The Clifton Suspension Bridge Engineering Essay

The Clifton Suspension Bridge is presently an iconic span on the B3129 which spans the 214m broad Avon vale gorge from Clifton Down to Leigh Woods. A span is to be designed to replace the current solution. The new design will take into consideration the map of the span, the construction of the span and the span ‘s strength. Attention will besides be made to the aesthetic belongingss and the cost of the span. The design includes doing the span conform to edifice criterions instructed in the Eurocodes, sing how the span is constructed and besides taking into history the traffic traversing the span.

The design process will dwell of many stages. To originate the design process background research will be completed ; this includes the history of the environing estates plus farther research into the current solution. To originate the design of the span, information is to be collected to help the determination on which type of span is to be used. The conceptual design of the span requires the usage of the collected span information ; each type of span will be analysed by measuring the Bridgess suitableness with mention to a list of cardinal issues. The cardinal issues make up the cardinal design characteristics of a span. ( Chen, Wai-Fah. Duan, Lian. 1999 ) .

Preliminary design employs the decision from the conceptual design stage and evolves a little set of span signifiers into plausible designs with approximative pricing. The concluding span signifier can so be chosen. ( Chen, Wai-Fah. Duan, Lian. 1999 ) . Functional design of the span will be completed following by measuring how the span will be used ; this will be followed so by the structural design of the major constituents. The structural design will follow to the EuroCode ‘s and find the appropriate tonss, material strengths and assorted burden combinations ; so the partial factor method can be used to guarantee the span conforms to both ultimate and serviceability bound province designs. ( Eurocode, 2005, NA to BS EN 1990:2002+A1:2005 )

Following the completion of the structural and functional design of the span, the process for building the span can be drafted along with the deliberate life-cost of the construction. Technical drawings will besides be completed.

2.0 History of Bristol

Pre 1066- The metropolis of Bristol was foremost developed as a colony in the Anglo-Saxon epoch, and was a popular trading town with Ireland and the south West of Wales. Its original name was Brigstowe and was situated between the river Avon and Frome.

1066- The palace normally known now as Castle Park was built after the Norman Conquest. 14th century- Bristol was a popular trading colony and had merchandising links with states in Europe and Iceland.

1700-1800 ‘ Bristol was the 2nd biggest slave trading port in Britain following to Liverpool. A combination of the entire figure of ocean trips made from Bristol and London were estimated to be 4000. Bristol was already a affluent metropolis due its trading but its economic system boomed from the slave trade. The trading of slaves was banned in 1807. ( Klein, S H. 1999 )

1800- In this clip the Clifton country of Bristol had become place to rich merchandisers, who chose to populate a distance off from the docks. Brunel shaped the face of Bristol in a clip where the trade industry was decreasing. His technology expertness ranged from the S.S Great Britain to the Temple Meads Station, which are both on show today.

1831- The Bristol Riots which occurred due to the proposal of the reform measure by the authorities. The proposed rules straight contradicted the old ways of the Whig rules. A reign of panic was commenced for civil and spiritual autonomy. The public violences commenced for three yearss and finally caused the cease of the building of the Clifton Suspension Bridge. ( Eagles J, et Al. 1832 )

1900 ‘s ‘ The aerospace industry was based in Bristol along with the building of the Concord. Currently Rolls Royce Engineers are designed at Filton. Bristol was besides to a great extent bombed during the 2nd universe war, destructing a batch of the architecture. In the 1960 ‘s the innovation of the concrete tower block was invented and was used as a speedy inexpensive replacing. ( Bristol Link )

Presently ‘ Today Bristol is the largest metropolis in the south West of England. Some of its historic architecture is still seeable amount the older parts of Bristol such as Clifton. The town has a really big shopping Centre and in 2008 it ‘s newest edition Cabot ‘s Circus opened. Clifton is presently renowned for its Georgian architecture and the Clifton Suspension Bridge.

3.0 History of the Clifton Suspension Bridge

1753. Alderman Williams Vick of Bristol left ‘1000 in trust for a rock span to be build.

1829. The money had increased to the sum which Vick had estimated the monetary value of the span would be, but his estimation was short of the monetary value of the masonry construction, so a competition was held for the best design with the taking applied scientist at the clip Thomas Telford as the justice.

