructure and the resultant economic cost. Environment Agency research shows that for each pound invested in fl ood defence saves £8 in cost of repairs and clean up and that doesn’t include the economic damage. The problem is we can’t invest everywhere where there could be a problem as it would be far too costly.
In Germany the situation is different as they use the fi re service as a task force to provide temporary defence for areas under threat. Defence products are held at regional centres either pre-fi lled and ready or fl at pack ready to move quickly to fl ood risk areas. Within the UK we have within our highways teams and
Flood defence products are held at regional centres
DECEMBER 2013
www.highwaysmagazine.co.uk
Once the road is overtopped nearby houses are quickly inundated. Four hours after the breach most houses in the village are affected.
The model shows that the elevated A309 holds back the fl ood water for 2 hours. This would give suffi cient time to evacuate vulnerable residents if the watercourse breach was monitored effectively.
partner companies, manpower to quickly set temporary defences. The problem is where to deploy and by how much?
Deploying defences
The Met Offi ce and Environment Agency have improved their forecasting models and can now predict with more certainty areas at risk including those areas under risk from fl ash fl ooding but how do you know where best to deploy defences without causing other fl ooding issues elsewhere? How do you ensure defence is set at areas where there is most risk of breach within the defences themselves?
UK Flood Defences are working in partnership with WSP Consulting who developed a computer model based on satellite communication to assess areas at risk and where to deploy temporary defences including where to set in place more robust defences in areas at most risk from breach (the images above shows an example of the computer model).
The company provides fast, effective temporary and semi-permanent fl ood defence to quickly avert fl ooding and see this approach and temporary defence as the way to avoid large-scale disruption.
The Met Offi ce and Environment Agency forecasting models now provide more accurate advance fl ood warnings, including fl ash fl ooding, giving enough time to protect the road network, utilities, businesses, essential services and local areas. Obviously solving a problem in one area can create fl ooding in another which is why the UK Flood Defences and WSP model is of interest. Add to this the creation of strategic regional centres where temporary fl ood defence products can be stored, possibly where salt is held, then we are some way to alleviating serious disruption to personal, business and ultimately economic loss to the UK economy.
The available workforce is already in place, either within partner companies or highways, and we now have with UK Flood Defences a temporary or semi- permanent system that is easy to set in place, is reusable, leaves no clear up waste and for a small outlay will avert unnecessary diffi culty.
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