APRIL 2014


www.highwaysmagazine.co.uk


Effects of fl ooding on roads


Arthur Hannah


Editorial board member Arthur Hannah discusses the impact that recent severe rainfall has had on the UK’s road network


It has been an interesting start to the New Year on the weather front with heavy winds and rain causing fl ooding in many places. The eastern side of the country appears to have been reasonably lucky by missing most of the worst gales, but the fl ooding around Milton Keynes is the worst I have seen in over 20 years. So much for global warming! Unfortunately by calling it global warming people get the wrong idea, as an extra degree or so in average temperature and an extra few centimetres of rain per year by 2050 hardly seems to be a problem. However, although the averages may not be changing much the extremes are becoming greater. The fl ooding that we saw at the start of this year is evidence of this. It should really be referred to as climate change because it is the extremes that are getting worse, which in average terms makes little appreciable difference. However, as we have seen this year it can make a catastrophic difference in the short term causing problems which can continue for many months afterwards.


When you consider what this does to the infrastructure we are all heavily involved with – the road network – then it is not diffi cult to see what problems lie ahead. One of the biggest factors in the deterioration of roads is the damage caused by water, especially when it gets into the layers. Roads that are submerged for any appreciable time are likely to suffer severe damage when the traffi c actually runs on them again. While they are fl ooded they may not suffer the damage of traffi c action but once the water has subsided and the traffi c runs over them again then


One of the biggest factors in the deterioration of roads is the damage caused by water, especially when it gets into the layers. Roads that are submerged for any appreciable time are likely to suffer severe damage when the traffi c actually runs on them again


the damage will begin and potholes and disintegration will occur. Roads that are not fl ooded are still seeing a huge amount of surface water during the storms and any potholes or surface fretting is an ideal location for the ingress of water into the lower layers, which with the pumping action of the traffi c will accelerate the deterioration of the road. This is happening on all classes of roads with many of our motorways looking more like canals during some of the heavy rainstorms.


Getting the message across


But then I suppose none of what I have just said is news to any competent road or highway engineer. The problem is, as usual, getting the message across to those responsible for the funds to undertake the repairs, the politicians. By the time you read this the results of the 19th Annual Local Authority Road Maintenance (ALARM) survey will have been issued. The ALARM survey, which is commissioned by the Asphalt Industry Alliance, is undertaken every year. This is a survey of all the authorities responsible for the road network and looks at the condition of the roads and what is needed to put them right


Potholes are an ideal location


for the ingress of water into the lower layers of a road


and how long this will take. Every year this survey shows a continued deterioration in the network and although it is widely publicised in the national press it does not seem to have the effect of the desired increase in budget for road repairs. I have no prior information on what this year’s survey will show, but after the severe wet weather and fl ooding this winter, it is likely to show further deterioration and a larger gap in funding.


The government has recently announced extra help to the tune of over £100 million to address the problems of road deterioration but this is little more than supplying a sticking plaster to your leg when in fact you have broken it and probably need surgery.


We do need to get the message across to the general public that neglecting the road infrastructure will only cause increasing problems which will be exacerbated by climate change. I am not sure how we get this message across as all attempts in the past appear to fall on stony ground. Unless the public pressurise the politicians then we will only go backwards and the road network will continue to deteriorate.


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