Construction Essays – Thames Barrier Flood

Thames Barrier Flood

ABSTRACT

This is a paper regarding the Thames Barrier. I am trying to present a report on Thames Barrier which is a kind of barrier on the River Thames for flood control. It was constructed between 1974 and 1984. As situated at Woolwich Reach, this barrier is considered to be a remarkable construction. After its construction it was first used defensively in 1983. After that there was no looking back. From 1983 onwards it has been used over 100 times defensively. Till March 19th, 2008 it has got no competitor in its way. Being the world’s second largest movable flood barrier the Thames Barrier stands with all pride and superiority.

In this paper I am going to present some of the important things related to this great construction.

EXECUTIVE SUMMARY

The Thames Barrier located in the downstream of central London, United Kingdom. It is a magnificently well built mega-structure of the world. The purpose of this barrier is to prevent London being flooded. London in general faces seasonal high tide moving up from the sea all these exceptionally high tides are exacerbated by a storm surge. The Thames Barrier is raised for the duration of the high tide in order to prevent it from getting inside the city. As for the dealings with the low tide the Thames Barrier can be opened and as such it release water flowing down the Thames and in general circumstances backs up behind it.

The functionality of this Thames Barrier is very unique and is of great use to the people of London. It has been built across a 523 metre wide over the stretched width of the river, this barrier divides the river into four 61m and two 31m navigable spans. Along with these it also divided it into 4 smaller non-navigable channels between nine concrete piers and two abutments. Huge in structure and worth in construction, this is an amazing barrier ranking itself in the second position.

THE REPORT

The Thames Barrier is for me a remarkable construction and with its gigantic structure it has saved London for 100 times. In this paper I am going to explore all those aspects of this barrier that has made it world’s second largest barrier. I am also trying to find out how appropriately it has been built and how worth is its construction. The roles played by the government and the engineers and the contractors are also my concern. As the paper proceeds I discover certain things that need some kind of discussion and thus the target of my paper.

The Thames Barrier took a span of ten years to get constructed. It was started in 1974 and was finished in the year 1984. Its target was to control and to limit the damages that cause by the seasonal flood of London. It is at the Woolwich Reach and from the day of its launch it has protected London from 1oos of disasters. There are of course some amounts of variations too and that is what the main objective of this paper is.

The construction is not only unique but is very innovative among its contemporaries. It is the kind of flood gates that gets across the openings in very stylish circular segments in cross section. The engineering of it is also very remarkable and the operation thus has been constructed in a very circular and rotating manner. The water gets raised by hydraulics. The raising of water causes from the horizontal sill on the riverbed and as such there is the appearance of a steel and concrete barrier to check the tidal water. This act of rising gets elongated further and the ration continues allowing underspill operations to control the upstream levels and a complete 180 degree rotation for maintenance of the water levels. The barrier makes a shield of 40mm thickness and the gates fill with water when submerged. It then let it go empty as the water emerges from the river in a huge tidal form. The construction id full proof as there are additional four central gated of 61 mtrs long and 10.5 mtrs high; along with two outer gates that are of 31.5mtrs. There are four radial gates of 31,5mtrs long by the riverbanks and are flexible enough to be lowered down. These gates are left opening for the ships and at the same time can be rotated and closed to stop water travelling towards London.

There is no doubt to the fact that this barrier is a very strong step towards the protection of the city from flood.

TECHNICAL UNCERTAINITIES AND INNOVATION

It was Charles Draper who came up with the idea of rotating gates and that is the factor that differentiated Thames Barrier from other contemporary constructions.

The trio of Rendel, Palmer and Tritton were the actual engineers behind the construction of this particular unique barrier. The selection of the site was also very important and as such it was decided that Woolwich will be the most suitable site as it is the relative straightness of the banks. It was also discovered that in this site the underlying river chalk will act as a strong support the barrier. The construction was initiated by Costain/Hollandsche Beton Maatschappij/Tarmac Construction consortium.

The strategically structured things related to the flood defences were made for 11 miles down river and all these equipments were properly raised and strengthened. The amount that was invested in this whole construction was around £534 million (at 2001 prices). Added to this budget was the additional £100 million investment was done specifically for the purpose of river defences. The target was for a span of 1000 years. This was undoubtedly a long term thought and investment. There was a clear understanding of land and water before these declarations are made.

All these assessments now seem very irrelevant as the estimations are failing as per the predictions. The main reasons behind these diversifications are the increasing factors of global warming and the simultaneous rise of the sea level. The barrier was made in order to cope with the projected sea level that will continuously keep on rising till 2030–2050. Not only these are the possibilities, but there are the suspicions that whether the barrier will be able to complete its promised term.

