“…This structure presented highly complex technical challenges to the engineer, concealed by the apparent effortlessness of the resulting form…”

“…Self anchored suspension bridges are rare, but with a span of 170 metres and a markedly curved plan alignment this one is both daring and unique…”

This design breaks new ground. Self anchored suspension bridges are rare, but with a span of 170 metres and a markedly curved plan alignment this one is both daring and unique. The fluid forms of the curved shape and varying cross section of the steel box girder deck have clearly derived from an integrated 3D analysis of the structural and visual influences, and the result is a very pleasing and harmonious whole.

This structure presented highly complex technical challenges to the engineer, concealed by the apparent effortlessness of the resulting form. Large compression forces arise in the bridge deck due to the inwards pull of the main cable, and the eccentric hanger support along one edge of the deck acts with the plan curvature of cable and deck to control the horizontal bending effects. The bifurcation at each end neatly deals with the desire lines of the approaching paths as well as providing structural stability to the whole system.

The varying depth of the steel box girder responds to its structural needs and also helps to avoid aerodynamic problems. Tuned mass dampers are provided to control the synchronous lateral excitation problems experienced by the London Millennium Bridge.

Self anchored suspension bridges generally require temporary props to support the deck before the main cables can be attached. The solution in this case was an ingenious combination of temporary stays and props, with the entire 187m long deck, complete with bifurcations at the ends, being lifted into place as a single piece using two floating cranes.

“…the Achray Bridge suits its site well…It is an excellent example of the structural engineer's art…”

This pedestrian bridge crossing is the result of dedicated research to develop an extremely economic and sustainable solution for small footbridges in remote rural locations. It is also probably the forerunner of a significant rural industry.

The stress-laminated arched-form timber deck is an efficient, easy to build structural system. Rough sawn softwood sections 2m long placed side by side are stressed together transversely using high strength steel or carbon fibre bars. It is a logical and appropriate development of a well established technology, and with careful site selection needs only minimal abutments.

The Achray Bridge suits its site well, and the designers have sought to capture the "genius loci" of the landscape and enhance the woodland setting. It is an excellent example of the structural engineer's art. At only about £800 per square metre, this design is a very economic solution, one with a very small carbon footprint.

“…clearly designed to match the contractor's tight programme and facilitate rapid erection, this is an excellent example of the "no frills" design and build engineering approach…”

The need to design and deliver a low cost but eye-catching footbridge across a busy highway in just eight months drove the engineers to produce this pragmatic cable stayed solution. Clearly designed to match the contractor's tight programme and facilitate rapid erection, this is an excellent example of the "no frills" design and build engineering approach.

The 110 metre long, three metre wide structure is unusually high, spanning at 12 metres, above the carriageways below. This makes the overall proportions difficult to balance. The designer's solution results in a very slender and narrow A-frame mast structure. The mast legs, protected against vehicle collision by large concrete bases, feature simple bolted flange joints to speed erection.

As the footbridge provides the main access for pedestrians to the Exeter Chiefs' new rugby stadium, the design of the slender deck required special treatment for the potential dynamic effects induced by large crowds.

“…here, the structural engineering is all about subtlety and restraint instead of drama and excess, and it is all the more successful for it…”

This little gem of a footbridge appears to float effortlessly just above the water as it snakes its way sinuously across a lake in London's famous Kew Gardens. The minimalist design intentionally hides the primary structure from view to all but the ducks passing underneath, but it is precisely this invisibility that so beguiles the observer. Here, the structural engineering is all about subtlety and restraint instead of drama and excess, and it is all the more successful for it. The structural solution derives from the architect's desire for some very fine and well considered details. This is a delightful example of structural simplicity at its best, the result of what is left when nothing else can be taken away.

The balustrades are closely spaced bronze uprights with no handrail, no infill mesh and no embellishment whatsoever. To achieve this apparent effortlessness the engineer needed to specify tight tolerances, since there is no scope for misalignment