Figure 3.1 – Brunel ‘s 1829 span proposal across the Avon Valley, reproduced from ( Goff, R.F.D. 1974 )

1830. Thomas Telford rejected all of the designs including the original proposed by Brunel, whom decided to plan the span himself, but deficient financess constrained the legal guardians, and the competition was reopening with Brunel ‘s updated Egyptian themed proposal, shown in figure 3.1, as one of rivals.

1831. Brunel ‘s proposal was excepted when Telford ‘s was dubbed excessively dearly-won, and Brunel was appointed main applied scientist. Site readying began three months subsequently, but was disturbed by deficient financess caused by the disturbed province of the state. The Bristol public violences being grounds of this.

1836. Work eventually commenced and suspension towers were built.

1843. Trustee ‘s financess became dog-tired.

1864. The work was eventually abandoned and the ironwork was sold to cover the ‘30,000 debt of the legal guardians. ( Porter Goff, R.F.D. 1974 )

1859. Thursday 15th September Brunel dies of either a bosom onslaught or a shot, shortly after he was aboard the SS Great Easter ‘s inaugural ocean trip. ( Byrne, Eugene ; Gurr Simon. 2006 )

1860. Members of the Institute of Civil Engineering ( ICE ) formed a company to finish the span as a memorial to Brunel.

1865. The span was completed by applied scientists William Henry Barlow and Sir John Hawkshaw, utilizing Fe from another of Brunel ‘s Bridgess, the Hungerford Bridge which was demolished to do manner for a railroad span. ( Porter Goff, R.F.D. 1974 )

Brunel ‘s design differed from the concluding span which was completed after his decease. One of the chief differences is that three beds of ironss were used alternatively of the two which Brunel predicted. Besides the smooth rock towers were left as unsmooth stoned towers and the Egyptian styled ornament which can be seen on top of the towers, in illustration figure 3.2, were non added. ( Byrne, Eugene ; Gurr Simon. 2006 )

Figure 3.2- Brunel ‘s Second proposal in 1831, figure reproduced from ( Porter Goff, R.F.D. 1974 ) .

4.0 Types of Bridges

4.1 Beam Bridge

A beam span consists of a beam which is merely supported at each terminal. The beam span is the earliest signifier of span and was originally constructed by puting a log across the span. In modern times the beam is made utilizing strengthened concrete which has an economical span of 8′-12 ‘ ( 2.5m -3.5m ) . Alternatively a rolled I beam is used with an economical span of 20 ‘ ‘ 50 ‘ ( 6m-15m ) , ( Bangash, M, Y, H. 1999 ) .

Figure 4.3.1 ‘ A uninterrupted beam span without and with cardinal support sourced from ( Pritchard, B. 1992 )

Beam Bridgess are used to transport a assortment of tonss including vehicles, walkers and on juncture are boats, and can easy be adapted for different tonss by intensifying the beam. They are normally used to transport tonss over expresswaies, by positioning a column in the cardinal reserve as a support ; this is a uninterrupted span beam. An illustration of a individual span and uninterrupted span beam span is shown in figure 4.1.1.

The construction of the beam span is really simple ; the beam transfers the applied burden through bending and shearing to the next columns, so through to the foundations.

As stated the beams are most efficient in comparatively short spans. This is because as the span increases the deepness of the beam has to besides increase ; hence big spans require really big deepnesss of solid stuff increasing the monetary value and weight.

The beam span is by and large aesthetically unpleasing. They are by and large inelegant with a big deepness doing them visually unappealing. The design can be altered to increase its entreaty by planing the parapets to make shadows on the chief construction, therefore doing the construction appear dilutant. Besides shown in figure 4.1.1 the visual aspect can be improved adding a haunch to cut down the volume to less structurally reliant countries, i.e. mid span ; this besides makes the construction more efficient ( Gottermoeller, F. 1998 ) .

4.2 Cantilever Bridge

A cantilever span consists of a beam which is either resisted by tortuosity at the support as demonstrated in figure 4.2.1 or cantilevered around a support with an opposing construction as shown in figure 4.2.2. The cantilever span has an economical span of 600 ‘ to 1575 ‘ ( Bangash M. Y. H. 1999 ) . Small cantilever Bridgess normally consists of a simple spanning beam nevertheless for big spans a trust construction or pre stressed concrete box girder is used to organize cardinal construction ; good illustrations of these are the Commondore Barry Bridge shown in figure 4.2.2 and the Pierre Pflimlin Bridge.

