When Wai Ling Engineering Co., Kowloon, Hong Kong, was awarded the contract to place concrete for the people-mover tunnels at Hong Kong's new international airport, a tight construction schedule and difficult site access required the use of special material-handling equipment. Because the 110-foot-wide tunnel frame was constructed in an open cut, the side slopes prevented ready mix trucks and boom pumps from getting close enough to the placement area to deliver concrete efficiently. The solution: A special long-span side-discharge conveyor system engineered by Morgen Mfg. Co., Yankton, S.D. CONVEYOR SETUP The truss-supported conveyor spanned 120 feet, extending over the width of the entire tunnel-construction area. Two towers--one on each side of the tunnel excavation--supported the conveyor 33 feet above the work area. Each tower was mounted on a self-propelled undercarriage that traveled alongside the tunnel excavation on double-rail tracks. The assembly also included a 91-foot-long charging conveyor that fed concrete from ready mix trucks on the embankment edge to the side-discharge conveyor, where the concrete was then emptied into tremies of varying length to accommodate tunnel slab, wall, and roof placements. Using the system, Wai Lung achieved placement rates exceeding 170 cubic yards per hour.