Al Haddington to Dunbar Expressway r- lo #(X Balfour Beany ^39^ Larl BrO %JJ Clvil Engineering 3 54 Design & Construction the use of a flexible composite pavement, where the lower base comprises cement The route commences at the existing Abbotsview bound materials Interchange near Haddington, where the the need to maintain a "flowing" vertical addition of slip roads on the east side of the alignment which reflects the surrounding junction completes the diamond interchange. It landform continues alongside the existing Al for 6l<m provision of eight detention basins to before deviating to the south at Pencraig Hill control the flow of surface water run-off and crossing the River Tyne valley on a 217m into the adjacent watercourses three-span bridge. The route continues parallel and to the south of the East Coast Main Line There are 1 2 principal structures: a(ns ^ before rejoining the existing Al at a new roundabout at Thistly Cross. River Tyne Bridge; a three-span, post- tensioned concrete box girder bridge, Notable design features of this scheme include: supported on splayed leg piers two overbridges; both three-span the extensive use of "false cuttings" to steel/concrete composite superstructures reduce the visual and noise intrusion of the six reinforced concrete box underpasses road on the surrounding environment three reinforced concrete segmental the use of an earthworks bund alongside arches with reinforced soil headwalls and the railway line wingwalls a rationalised earthworks design aimed at 8^ obtaining an on-site cut/fill balance while Within each structure type, a consistency of form taking advantage of the available rock and and finish was adopted to give the appearance maximising its re-use in the works of a family of structures. River Tyne Bridge Extensive consultations were held with interested parties including the Royal Fine Art Commission and The River Tyne Bridge is the largest structure on the East Lothian Council. As a result the design concept project and is one of the largest and most complex for the bridge in terms of configuration, span bridges procured by the Scottish Executive. The arrangement and proportions, and much of the bridge is set in the Tyne Valley, which is one of the details and complex geometry, were fixed by the most valued landscapes in East Lothian and is Carl Bro design team and embodied in the officially designated as an Area of Great contractual requirement. This presented the Balfour Landscape Value, a Nature Conservation Area and Beatty and Scott Wilson team with a significant 3linkbon a Scottish Wildlife Trust Wildlife Area. In addition planning, design and construction challenge. The there is a public right of way on the river walkway complex geometry of the structure (curved highway from East Linton to Holies Castle. In response to the alignment and sloping deck sides), combined with sensitive setting the Carl Bro bridge design team the inclined piers and access constraints within the and the Scottish Executive produced a design for a river valley, meant that the temporary works landmark structure which reflected the asymmetric required to support the bridge were complex and valley form and provided a bold expression of extensive. A 3D computer model of the structure function whilst minimising impact on the valley. was developed to aid construction. X3 Jerusalei h / The bridge was cxjnstructed on scaffolding placed across Landscaping / Environment the whole valley, partly supported on a temporary bridge over the River Tyne (the largest scaffolding used As a matter of policy, the Scottish Executive in Scotland to dote). The design takes advantage of the seeks to minimise the landscape impact of decision to adopt scaffolding and uses slender webs to road schemes by integrating the road with its minimise the self weight and cross section to be stressed. surroundings. The deck is stressed by post-tensioned tendons (16 in the main span and 20 in each of the side spans). Each Landscape considerations have been an tendon consists of highly stressed steel strands weighing integral part of the design and approximately 1 Of. Stressing was carried out in multiple implementation of the scheme. 450,000 new stages interleaved with complex staged lowering of the trees and shrubs have been planted and falsework. 