Figure 4.2.1- An illustration of a cantilever span sourced from ( Johnson, J, B. Et Al. 2008 )

Figure 4.2.2 ‘ The Commondore Barry span, an illustration of a ego cantering span sourced from ( Richman, Steven M. 2005 )

The span design can be really strong and stable, therefore doing it suited for both roads and railroads traffic. Ideally the span should be self counter weighting, utilizing an grounding span to counterpoise the cantilevered span.

The building of a ego anchored cantilever span can be simple by spread outing outwards from the span support. This makes it possible to build over H2O where signifier work is non accomplishable. For a three span span two columns can be constructed at a one-fourth and three one-fourth the span, and so the two Bridgess can be extended to link at midspan. Cantilever Bridgess can by and large be rather expensive due to the sum of high sum stuff ( Bangash, M, Y, H. 1999 ) .

4.3 Arch Bridges

Arch Bridges rely on the compaction of the structural stuffs ; hence the usage of concrete and masonry are normally employed as they have much higher compaction strengths in comparing to their tensile strength ; a demonstrated arch span is shown in figure 4.3.1. Arch Bridgess were predominately used as prosaic paseos and railroad lines as they produce really stiff constructions ; ideal for rail lines.

The arch operates by reassigning the perpendicular burden into horizontal and perpendicular emphasiss to the supports ; finally doing no bending minutes through the beam. Most Bridgess span a little 5 ‘ -12 ‘ ( Bangash, M, Y, H. 1999 ) , and were normally used in medieval times where composite Fe engineering had non yet flourished ( Moore, Fuller. 1999 ) . The tallness to cross ratio of the arch will impact the stableness of the construction ; if the construction is excessively high the sides could be prone to buckling and if the arch is excessively shallow the bricks may neglect in tenseness or shear. A reverse with arches is failure under bizarre point tonss thereby doing uneven distribution of the burden.

Figure 4.3.1- An illustration of a masonry arch span ( Johnson, J, and B. 2008 )

An arch span is constructed with assistance of false work ; this makes an condescending construction unsuitable for state of affairss where the topography situated below the Bridgess span is unaccessible. In modern times the arch has been constructed utilizing a truss arch construction ; leting longer spans to be reached with minimum stuffs.

Masonry arch Bridgess are by and large aesthetically delighting and are normally decorated, they are a simple construction and high sums of stuff mass is situated where observer expects ; hence bettering the Bridgess visual aspect ( Gottermoeller, Frederick. 1998 ) .

4.4 Suspension Bridges

Suspension Bridgess designs are by and large used to cross long distances where limited infinite or foundational stableness disallows the usage of false work. Primary suspension Bridgess were constructed of rope for worlds to traverse vales.

A suspension span consists of a deck which is supported vertically in intervals by suspension hangers. The hangers are so attached to a suspension overseas telegram which is supported vertically by towers and horizontally by ground tackles ; this is demonstrated in figure 4.4.1. The suspension should of course organize a catenary curve ( Moore, Fuller. 1999 ) . The construction is most efficient over about 1595 ‘ ‘ 4200 ‘ ( Bangash, M, Y, H. 1999 ) .

Structural effort can happen to the span when fliting air current burden or oscillated imposed burden is applied ( Simiu A. 1978 ) . A instance survey of utmost oscillation is the Tacoma Narrows Bridge ( Galloping Gertie ) which collapsed during a minor storm. The storm caused the span deck to quickly displace laterally and produced hovering perpendicular ripplings along the Bridgess length enforcing residuary impulse tonss in the rods, finally doing structural failure. Post Galloping Gertie solid girders have been used to oppose the burden from air current.

Similar to the cantilever span, the suspension span can be constructed without any signifier work ( Moore, Fuller. 1999 ) .

A longitudinal truss can be used longitudinally along the deck to curtail the deformation and administer the concentrated emphasis on the overseas telegram ; hence curtailing the motion of the overseas telegram and deck. If there is no stiffening truss construction, the overseas telegram is free to accomplish the place dictated by the applied burden ( Steinman, Dr D.B. 1929 ) .

Figure 4.4.1- An illustration of a two hinged suspension span ( Chen, W. Et Al. 1999 )

Recently steel box girders have been used to organize the deck. When this was foremost introduced it caused an aerodynamic job demonstrated by the Forth span, the issue was resolved by streamlining the deck which was subsequently introduced on the first Severn crossing ( Roberts, Sir Gilbert. 1968-1969 ) .

