Lehigh Cement Co has been given approval to construct a 4.4 mile long underground conveyor system from the company's quarry to the plant in Union Bridge, Maryland, USA.

The board of the Carroll County Commissioners unanimously approved a zoning amendment enabling the company to proceed with the project. The conveyor will transport about 12,000tpd of stone from the company’s New Windsor quarry to the plant. Lehigh says the conveyor will be 3m to 20m underground.