Rail passengers using Boston's South Station have been able to monitor progress on the Big Dig Project for all of ten years now. Hundreds of trains pass the construction site of this largest infrastructure project in the United States each day. Interbeton, HBG's international group company, is working flat out to complete tunnels, roads and viaducts.
Interbeton is currently working in partnership with three American firms on the 50 subprojects together forming contract C09A4. This includes the construction of two kilometres of road, box-jacked tunnels totalling more than 1,000 metres, a tunnel one kilometre long and 3.5 kilometres of viaduct. HBG's group company is building the viaducts by the cantilever method. This involves placing prefabricated segments by means of a launch gantry. For safety reasons and so as not to impede other construction activities, some of this work is done at night. Particular care is called for where the route crosses a number of railway lines.