CONCRETE PIPE Airport Loading An important factor in airport operations is the proper functioning of its drainage facilities. Because of relatively shallow covers associated with subsurface drainage for airfields, and the magnitude of wheel load concentrations, the effect of aircraft loads on the structural design of underground pipelines is more critical than for most highway facilities. The pressure distribution of aircraft wheel loads on any horizontal plane in the soil mass is dependent on the magnitude and characteristics of the aircraft loads, including tire pressures, the landing gear configuration, the pavement structure and the subsoil conditions. Larger aircraft have resulted in multiple wheel undercarriages consisting of dual wheel assemblies and dual tandem assemblies to reduce the concentration of load. The net effect is a combination of loadings which impose overlapping pressures, similar to, but heavier than highway loadings. Major airports are paved with relatively strong surfaces of concrete or asphalt materials, which effectively reduce the load intensity on the sub-grade. For asphalt surfaces, either local engineering practice or a nominal increase in pressure intensity over that estimated for concrete can be used. Please contact your local Lafarge representative for additional design assistance when considering projects located near or under an airport runway. Aircrafts present a need for specialized underground infrastructure. Unadvertised in our annual product catalogues are our aircraft rated pipe and manhole material, which are typically thicker and more heavily reinforced. Lafarge has readily available designs for airport manhole material, from concrete pipe to standard or customized manhole material. While many airport project specifications call for concrete beddings or specialized access or maintenance openings, Lafarge is able to review project conditions and provide comment on requirements versus best management practices, utilizing the most up to date project standards across Western Canada. PAGE 34 LAFARGE PIPE eMANUAL