Figure 4.4.2 – The desertion at UDL burden on either side of the span and a Point burden one one-fourth of the manner in. This is sourced from ( Kumar, Arvind. 2001 )

Analysis of the span has shown in figure 4.4.2 shows how the construction deforms under a uniformly distributed burden and how it deforms under a point burden.

4.5 Truss

A truss is a construction formed utilizing triangular geometry. The trigon articulations do non revolve when an induced force is applied ; opposed to a rectangle where a shearing action can easy happen. In a general construction perpendicular elements are in compaction and horizontal members are in tenseness as shown in figure 4.5.1. A good illustration of this is shown in a vulture ‘s wing which construction forms a tetrahedron form. Truss construction forms a really stiff construction due to their inflexibleness. This stiffness means it is really common for long span trains.

The construction is really stiff due to the little length of each member and the geometry of the construction ( Moore, Fuller. 1999 ) . A truss span by and large has an economical span of 100′-300 ‘ ; as the span increases the truss tallness has to be increased which increases the cost ( Bangash, M, Y, H. 1999 ) .

Figure 4.5.1-The compaction and tenseness of members in a truss construction

A truss construction has to be constructed utilizing false work or floated in if located over H2O, as shown in figure 4.5.2. This makes it hard to build in certain environments such as gorges or when the span is situated high above sea degree.

Truss constructions are by and large aesthetically unpleased, this is because they are by and large really deep complicated constructions and frequently they are made utilizing treated metal which does non usually suit in with the environment ( Gottermoeller, Frederick. 1998 ) .

Figure 4.5.2- The floated truss subdivision of the Newburgh-Beacon Bridge ( Chen, W. Et Al. 1999 )

4.6 Cable-stayed Bridges

Cable-stayed Bridgess decks are supported by overseas telegrams which are straight attached to a tower. The three fluctuations of overseas telegram stay Bridgess are shown in figure 4.6.2. The harp type cable-stayed span has all the overseas telegrams running parallel to one another, and is deemed to be the most aesthetically delighting. It besides allows an early start to building the box girder deck since the overseas telegrams initiate at a lower tallness ; hence building can get down before the completion of the towers. Large tensenesss are required to back up the deck due to the lower overseas telegrams running about perpendicular to the way of span, doing inefficiency of the overall construction.

An illustration of a overseas telegram stay span is the overseas telegram stay bridge traversing the Rio Ebro in Spain. An illustration is shown in figure 4.6.1. The span spans 137.12m across the river and has a deck breadth of 28.90m. The column tallness is 58.80m and the span is a multi span harp type. ( Bangash, M, Y, H. 1999 ) .

Figure 4.6.1- Cable-stayed span traversing the Rio Ebro, Spain sourced from ( Walther, R. et Al. 1999 ) .

The radial cable-stayed span overseas telegrams are places every bit perpendicular as operable hence bring forthing one of the most efficient overseas telegram stay signifiers. However the radial solution is seldom used in pattern due to the complex agreement of the overseas telegrams within the saddle. The agreement can look awkward if the design is non successfully implemented.

The fan agreement is most common due to its efficiency and easiness of building. Compared with the radial solution it is easier to plan and still holds the aesthetic qualities of the harp. ( Chen, W. Et Al. 1999 )

The overseas telegram stay span differs from the suspension span in two chief ways. The first is that the deck is attached straight to the towers, and the 2nd is that the hanger overseas telegrams are non perpendicular. Cable stay Bridgess are the most efficient over really long spans when a repeated tower-deck unit is used. The overseas telegram stay has an advantage over really long distances as the overseas telegram stay span can be used over multiple spans where a suspension span ideally can merely be a one or three span.

The deck of a overseas telegram stay span has to be comparatively thick to defy the horizontal burden applied by the angle of the overseas telegrams. The extra thickness of the deck and tallness of the towers decreases the affordability of cable-stayed Bridgess in urban countries. Another advantage of the cable-stayed span is its increased rigidness, therefore leting it to transport rail traffic, where a suspension span would non be stiff plenty. ( Walther, R. et Al. 1999 ) .

Figure 4.6.2- Three types of overseas telegram stay Bridgess ( Chen, W. 1999 )

Cable stay Bridgess are normally used for prosaic paseos due to their aesthetic qualities. They are an elegant construction with a thin deck and really simple ; they are besides a uninterrupted construction ( Gottermoeller, Frederick. 1998 ) .