The technical aspects came into being when there was a high tides forecast in the North Sea. The threat was developed more with the declaration that the high river flows at the tidal limit at Teddington weir is the scientifically proven indicator for the measurement of the water levels that was supposed to exceed 4.87 m in central London. The re was the creation and opening of this estuary from the Teddington. At low tide it is a successful effort that can make greater flow rates. With this increase in the rate of flow the further one goes downstream. In the time of upstream flows there gets the act of creating great reservoirs protecting the flood water from rolling down to the city.

POLITICS

The political roles as has been played are very dramatic and worth all discussion. It was in 2005, that there came up a very interesting suggestion that to supersede the Thames Barrier. The target was huge and there was the application for a 16 km (10 mi) long barrier across the Thames Estuary. It was a very long extension from Sheerness in Kent to Southend in Essex was. After the completion of this the whole got exposed to the public for wider speculations and popularity. The political agreements came into being after the disastrous flood of February 1953, when the sea level was raised by 2 metres at Southend.

The disastrous flood covered an area of 64,750 hectares 24,000 houses, and a major set back came into being with 200 major industrial premises, along with a number of 320 kilo-metres of railway. The affects were tremendous over twelve gasworks and two electric power stations that resulted in a heavy loss to the state as a whole. Depressingly enough there were almost 300 people drowned as well as much livestock. The estimations were done about the higher water levels that were supposed to reach 1 in 50 in a year. All these disastrous aspects and the upcoming threats made the governor get more concerned about the consequences. There came up a much stronger political pressure over the government. As such it appointed a departmental committee, the Waverley Committee, to examine the upcoming threats and the relevant solutions to them. As per the report submitted by the committee in 1954, the implementation of a barrier needs to be examined and has to be applied. Initially various sites were suggested, but finally it was Woolwich Reach. As the construction proceeded there came up a serious concern from the Port of London Authority. According to this concern there will be a single unobstructed opening of not less than 1,400 feet in the barrier that was supposed to be constructed. This was a very turning point towards the added complications of the designing strategies. However in 1965, there came up another high surge tide and this time the Waverley Committee recommendation had got nowhere and the whole importance lied on the construction of the barrier as soon as possible.

COMMUNITY INVOLVEMENT

There were heavy sufferances towards the outbreak of these seasonal floods. The more precautions are taken, the quicker the water runs into the sewers and then the rivers, and the faster they rise. The area most affected last summer was Severn Trent. It has been estimated that up to ‘4% of the land in its region is converted to hard surfaces each year’. The floodwater runs off land faster than ever with fewer places to go. There are these assessments made about the queries that whether this critical infrastructure sites have adequate defences. There are many questions coming up towards the success of this particular Thames Barrier. The floods in England are devastating and how far is it possible to make the Thames Barrier secured for the purpose is still a question.

According to the inspections made by the BBC, the flood alerts as has been applied in England and Netherlands are not much effective and fears of storm-driven tidal surges have not materialised. According t the latest assessments and findings these alerts however are saving much life than 1953. It was in that year about 2,000 people in the two countries faced the devastating affects of the flood. In 1953, in a span of a night thousands of people were evacuated in England and surge barriers closed at the Dutch port of Rotterdam. The rush was heavy and the losses were severe. There were great losses faced by England. In Germany and Denmark, several oil platforms were closed off the Norwegian coast and gales are forecast.

These types of scenarios were like lifelong threats to the people of Britain. As a solution to this there was no other option than the application and dependence over the Thames Barrier. The role as has been played by the government way very vital. The only solution that the government could initiate with is the barrier. It was regarded as the’ modern solution’. It was a joint assessment as has been made by the government and the Greater London Council. A barrier was closed without any possibility of failure which was again much supported by public in general. However the acceptability was not granted by the Hydraulic Research Station assessment. As for them it is very complicate business and will not succeed. Against all the opposition the Thames Barrier still stands very firm and is protecting London with all its efforts.

There came up this Barrier Act that holds the responsibility for the barrier within the government. It was thus was readily accepted by the Ministry of Agriculture, Fisheries and Food (MAFF). As it was more concerned about the flooding upon the farming section the approval was due. As consequence to this there was a government grant of 75 per cent that was obtained under MAFF. Added to this was the contribution made by the Ministry of Housing and Local Government, the alternative possibility, would have had difficulty in allocating a grant for anything over 40 per cent of the project budget.

If the flood in London gets neglected than there are the possibility of thousands of homes, shops, factories, businesses and buildings would be affected. The monetary and financial set backs are sure to happen. If all these get activated than there could be such instances that will make London take moths in functioning again. The financial cost of a major flood could be enormous, possibly topping £30,000m without counting the cost in human suffering and potential loss of life.

