The impact of flooding on bridges and other transport infrastructure in Cumbria (HC 473-i)
Transport Committee 17 Mar 2010
Evidence given by
2.45 pm Cumbria County Council Andrew Moss, Head of Service, Highways and Transportation Kenneth Brooks, Business Manager, Cumbria Highways
ADEPT (Association of Directors of Environment, Economy, Planning and Transport) Michael Winter, ADEPT Bridges Group Chairman and Head of Engineering, Dorset County Council Graham Cole, ADEPT Bridges Group Secretary and Structures Group Manager, Surrey County Council Institution of Civil Engineers Amrit Ghose, Chair of Structures & Buildings Board
3.30pm UK Roads Liaison Group Matthew Lugg, Chairman, UK Roads Board Greg Perks, Chairman, UK Bridges Board
Network Rail John Dora, Principal Engineer (Climate Change)
Environment Agency David Rooke, Head of Strategy and Engagement
4.15 pm Department for Transport Rt Hon Sadiq Khan, Minister of State for Transport, Mostaque Ahmed, Divisional Manager, Regional and Local Major Projects and Roads Maintenance
Highways Agency Neil Loudon, Group Manager, Structures Policy and Pavements
Q10 Mr. David Clelland: It is not just a question of the volume and rate of flow of the water, is it? It is also a question of the debris which is carried in the water. You could do as many calculations as you like about how the bridge might stand up to a volume of water, but how can you calculate the debris, the gravel and tree trunks which are carried in the water and are colliding with the bridges?
Mr Moss: It might be worth observing here some of the technical design standards referred to by Mike just now relate to new build bridges. Some of our bridges are of a considerable age, 100 or 200 years old; some of them older. The bridges in Workington, Northside Bridge, the one which fatally collapsed, we think is around 100 years old, something like that. Our bridges do have an inspection programme. We comply with government guidance for inspection and for maintenance. It might help if Ken explained a few things that we do regarding that in a moment.
Q18 Mr. David Clelland: It is one thing assessing the likely damage made through volumes of water and debris but there is also the question of avoidance, is there not? What could be done, for instance, to avoid the likelihood of large amounts of debris, tree trunks, et cetera being caught up in the flood? Should something be done about managing the river and the general environment to avoid that sort of thing in future?
Mr Winter: Yes. It is probably a matter for the Environment Agency to talk along those lines rather than us but certainly anything we can do to avoid tree trunks and so on hitting the bridges would be very beneficial.
Mr Brooks: I would just like to go back to the very beginning and try to emphasise the extraordinary nature of this event. We had significant amounts of rainfall and it was very focused and only happened in discrete areas of our county. That is why it affected the bridge stock that we are seeing has been damaged. It did not come across any Highways Agency structures as such; it only came across one railway bridge and all the other bridges which have been affected have been masonry structures. The scale of the flooding was unprecedented, so the land management structure upstream of those bridges would not have anticipated rubbish and debris being picked up and the figures you have quoted talked about design standards of 1:200-year return; everybody else in Cumbria is talking about a 1:1,000-year event. It is of a much greater scale and beyond anything anticipated or expected.
Q25 Chair: What happened in Cumbria was seen as a 1:200-year occurrence. Do you take any lessons from that? Should a change be made on maintenance standards and reviews?
Mr Moss: My recollection is that it is more than a 1:200 occurrence in terms of the weather event. We were under the impression that it was much broader than that: towards 1:1,000-year event.
Q26 Mr. David Clelland: How do you know it is a 1:1,000-year event?
Mr Moss: A good question. That is anecdotally how our understanding of this has emerged. I would have to report back to the Committee to verify the specific detail on that.
Q56 Mr. David Clelland: Have you actually inspected your bridges following the floods and has there been no damage at all?
Mr Dora: We have inspected our bridges following the floods and we found some reduction in the bed of the river, which you would expect from the force of the water, but not deep enough to compromise the current integrity of the structure.
Q57 Mr. David Clelland: So it is not necessary to take any corrective measures following the floods as far as your bridges are concerned?
Mr Dora: We inspect, we make sure they are safe and we take further measures if we need to, as we have done.
Q80 Mr. David Clelland: We have mostly concentrated on bridges but we know from our visit on Monday that not only bridges were damaged but quite often roads were flooded and some roads were completely destroyed in parts because of the floods. Perhaps Mr Rooke would be best able to answer my question. How well protected is the rest of the country's infrastructure, roads and railways, against severe flooding events?
