Design of AirfieldPavement Airfield vs. Highway Pavements • Repetition of load • Distribution of traffic • Geometry of the pavement Affected by pavement width and type of aircraft Plan View of Basic Types of Wheel Configuration a) single trailer-truck unit b) tricycle landing gear with single tires c) twin-tandem landing gear d) double twin-tandem gear . . . . . Rigid Airport Pavement Design • PCA method • Corps of Engineering method • FAA method: based on the Westergaard analysis of edge loaded slabs . FAA Pavement Design Principles • Design Advisor Circular – AC 150/5320-6D Airport Pavement Design and Evaluation Provides guidance from the Federal Aviation Administration for airfield pavement design . 5% nose gear) • Landing gear type and geometry • Single gear aircraft • Dual gear aircraft • Dual tandem gear aircraft • Wide body aircraft – B-747. B-767. L-1011 • Tire pressure: 75 to 200 psi (515 to 1.Aircraft Considerations • Load (95% main landing gear.380 kPa) • Traffic volume . DC-10. . Design Procedure • Forecast annual departures • Select design aircraft that requires the thickest pavement • Transform other aircrafts to equivalent departures of design aircraft . Determination of Design Aircraft • The required pavement thickness for each aircraft type should be checked using the appropriate design curve and the forecast number of annual departures for that aircraft • The design aircraft is the aircraft type that produces the greatest pavement thickness • The design aircraft is not necessarily be the heaviest aircraft in the forecast . . . Principles of Rigid Airport Pavement Design • Based on Westergaard analysis of edge loaded slabs • • • • (modified to simulate a jointed edge condition) Determine k value for rigid pavement Concrete flexural strength Gross weight of design aircraft Annual departures of design aircraft . Item P-209: crushed aggregate base course • .000 lbs) • .Item P-401: plant mix bituminous pavements .Item P-401: plant mix bituminous pavements • Stabilized subbase (aircraft weight > 100.Item P-304: cement treated base course • .Item P-304: cement treated base course • . subbase • Types of subbase courses • .Item P-208: aggregate base course • .Item P-211: lime rock base course • .Subbase Requirements • A minimum thickness of 4 in.Item P-154: subbase course • .Item P-306: econocrete subbase course • .Item P-306: econocrete subbase course • . . . . . the reduction applies only to the concrete slab thickness • The change in thickness for the transitions should be accomplished over an entire slab length and width .9T • For variable section of the transition section and thinned edge.Critical and Noncritical Areas • Total critical pavement thickness = T Noncritical pavement thickness (for concrete slab thickness) = 0. .Design Steps • Several thickness of subbase thickness should be tried => most economical section • Assume P-304 (cement treated base course) to be used • Trial thickness of subbase = 6 in.