SCHEDULE DURATION AND URGENCY

After 1953, there were regular assessment being made in order to check the timing and the particular season for the tidal affects. In accordance to the declarations made there were proper evacuations and proper resettlements of the community. The role as played by Thames Barrier here is that it is the protecting shield for the same and there is no such way to make London safer. This barrier needs regular maintenance and that has been well bestowed.

Global warming is the main cause behind all these disasters. Even the Thames Barrier which was supposed to stand or 1000 years is hardly going to meet the deadline. The drastic change in the climate has made things tougher. People are more concerned about the threats and their property than anything else. These are many agencies and corporations who are working for the same. According to the assessment as forwarded by the UK Environment Agency; there supposed to have “extreme danger to life and property” if the Thames Barrier is not maintained well enough.

FINANCIAL, LEGAL AND CONTRACTUAL MATTERS

The financial cost of a major flood has got the topping of an estimated amount of£30,000m without counting the cost in human suffering. This also excludes the potential losses that had happened. The solution was towards the construction of the Thames Barrier. It was a huge construction and as such was very keenly associated with the works of highly sophisticated engineering. As per the estimations the final cost of the flood defences within the Environment Agency’s Thames Region was approximately £535 million. From the contributions of the taxpayers the expenditure was met by 75% of the approved costs and ratepayers were responsible for the remainder.

As undertaken by GLC Department of Public Health Engineering the programme got multifaceted exposure and support from all squares of the population. There were these trio of consultant engineers Rendel,Palmer and Tritton who were in charge of the whole responsibility. All expenditure on which grant aid was claimed was subject to a further detailed check by the engineers and accountants of the Ministry of Agriculture, Fisheries and Food. As a condition of grant aid, all variations over £50,000 had to have prior approval by the ministry.

There was an estimation that states that over 80 staff operate and maintain the Barrier and the associated flood defences. The declarations for any threat could be made before 36 hours in advance and as such the evacuation can happen. However the risks are less due to the Thames Barrier and as such there was hardly any matter to get the threat.

The tidal flood risk to London must be seen in the context of the whole estuary or else the Thames Barrier will be a result of heavier investment losses. The tidal Thames seems to be higher than the Thames Barrier and as such the re needs to be some assumptions made over the sustainability of the Barrier. As when it comes to the planning for the future there comes up the negotiation between the Environment Agency, government, local authorities, environmental organisations and others. The objective that all these organisational units hold is to provide long term-answers on flood risk management in the greater Thames Estuary.

A severe flood in London most of the time affects the central part of the London. The causes are devastating and the damages were made by the river. The attention should also be given to the fresh water and sewer systems and needs to mend them for the disrupt power, gas, telephone and vital data services. This results n heavy financial losses and as such there are many things that needs to be given extra attentions.

CONCLUSION

Sir Hermann Bondi, an eminent mathematician, astronomer and government scientist made a revision over the flood threat in 1966. According to the assessment as forwarded by Professor Bondi, there will be a serious flood in London. He further added that this flood would be

‘A disaster of [a] singular and immense kind’ and that it must not be allowed, particularly since the ability to prevent it existed’.

His idea was for the application of a containerisation that was supposed to be reduced the traffic to the Port of London dramatically. This idea was however not accepted and there came up this mega-structure for the proper and specific measures for the protection of flood. The political awareness led the UK Environment Agency to make the futuristic assessments towards the upcoming threats of the flood in London. According to their assessments, there is sure to be an encounter with an “extreme danger to life and property”. The areas that it specifies are the parts of Norfolk, Suffolk, Kent and Essex. Not only that the UK Environment Agency had issued eight severe flood alerts for the precautionary measures to happen. Added to these alerts there were the declarations made by the Met Office. It announced there is this tremendous gust of up to 145km/h (90mph) that covered the areas of Orkney and Shetland Islands in Scotland.

As a result there was a sufferance of around 500 people. All these people were compelled to spend the night at refuge centres set up at local schools and on the upper floors of their houses. The government was having great concern towards it and the sufferance had no other solution than the Thames Barrier.

REFERENCES

Environment Agency, n.d., http://www.environment-agency.gov.uk/regions/thames/323150/335688/341764/341785/?version=1&lang=_e [retrieved on 17.06.08]

Reliability of the Thames Barrier, n.d., http://books.google.co.uk/books?id=0AU5Ics8LL8C&pg=PA208&dq=bondi+h+1967+thames+barrier&ei=sfs4SLGGIpyUywTI_5XqDw&sig=2eF6CA7we7I5swksvsQVWuPxJUU#PPA199,M1 [retrieved on 17.06.08]

Thames Barrier, n.d., http://www.jasa.net.au/london/thames.htm [retrieved on 17.06.08]

The penalties of ignoring the risks, n.d., http://www.environment-agency.gov.uk/regions/thames/323150/335688/341764/341770/?lang=_e[retrieved on 17.06.08]

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