Mr Rooke: We undertook a survey of national infrastructure back in 2006-2007 and we published that just before the summer 2007 floods. We published that information back in June of last year and that shows that about 10% of roads in England are at risk of flooding and about 20% of railways, along with loads of other infrastructure like police stations, hospitals, schools, et cetera. The summer 2007 floods highlighted in a very vivid way and a tragic way for some just how much of our infrastructure is at risk from flooding and that is based on current risks; the projections are that with climate change those risks will increase.
Q81 Mr. David Clelland: So what lessons have we learned and what further measures are going to be taken to deal with that increased risk?
Mr Rooke: The Government asked Sir Michael Pitt to undertake a review of the summer 2007 floods. He published his report. The Government accepted all 92 recommendations and amongst them there was a recommendation that the Government should look at critical infrastructure. The Cabinet Office have set up a Natural Hazards Team and they have started their work to look at the impacts of flooding and other natural hazards on infrastructure. They carried out a consultation as to the sort of standards and the issues to develop a framework last year. The consultation closed in the early part of this year and they will be publishing a report later this year.
Q82 Mr. David Clelland: What priority does transport infrastructure have in terms of flood risk monitoring?
Mr Rooke: The Cabinet Office group has looked at transport, it has looked at energy, it has looked at water, it has looked at all the sectors, so that is a question really for the Cabinet Office. We have been able to supply information to inform the surveys and work that they are doing.
Q83 Mr. David Clelland: Do you have any examples of work which is being done on protection against floods specifically relating to transport infrastructure?
Mr Rooke: Not specifically on transport. We do in the water sector and electricity following the summer 2007 flooding. I am aware that work was undertaken but I cannot give you a specific example.
Q100 Mr. David Clelland: I was just wondering how concerned the Department was that the bridge collapsed and that the damage to bridges in Cumbria could occur elsewhere in the country and what lessons have been learned and what action has been taken.
Mr Khan: The first question that I asked as a lay person not an engineer was why the bridge collapsed. Could it have been prevented? Could anything have happened to prevent it taking place? I am not an expert but the experts told me that the sheer volume of water and the speed at which it was going and the scour and all the rest of it meant that no bridge could have withstood that volume of water. There is a question which is worth asking which is how should you manage the risks of a 1:200-year flood and that volume of water? Since records began there has never been more rainfall in a 24-hour period. The obvious concern I had as a lay person was that this was an old bridge, more than 100 years old and could it be for that reason that it collapsed. The answer was no, it was just the sheer volume of water; even newer bridges may not have been able to withstand that volume of water. To answer your question another way, what lengths do you have to go to to get bridges that withstand that level of water flow, which could happen every 200 years? Question: is it worth the cost in money terms? When Pitt did his review the issue he raised was that we should have bridges which could withstand a 1:200-year event which is the sort of levels we are talking about here.
Q101 Mr. David Clelland: We have heard that several times here today; in fact we started off with 1:1,000 and we are now down to 1:200. I am just wondering whether we might come down even further. The fact is that we do not know whether these events are 1:200 years or once every year for all we know.
Mr Khan: What makes it even more unknown, as the effects of climate change impact on communities, is that what is 200 years before the impact of climate change may not be so going forward. That is one of the interesting things about the Climate Change Act and the Flood and Water Management Bill. How do we adapt and make our infrastructures resilient to some of those things? The Highways Agency will be doing some of that work with the Environment Agency to make sure we adapt. Obviously there are three main bodies to look towards, Network Rail as the rail is crossing the bridge, local authorities for the sorts of bridges we are talking about in Cumbria and the Highways Agency in relation to theirs. It is worth Neil, who is an engineer, just touching on that.
Mr Loudon: I would draw the distinction between existing bridges and new bridges. For new bridges we work very closely with the Environment Agency, looking at the capacity of the structure and the form of the structure to cater for the 1:200-year storm. Obviously that is under review in the light of climate change as well. We work very closely with them and we will look and mitigate against the impossible effects of scour and erosion as well. When we are designing a new structure, we will take full account of the Environment Agency's requirements, 1:200-year storms, to look at the capacity of the structure and also the form of the structure as well and then look at the more detailed aspects of the design. For existing structures, one of the things we have done since Cumbria is look again at some of our standards and we are in the process of carrying out that review at the moment, looking at the hydraulic loading on structures, looking at our scour assessment and we have had quite a regime of scour assessment in place for a number of years. We are looking again at all of those standards, looking again at our inspection standards in the light of the experience from Cumbria. We have yet to get all the feedback, look at all those experiences and review our standards in that light.
Q111 Mr. David Clelland: I take what you say about local authorities having the powers to look after their own road network and that is entirely right. However, one problem which has been drawn to our attention today is that what tends to happen is that they tend to concentrate more on the bits you can see, potholes in the roads, and not on the bits you cannot see, which is the infrastructure and the strength and structure of bridges. In light of what has happened in Cumbria, are any new guidelines being sent out to local authorities about looking after the structure of the bridges?
