Bridges
Flatiron engineered a new way to build bridges that minimizes environmental impact. The company designed a gantry that drives piles, lays prefab road segments and places girders. Once one segment is done, the gantry shifts forward to work on the next. This eliminates the need for large cranes and temporary access trestles in the fragile wetlands throughout the site. The novel system effectively turns the work of building an entire bridge into a production line. Flatiron first used the new method on the Highway 17 Bypass near Washington, which traverses a nature reserve. We secured the contract in competitive bidding with selection criteria that included environmental compat ibility alongside construction cost. For helping to develop the innovative bridge building technique, Flatiron Vice President Elie Homsi was honored by US trade magazine Engineering NewsRecord with a Top 25 Newsmaker award for 2008.
A joint venture including HOCHTIEF Construction faced similar challenges in building the Saale-Elster Viaduct. Part of the new Erfurt-Leipzig/Halle rail link, the viaduct has a length of over 8,600 meters, making it the biggest of its kind in Germany. South of Halle, the rail link crosses the Saale and Weisse Elster river floodplains which have a number of nature reserves, among them sites classified under the European Habitats Directive and Birds Directive. Along two stretches of the new line, vehicles are unable to access the site for conservation reasons. The project team therefore erected the 704-meter main span stretching either side of the Weisse Elster using a top-down construction technique. The building work, which will go on until 2012, also halts for several months during the spring breeding season in the bird reserve.
Power generation
In construction of the Glendoe Hydro Scheme situated in peaty moorland in the Scottish Highlands, a large protected area, HOCHTIEF Construction complied with stringent environmental stipulations. The region is home to numerous protected animal species including the golden eagle and the otter as well as rare species of plant. Throughout the project, two on-site environmental engineers made sure all those involved acted responsibly and trained construction staff in environmental matters. A notable example of species conservation resulted from much of the work being in areas with active colonies of water vole, a species whose habitats are protected by law in Scotland. The environmental specialists located vole colonies, mapped them and marked their locations around the site so access tracks and construction works could be made to skirt around them. Turf and glacial till removed when creating tracks was later reused in site rehabilitation. The project team also devoted a great deal of care to conserving the rare Bryum muehlenbeckii moss species. The few locations in Scotland where this species is found include rocks beside the Tarff, a river dammed in construction of the reservoir. A bryologist was responsible for its transplantation. Rock extracted in tunneling was carried off site by a conveyor system, enabling the project team to avoid the use of vehicles.*
The Swanbank Waste Management Facility is a green project by Leighton subsidiary Thiess in which waste is turned to energy in a process called ReOrganic Energy. The facility has the potential to cut carbon emissions by 364,000 metric tons a year. It can generate enough energy to supply 9,400 homes. The project is the first privately operated landfill in Australia. It is the second of its kind in the world to use landfill gas for electricity generation. The facility also uses leachate recirculation technology to accelerate the production of landfill gas. The landfill gas is then harnessed and pumped