Airport Pavement

Airport PavementDesign andEvaluationAC 150/5320-6FOverview of ChangesPrepared by Doug Johnson, P.E.Sr. Civil Engineer - PavementFAA Airport Safety & StandardsAirport Engineering AAS-100Presented by Cindy Hirsch, P.E.Lead Civil EngineerFAA Airport Safety & StandardsNorthwest Mountain Regional OfficeFederal AviationAdministration

Overview AC 150/5320-6F Airport Pavement Design andEvaluation– What’s Different– FAARFIELD v1.305 vs v1.41 All Pavement Design in Chapter 3 Defined ‘regular’ use Tables for Minimum Layer Thickness Detail Transition Hot Mix Asphalt (HMA) to PCC Revised Text and Examples to FAARFIELD v1.41 Added Appendix on Nondestructive TestingFederal AviationAdministration

AC 150/5320-6F OrganizationChapterTopic1Airport Pavements – Their Function and Purpose2Soil Investigations and Evaluation3Airport Pavement Design4Pavement Rehabilitation5Pavement Structural Evaluation6Pavement Design for ShouldersAppendix ASoil CharacteristicsAppendix BDesign of StructuresAppendix CNondestructive Testing (NDT) using falling-weight type impulse loaddevicesAppendix DReinforced Isolation JointAppendix ERelated Reading MaterialFederal AviationAdministration3

AC 150/5320-6F Why Change Updated FAARFIELD v1.41– AC is what issues update Just Airport Pavement Design– no longer a separate chapter on light duty designsince all designs require use of FAARFIELD Tables of minimums based upon weight More emphasis on evaluation step by step examplesFederal AviationAdministration

FAA Pavement Design Flexible Pavement– Layer elastic theory Rigid Pavement– Three-dimensional finite element theory Requires FAA computer programFAARFIELD– FAA Rigid and Flexible Interactive Elastic DesignFederal AviationAdministration

Selection of Pavement TypeFederal AviationAdministration

Selection of Pavement TypeRemember what you need the pavementto do: Provide a surface to safely operateaircraft Provide one that is smooth, durable,FOD-free surface, properly drainedand with adequate macro / microtexture to facilitate control of aircraftFederal AviationAdministration

Selection of Pavement Type It is assumed that all alternativeswill achieve desired result Cost Effectiveness Analysisfollowing OMB A-94Federal AviationAdministration

Typical Pavement StructureFederal AviationAdministration

Typical Pavement Structure Surface: Surface courses typically include Portlandcement concrete (PCC) and Hot-Mix Asphalt (HMA). Base: Base courses generally fall into two classes:unstabilized and stabilized.– Unstabilized bases: crushed and uncrushedaggregates.– Stabilized bases: crushed and uncrushedaggregates stabilized with cement or asphalt. Subbase: Subbase courses consist of granularmaterial, which may be unstabilized or stabilized. Subgrade: Subgrade consists of natural or modifiedsoils.Federal AviationAdministration

Minimum Layer ThicknessFlexible Pavement StructuresFederal AviationAdministration

AC 150/5320-6F Lots of information in the footnotes When substituting material consider what youneed the material to doFederal AviationAdministration

Structural Layer Thickness vsConstruction Layer Thickness Minimum Construction Lift Thickness 4-6 x nMAS Gradation 13 inches Gradation 22 inches Gradation 31-1/2 inches Research supports thicker liftsperform betterFederal AviationAdministration

Subgrade SupportCBR 5 Recommend ImprovementCBR 3 Require ImprovementFederal AviationAdministration

Subgrade Drainage See AC 150/5320-5, Appendix G fordesign guidance on subsurface drainage Soil k 20 ft/day: subsurface drainagelayer recommendedFederal AviationAdministration

Chapter 3 Pavement Design Design Guidance for Airfield Pavements– All pavement designs require FAARFIELDno differentiation between light and aircraft 30K– Tables of Minimum Layer Thickness by weight Stabilized Base Course– Full Scale Performance Tests prove that pavementswith stabilized bases have superior performance– Exception: 5% Traffic 100K and 110KFederal AviationAdministration

Pavement Life Structural Life: Strength to carry loads Functional Life: Acceptable Service relative to:foreign object debris (FOD), Skid Resistance orroughness FAARFIELD Structural Life Design Life Theoretically possible to perform for any period Actual Life f(airplane mix, quality of materialsand construction, routine & preventativemaintenance)Federal AviationAdministration

Pavement LifeTypically, pavements on federally funded FAA projects are designed for a 20 yearstructural life. Designs for longer periods may be appropriate at airfields where theconfiguration of the airfield is not expected to change and where future traffic can beforecast with relative confidence beyond 20 years. A longer design life may beappropriate for a runway at a large hub airport where the future aircraft traffic can beforecast and where both the location and size of the runway and taxiways is notanticipated to change. However, when designing a taxiway at a smaller airport it may bemore prudent to design for no more than 20 years, than to try to forecast thecomposition and frequency of future activity. Many airports have significant changesplanned, but whether these plans ultimately become reality depends on local economicconditions, (e.g. business upturns or downturns at the fixed base operator (FBO), and thenumber and composition of based aircraft). Typically a life cycle cost effectivenessanalysis is utilized to support design periods other than 20 years. However, fiscalconstraints (i.e. funds available) may dictate which pavement section(s) and design lifeis considered.Longer life not appropriate for all airportsFederal AviationAdministration