Mr Khan: The starting point is that there is a statutory duty upon local authorities under section 41 of the Highways Act to make sure they maintain those infrastructures that they are responsible for. The law says they have to do so. Secondly, what we have done, working with the Environment Agency, working with UKRLG, is to try to see whether any adaptations are needed in the guidance in relation to what advice we give to local authorities. We are not the experts at DfT. The experts are the UK Roads Liaison Group, the engineers and others and they are renewing and adapting their guidance over time.
Mr Ahmed: In fact we provide the funding to facilitate a lot of the UKLRG research and we sit in their working groups with them, recognising that we at the centre are not actually the experts. It is they who are the experts and we fund and support them.
Q112 Mr. David Clelland: If there is a shortfall, if the amount of money which is allocated within the overall totals to local authorities for bridge maintenance is not being spent, is that because the allocation is too generous or the local authorities are just not concentrating on the work you say they should be concentrating on?
Mr Khan: It is because council leaders, councillors, have decided that other things are a priority. One of the things we could do is ring-fence this money so you must spend this money on road maintenance or on bridges. The problem is how we in Whitehall know what you are spending on your bridges and maintenance. I would hope that your local engineers, whom you as a local councillor had hired, would advise you what to spend. Just to agree with you, when I speak to officers around the country, they tell me that the highways service within councils is the Cinderella service. You are right that councillors would rather spend money on things they can point to and say "We did that" rather than the structures beneath water or things that you cannot see with your eyes. I can see the challenges councils have. I am sure you will agree that we have the same challenges in Parliament.
Chair: Local authority discretion certainly remains very important.
Q113 Mr. David Clelland: It would not so much be a question of ring-fencing or telling people what to do. It was just a question of what lessons we have learned from Boscastle, from Cumbria and whether there is new guidance or any revision of guidance as a result of those lessons.
Mr Khan: We will have a better idea. When we surveyed in 2007-2008 what local authorities were telling us was that 9% already had a completed transport asset management plan and 80% of others were working on theirs. We are going to survey again after the council election purdah ends and if the response is that there was not 90% plus - I expect to see 100% - then it means there are serious problems. If you as a local council leader do not know the assets you have and how poor they are, then alarm bells should start ringing, especially if you are one of the flood areas that Mr Loudon talked about.
Mr Ahmed: I would also like to point to the UKRLG's written evidence to you where one of their recommendations is "As a result of this inquiry ... UKLRG will wish to examine how their suite of codes of practice takes account of climate change" and we fund a lot of the research that they do and we support them in that.
Q123 Mr. David Clelland: We have talked a lot about bridges but there is also a question of the highways which were also flooded and the A66, which in that part of its length is a trunk road and is managed by the Highways Agency, was flooded and blocked for some time.
Mr Loudon: Flooded for 45 hours.
Q124 Mr. David Clelland: Indeed a viaduct, maybe 200 feet from the valley floor, had two feet of water in it because the gullies were not capable of taking the water away. Obviously this is a 1:200-year event but we do not know how often these things might or might not happen again in future. Were any lessons learned there, any alterations to be made to those sections of the road or anywhere else in the country because of the likelihood of severe storms like that?
Mr Loudon: I can only comment again from the Highways Agency perspective. There was fairly limited damage to the other infrastructure. There was a river adjacent to the trunk road which had some minor damage and is being repaired. There was some localised damage to some of the drainage and some of the carriageway surfacing but again it was relatively minor considering the nature and extent of the rainfall and the flooding. To pick up on your point, yes, of course when we do our survey and look at the vulnerability of our assets, I do not just talk in terms of structures, I talk in terms of the geotechnical, the earthworks, the drainage and the pavements themselves. We have to look at the whole infrastructure.
Mr Khan: One of the lessons we learned is in relation to drainage. We are now working much more closely with Defra in the Flood and Water Management Bill to have sustainable drainage rather than the presumption, when you build a highway or property, that you connect automatically to the sewerage system. It is that sort of foresight which was not there even ten years ago and we are trying to build in now and trying to make sure we do not have the problems in 10 or 20 years' time that we have now in relation to where the water runoff goes.
This is an uncorrected transcript of evidence taken in public and reported to the House. The transcript has been placed on the internet on the authority of the Committee. Neither witnesses nor Members have had the opportunity to correct the record. The transcript is not yet an approved formal record of these proceedings.
The full transcript may be read here.
|Promoted by Ken Childs on behalf of David Clelland, both of 19 Ravensworth Road, Dunston, Gateshead. NE11 9AB|