1 50,000 square metres have been sown with wild flower seeds. The arrangement of piers and main span of the bridge results in high stresses in both the deck and pier legs, resulting in the use of high strength concrete and Ironside Farrar, landscape consultant to the substantial reinforcement. The east pier is founded Scottish Executive, helped develop a route that directly onto rock, while at the west pier rock is at a depth balanced landscape, environmental and of some 15m and a grid of 60 small diameter piles engineering considerations. (both vertical and inclined) was installed beneath each leg. They carried out an Environmental Assessment through which the Scottish Executive committed The completed bridge solution Is a bold enhancement to to specific measures to reduce the impact of the River Tyne Valley and has successfully delivered all the road, such as creating new landforms to the objectives identified at the consultation stage and is screen neighbouring properties and extensive a testament to the combined skills and teamwork of all planting to integrate the road into the parties. landscape. orharn 66 68 This drawing has been reproduced from the Ordance Survey Map with Sanction of the Controller of HM. Stationery Office Crown Copyright reserved. West B^^rns^__ ' jNorteltohn .l ^Y Hedderwick Burn ^ North Belton Biel Water Broor^h^Jir^^^ Balfour Beatty employed Gillespies as During the development of the scheme landscape consultant to develop the design for extensive surveys were undertaken for implementation. Hedges and hedgerow trees protected species such as badgers, otters and have been planted along many of the bats, and for mapping of plants and habitats. boundary fences. Landforms and belts of Information from the surveys was used to screen planting have been introduced to screen design measures to protect badgers and otters neighbouring properties such as at and to protect or create diverse habitats. Abbotsview, Sandy's Mill and Overhailes. Broad belts of new woodland planting have Measures taken during construction included been introduced to reflect the pattern of the the relocation of badgers from setts directly existing woodland and shelterbelts, affected by the route and the careful checking Meiklerig particularly between the new Al and the old of trees and hedges for bats and birds prior to road. felling and site clearance. The landform around the new River Tyne Long-term measures include a number of Bridge has been carefully shaped to help mammal tunnels allowing badgers and other integrate the bridge into the river valley and small mammals to pass beneath the road along extensive planting was carried out to extend former routes that have been severed by the the existing riverside woodland up to the road. construction. Extensive lengths of specially 'ressmenn^n Afood designed fencing will be used to prevent the To enhance biodiversity and maintain a natural ) mammals crossing on the road and to guide appearance, all the trees and shrub species, them to the pipes. with a few exceptions, are Scottish native, and almost all have been grown from seed collected in Scotland. As well as integrating the road into the landscape, the planting and seeding proposals are designed to replace lost habitat and Wildlife & Habitats augment existing habitats. Planting includes native woodland, hedges, native scrub and Extensive measures have been undertaken to wild flower grasslands. It is anticipated that reduce the impact of the road on wildlife and this will greatly enhance biodiversity in the habitats. local area. The Project During 1 997-98 the junctions at Monksmuir and Phantassie were deleted from the scheme in Following the Routes South of Edinburgh Study order to reduce the environmental impact and in 1 990 the decision was taken by the Scottish the cost of the scheme. The concept of the "Al Expressway" emerged at this stage. In 1999 Executive to upgrade the Al to near motorway the Strategic Roads Review carried out by the standard as far as Dunbar. The Scottish Scottish Executive confirmed the Expressway as Executive appointed Carl Bro as consultant to the preferred scheme. In 2001 the statutory prepare proposals to upgrade the Al from processes were complete and Carl Bro Tranent to Haddington and from Haddington continued the development of the scheme in to Dunbar. sufficient detail to allow a competition to take place for the Design, Construction and A preferred route for Haddington to Dunbar Maintenance of the Al Expressway. The was published in 1 992. Following a period of opening of the Al Expressway represents one further consultation and scheme development a of the last components of the commitment made Public Local Inquiry was held into the proposals in 1990 and will provide considerable benefits in 1 997. for road users and local communities. Procurement These constraints allowed the tenderers freedom to develop proposals which suited A competition was held for the Design, their own methods of working whilst ensuring Construction and Maintenance of the Al that commitments made by the Executive to third parties were respected as embodied in Expressway in 2001. Five tenderers were the contract documents. Tenderers were able to asked to present their proposals to take submit their own proposals for the time taken to forward the scheme developed by Carl Bro complete the works, subject to a maximum time and develop specific proposals for Design and set by the Executive. Construction in line with the Road Orders, Environmental Statement, the Employer's The contract was awarded in March 2002 to Requirements and the land made available for Balfour Beatty Civil Engineering with Scott the Works.