5.0 The Clifton Suspension Bridge

5.1 Function

The Clifton Suspension Bridge was designed by Isambard Kingdom Brunel and completed in 1864. The span spans 214m across the Avon Valley Gorge from Clifton to Leigh forests as shown in figure 5.1.1.

Figure 5.1.1-Topography of the place of Clifton Suspension Bridge, reproduced from ( Porter Goff, R.F.D. 1974 )

The towers are 26.2m high and the Centre to center breadth of the concatenation is 6.1m. There are two vehicle lanes and two prosaic waies, which are often used as a sing topographic point along the Avon gorge. There are about 10,000 autos traversing per twenty-four hours with a gross vehicle weight bound of four dozenss. The toll for the span is presently 50p ( 27/11/09 ) . Bing an historic span, the construction requires changeless services which the tolls financess support. The velocity bound on the span is presently 15mph and the weight bound is controlled utilizing a modern weight beam ( Mitchell-Baker, D. Et al 1988 ) . The span was designed to originally take the weight of Equus caballuss and passenger cars. The site location was chosen because of its short and flat span.

5.2 Structure

The span takes the signifier of a convention suspension span. This signifier was ambitious at the clip of design and if it was completed on agenda it would hold been the longest suspension span in the universe. The suspension span was a suited pick for two chief grounds. The first ground is that the tallness between the deck and the river below is 75m and to build a tower would be expensive. It besides would hold been expensive to build any signifier work. A suspension span can be constructed without the assistance of signifier work and Brunel ‘s design did non necessitate a tower compared with Telford proposal which included two Gothics styled towers ( Moore, Fuller. 1999 ) . The 2nd ground is that the strength of the environing topography allowed the being of ground tackles. In state of affairss where a suspension span would be suited, the status of the land is unsuitable for bearing the force per unit area from the overseas telegrams. One of the disadvantage of utilizing a suspension span on the site is that it can merely be a individual span. The

ground tackles have to take the entire tenseness of the concatenation compared with a three span span where the deck on the side span acts as a counter weight, alleviating tenseness in the ground tackle.

The construction is formed chiefly of a long concatenation, similar to a motorcycle concatenation, two towers and the span deck. As it is shown in figure 5.2.2 the concatenation is formed of three sub-layers on each side, each bed dwelling of an jumping 10 and 11 level wrought Fe bars. By increasing the sum of ironss, the construction becomes less reliant on each person concatenation ; hence failure of a concatenation should non take to fall in. The level wrought Fe bars were designed to be every bit long as operable. The long bars decrease the entire weight of the ironss by cut downing the sum of heavy articulations.


Figure 5.2.1 -The bottom of Clifton Suspension Bridge, courtesy of The Clifton Suspension Bridge Trust.

The dip to cross ration of the ironss contribute to the efficiency of the construction. High span to depth ratios do larger concatenation tensenesss because the way of the concatenation reacts about perpendicular to the burden way, making an inefficient construction. Low span to depth ratios do a more efficient concatenation curve but the highs of the towers are accordingly increased which increases the entire cost, besides making an inefficient construction. The most effectual span to depth ratio is about 1:10 which is what was adopted by Brunel for the span. This is an betterment to the 1:13.5 ratio which Telford antecedently adopted on the Menai span. The chief catenary ironss are non attached straight to the deck at maximal dip ; this is done to let the chief deck to hover freely in the air current without seting inordinate strain on the ironss ( Pugsley, Sir A. 1976 ) , ( Porter G. 1974 ) .

Hanging at 8ft intervals are the shaped Fe rods, which transfer the burden onto the concatenation. The array of rods is designed to oppose prostration if a individual rod should neglect. The rods are attached slackly between the concatenation and longitudinal girder, see figure 5 ; this allows motion which decreases the opportunity of failure from span motion. This so imposes a perpendicular downward force onto the towers and tenseness along the concatenation and in the ground tackles.

The longitudinal girder as shown in figure 5.2.2, is a uninterrupted stiffened I beam. The girder is 3ft deep and connects the cross girder to the rods. The original design proposed by Brunel used a timber lattice girder with a matching stiffness, but by the clip of the Bridgess building the lumber lattice was replaced by an Fe plated girder. The girder takes the emphasis applied to a individual articulation on the concatenation and traverses it along the longitudinal length of the concatenation.

As illustrated in figure 5.2.1, a truss construction is adopted for the cross girders. The truss construction is a really strong and efficient construction along the length. The shallow deepness allows thin strips to organize the trusses without clasping. The place of the cross girder is shown in figure 5.

