A joint English and French project involved boring three tunnels through 31 miles of a chalk marl formation to link the cities of Dover and Calais. Two tunnels will accommodate high-speed trains; the third will be a service tunnel. The tunnels are lined with precast concrete ring segments. The bases for the tunnel rail bed and two sidewalks (one for evacuation and one for maintenance) are paved with concrete.
Montcocal, the contractor for the French share of the paving work, asked Power Curbers Inc., a Salisbury, N.C., slipforming paving machine manufacturer, to design equipment that could speed concrete placement and meet the job's unusual requirements. The company furnished three pieces of custom slipforming equipment: one machine to pave the rail bed, and two to pave the sidewalks.
Montcocal estimates that it doubled its paving production using the slipforming equipment instead of pouring concrete into forms and hand-finishing. The 3 machines paved 30 miles of rail bed and 60 miles of sidewalk in 8 months.