The US sister company of Oxford-based geotechnical specialists Maccaferri, has won the contract to supply geo-grid soil reinforcement products for use in the reconstruction of the collapsed, I-35W St Anthony Road Bridge in Minnesota USA.
The bridge, which failed in spectacular fashion in August 2007, is being rebuilt as a 10-lane crossing of the Mississippi River in downtown Minneapolis, Minnesota.
Maccaferri Inc of Williamsport, Maryland, is supplying 9000sq m of its Terramesh, Steel Geo-grid Soil reinforcement units for use in reinforced earth approach ramps to the main bridge and subsidiary slip roads. Seven walls up to 8.5m high will be built incorporating the company’s Terramesh units.
The contract is one of the largest ever undertaken by Maccaferri Inc and is worth over $450,000 to the company. Delivery of the Terramesh components begins in March 2008 and construction is expected to continue for several months. The new bridge is scheduled for completion in December 2008.
The Maccaferri Terramesh system comprises pre-assembled, heavy duty wire cages, similar in concept to gabions, which work with geogrids to create a reinforced earth structure of immense strength and structural stability.
For the bridge ramps, the Terramesh cages act as a containment medium into which locally sourced stone is placed. Double twist steel wire mesh reinforcement grids are laid horizontally behind the wall face and are sandwiched between layers of compacted, site-won back-fill.
For this application, the Terramesh units are manufactured with a PVC coated welded mesh panel front face to meet the projects’ architectural requirements. A special, factory-made connection joins the welded fascia panels and the double-twist steel wire mesh reinforcement grids and eliminates this connection detail on site, saving installation time. Layers of locally sourced stone are then placed within the Terramesh units to achieve the desired aesthetic appearance of geological strata.
According to Maccaferri’s Technical Manager, David Crowther, “The Terramesh system is a technical/structural alternative to reinforced concrete or crib walls. It is a straightforward and very quick system to install and will provide optimum durability up to 120 years, in accordance with the strictest international criteria. This project required HITEC approval to be granted on the system, similar to the BBA Certificates granted in the UK.”
Maccaferri’s Terramesh in various forms, is widely used in the UK and Europe and is part of a comprehensive range of slope reinforcement and soil bio-engineering products from the Company.