The cross girders are braced horizontally utilizing thin Fe strips to respond against air current burden. The quadrangle form deforms under burden by rotary motion at the articulations. The brace forms a triangular molded construction ; distortion in the triangular molded construction occurs by flexing of each member, therefore increasing the elements stiffness.

Live tonss are transferred onto the lumber beams which span between each cross girder ; using a perpendicular burden and doing a bending minute in the girder. The lumber decking was chosen because it was light and suitably strong ; it besides allows easy accessible fixs. A shaped Fe adorning frame was added by Barlow and Hawkshaw to increase rigidness.

The saddles are situated on top of the towers. The saddles allow sidelong motion of the ironss. Lateral motion occurs due to temperature alterations or unsymmetrical burden. The saddles besides allow the perpendicular emphasis to be reduced in the rock tower by increasing the contact country, understating the hazard of oppressing the rock.

The ground tackles are 17m below the land and the ironss are spread into a chamber to make a stable foundation. The spreading of the concatenation allows the tenseness to be opposed by the compaction of the drop, non entirely trusting on the clash. The advantage of this is that the strength of the ground tackles increases ; it besides takes advantage of the strong limestone foundation. ( Pugsley, A. 1976. )


The constructions weight bound for vehicles is presently four dozenss. This weight bound was introduced about 50 old ages ago when applied scientists decided that the big tonss and weariness could take to fall in. The sum of vehicles on the span at one clip is controlled by the toll booths. This is done to cut down the entire burden on the span at any minute.

Brunel designed the span to defy an adventitious burden of 100lbf/sq.ft which is about equal to 4.7 KPa of force per unit area ( Porter G, R.F.D. 1974 ) . . This is simular to the unrecorded burden which is adopted on modern Bridgess with similar spans ( Bangash, M, Y, H. 1999 )


After planing the span, the foundations and abutments were the first elements to be constructed. Then the towers were the following thing to be constructed. The ironss were pulled across by rope and so the deck was attached to the concatenation.


Between 1864 and 1953 the lumber decking had been replaced three times and the ironwork had been treated twice and at the terminal of this period was still in good status. Two suspender rods had failed in a terrible storm in 1877 and three more had failed in 1887. Both occasions the exact cause of the failure is still non convincingly known.

In 1861 a 6 metric ton vehicle weight bound was appointed to the span. The size and weight of vehicles was continuously increasing and applied scientists were concerned with the Bridgess construction. It was based on the theory that repeated lading on metal causes its hempen construction to go crystallite.

In 1918 one every 10 bolts from the rods were removed for proving, and they were all found to be of equal strength though some cleft appeared ; these clefts were likely to happen from hammering.

The drainage of the span had caused serious corrosion to anchor degree ironss. In 1925 an excess nexus was added to the ironss but there were still concerns for the ground tackles status. To get the better of this concern concrete was poured to a deepness of above 9ft above the ground tackle.

In 1953 the duty of the span was passed to the trusses and the national heritage. The point burden of wheels was known to be more detrimental to the deck than to the construction as a whole, doing the deck to be once more in a terrible status. The weight bound was so changed from 6 ton bound to 2.5 ton axle weight and 4 ton vehicle weight. ( Mitchell-Baker, D. . Cullimore, M. S. G. 1988 )

In 2009 a prosaic noticed a serious cleft in one of the suspension rods and the closing of the span followed. Impermanent supports were put in topographic point while the rod was replaced. A twelvemonth earlier work to better the sealing, drainage and new route surface was completed. This would diminish the sum of corrosion of the Fe work. ( BBC News. 2009 )


The span is really aesthetically delighting, it has few single elements, and each component is similar in map. The girders are really thin and it has a uninterrupted span which besides makes it more appealing to people, most people would hold the span is beautiful. The form of the construction besides reflects the force applied to it, being dilutant in the center and thicker as it gets towards the borders where the greater minutes would happen. The span besides has a bold and dramatic lineation when viewed from along the vale ( Gottermoeller, F. 1998 ) . The towers are curved so that they appear tall from below, organizing a bold construction. The towers are besides in good proportions compared with the immediate surrounding and harmonious in three dimensions. The span is constructed utilizing locally sourced stuffs, incorporating the construction into the environment. ( Chen, W et Al. 1999 ) . The span is 3ft higher on the Clifton side. This is done to halt the semblance that the span deck is falling towards the drop.