Civil Engineering Structures in North Wales Paul Jones Bsc (Hons) Construction Management

Aims and Objectives Aims. The aim of this unit is for you to gain an introduction to the world of civil engineering. You will also investigate the factors that constrain civil engineering projects and gain an understanding of the function of a civil engineer. Objectives. Understand the economics and lifecycle issues associated. Recognise plant used in Civil Engineering projects. Identify different methods used in civil engineering activities

Employment History Eastlands Stadium in Manchester. A55 at Rhuallt Hill.

Military Bridges The Two types of Bridges built by the British Army throughout the world. The extra wide Bailey Bridge pictured above, with the now more common Medium Girder Bridge pictured below.

Civil Engineering Structure Civil Engineering is the part of the Construction Industry associated with the planning, construction and maintenance of big construction projects such as Roads, Railway lines, Bridges, Canals, Docks, Dams and Tunnels. A structure can be defined as ‘something that has been constructed’. So today we will look at Civil Engineering structures that have been constructed in North Wales. The A55 expressway. The Conway Tunnel The Bridges across the Menai Straits.

The A55 Expressway The first major roads in North Wales were constructed by Thomas Telford, and this included two suspension bridges, one crossing the Menai Straits and the other the Conwy Estuary. Why is it important to have a good road network? It allows goods, services and people to travel easily across the country, this in turn is good for the local economy. What was the problem with the roads built by Telford? They were never meant to take the large volumes of traffic we know today.

Modern Road Construction Modern Roads require a pavement that can perform a number of tasks. 1. Take the weight of the traffic. 2. Provide a safe surface, to give a smooth ride, with good braking. 3. Provide a surface that will drain water away quickly

The A55 Expressway What is the biggest Industry in North Wales? Tourism, every year many people come to North Wales on Holiday. This industry relies heavily on Civil Engineering putting a structure in place to allow people to travel easily and safely.

The A55 Expressway The Modern Expressway has created a fast dual carriageway linking the port of Holyhead to Chester, reducing travel times and traffic congestion in towns across North Wales. But one town in Particular had more traffic problems than any other.

The A55 Expressway One of the worst spots for Traffic congestion in North Wales was the town of Conwy. Anybody having to travel through North Wales had to drive through this Historical Town. As the amount of traffic increased and the size of Heavy Goods Vehicles increased, the problem got worse, and was described as the worst bottleneck in Wales. This problem took Engineers 50 years to find a solution to the problem

The Conwy Tunnel Trying to fine a solution to crossing the River Conwy, threw up a number of problems. One of these being the Geology of the area. However to protect the Historical town of Conway, and offer some relief to the local people from the traffic a solution had to be found, so what are the options ?

The Conwy Tunnel The two main options available for engineers were either. 1. Build a bridge (There are already three bridges across the River) 2.Dig a Tunnel.(Traditional method for this would be a tunnel boring machine)

The Conwy Tunnel The solution was to build the first immersed tube tunnel in this country These tunnels were built on dry land, in an area that is now the Conwy Marina. In the Photograph we can see six tubes have been constructed. These were then floated out into the river and sunk into a channel cut into the river bed.

The Conwy Tunnel This photograph shows us the route taken by the tunnel. On either side of the river bank the tunnel approaches are being constructed, which will eventually bring the A55 under the River Conwy In the bottom left hand corner we can see the tubes ready to be floated out into the river.

The Conwy Tunnel Once all the immersed tubes had been constructed they were floated out into the river. Each of these tubes weighed in at 30,000 tonnes, and were guided into position by a pontoons. The sinking of the tubes took place during periods of low tide.

The Conwy Tunnel A trench had been cut into the bed of the river. The pontoons then had the job of carrying each section over the top of the trench, and then sinking each tube into position. Ballast water tanks in each section were used, to sink or float each tube.

The Conwy Tunnel As well as building the tunnel, there was also around 6km of dual carriageway to be constructed. Bridges, underpasses and the main North Wales Railway line to contend with, made this a huge Civil Engineering project.

The Conwy Tunnel

The Menai Suspension Bridge Built by Thomas Telford in 1819, was the World’s first iron built suspension bridge. This also linked the Island of Anglesey with the mainland. Thomas Telford had been given the task of improving the road network. (This was the old A5) This bridge dramatically reduced the travelling time between Holyhead and London by 9 hours.

The Menai Suspension Bridge Why do you think the bridge had to be built high above the water? One of the requirements for this bridge, was that it had to have a 100 foot clearance, for sailing ships to pass underneath. The only way that Telford could think of to do this was to suspend chains across the river, and then fix the road deck to this.

The Menai Suspension Bridge The chains are both anchored into the rock on both sides of the river. Remember in 1819 when this bridge was built, there were no cranes, everything had to be lifted by hand. The chains were then lifted over the two main support towers. From this the road deck would then be added.

The Menai Suspension Bridge The benefits of having a suspension bridge can be seen here from this photo. It is able to give a huge clearance underneath the road deck. Arches, like the ones on the right, are limited to the distance they can span.

The Menai Suspension Bridge As good as the bridge was, it had one limiting factor. It could only take road traffic. As the Industrial Revolution gathered pace, there was more demand for a railway link to Holyhead.

The Tubular Bridge In 1850 Robert Stephenson built the Tubular Britannia Bridge. Anglesey now had a railway line. People and goods could now travel to the port of Holyhead quicker than ever before.

The Tubular Bridge Both of these bridges then remained until 1970, when the tubular bridge caught fire, and was completely destroyed. However this disaster enabled engineers to come with a very good solution. To re instate the railway line, and improve the road network system to Holyhead.

The Britannia Bridge They built a bridge that could carry both Road Traffic and Railway stock. Metal arches were added to the underside of the bridge to strengthen it. And a road deck added over the top of the Railway Track.

The Britannia Bridge With the Britannia bridge being re built, and the completion of the Conwy tunnel, the A55 expressway has virtually been completed. Allowing motorists a safe, comfortable and speedy journey through North Wales. So what do you think will happen in the future? Will we need to upgrade this system?

The Britannia Bridge As well as talk of upgrading the Britannia Bridge to a dual carriageway. There is also talk of an Irish Sea Tunnel. One of the proposed routes would link Holyhead to Dublin.