No Maintenance Reduced LifeNo pavement will achieve itsdesign life without routine andpreventative maintenance.Federal AviationAdministration

Traffic In general design for‘regularly’ using aircraft ‘Regular’ use 250 annual departures(500 operations) Sensitivity analysis for occasional orseasonal– Design Section– After adjusting structure for rounding and constructionevaluate impact of all aircraftFederal AviationAdministration

FAARFIELD 1.4 – What’s New?FAARFIELD 1.4 has: Completely revised flexible and rigid failure modelsbased on newest full-scale test data. Improved, more accurate 3D finite element model. Completely rewritten concrete overlay design procedure. Support for user-defined gear configurations. Updated aircraft library aligned with COMFAA 3.0. Automated, software-based compaction criteria. All data files now stored in document directories. Automatically generates PDF design report.Federal AviationAdministration

Automated Compaction CriteriaComputes compaction control points for rigid & flexible pavements.Federal AviationAdministration

Compaction TablesPercent of Max.Dry DensityDepth fromSurfaceDepth from Topof SubgradeCritical Airplanefor CompactionSubgrade Compaction RequirementsNonCohesive SoilPercent Maximum Dry Density(%)1009590Depth of compactionfrom pavement surface (in)0 - 3434 - 105105 - 177Depth of compactionfrom top of subgrade (in)0-55 - 7676 - 148Depth of compactionfrom pavement surface (in)0 - 3030 - 7878 - 127127 - 174Depth of compactionfrom top of subgrade (in)0-11 - 5050 - 9898 - 145Critical Airplane for CompactionA380 BellyA380 BellyA380 BellyCohesive SoilPercent Maximum Dry Density(%)95908580Critical Airplane for CompactionA380 BellyA380 BellyA380 BellyA380 BellySubgrade Compaction Notes:1. Noncohesive soils, for the purpose of determining compaction control, are those with a plasticity index (PI) less than 3.2. Tabulated values indicate depth ranges within which densities should equal or exceed the indicated percentage of the maximumdry density as specified in item P-152.3. Maximum dry density is determined using ASTM Method D 1557.4. The subgrade in cut areas should have natural densities shown or should (a) be compacted from the surface to achieve therequired densities, (b) be removed and replaced at the densities shown, or (c) when economics and grades permit, be covered withsufficient select or subbase material so that the uncompacted subgrade is at a depth where the in-place densities are satisfactory.5. For swelling soils refer to AC 150/5320-6E paragraph 313.Modified Proctor (Heavy Load)Federal AviationAdministration

Aircraft Libraries FAARFIELD & COMFAAaircraft libraries aligned tothe extent possible. All Multigear AC split intomain & belly, but linked forweight & activity Included new aircraft:––––A350-900 (Preliminary)B747-8B787-9Embraer FleetFederal AviationAdministration

Typical Details (new)Note: Not shown, but good idea to seal jointbetween HMA and PCCFederal AviationAdministration

Overlay Design Reason for Rehabilitation– Why is pavement ready for rehabilitation– Structural, material distress, other Start with condition assessment– Complete assessment of pavement materials andstructural integrity– Thickness, condition, nature and strength of eachlayer Design must correct reason forrehabilitationFederal AviationAdministration

Overlay FAARFIELD overlay design– Layered Elastic and finite element analysis Four types of overlay– HMA overlay of flexible or rigid– PCC overlay of existing flexible or rigid Structural Overlay– Minimum 3”– Thicker overlays better long term performance Non-Structural Overlay– Minimum 2”Federal AviationAdministration

Preparation for Overlay Defective areas in base, subbase andsubgrade must be correctedFederal AviationAdministration

Reporting Weight Bearing Strength Aircraft Classification Number /Pavement Classification Number(ACN/PCN) ICAO Standardized Method USA Procedure in AC 150/5335-5C FAA Software Program COMFAA & ExcelSpreadsheet to facilitate evaluation Report on FAA MasterRecord 5010Federal AviationAdministration

Chapter 6:Pavement Design for Shoulders Paved shoulders– Required for Aircraft Group IV and higher– Recommended Aircraft Group III Stabilized Shoulders– Recommended Aircraft Group I & II– (Turf, aggregate-turf, soil cement, lime or bituminousstabilized soil) Most Demanding of– 15 Passes of most demanding airplane oranticipated traffic from maintenance vehiclesFederal AviationAdministration

Chapter 6:Pavement Design for ShouldersFederal AviationAdministration

Appendix E: Variable Section RW450'[137 M] No change still allowed(just rarely done)– Keel 100% traffic– Outer edge 1% traffic– transitions between30 450'[137 M]250'[76 M]A250'[76 M]250'[76 M]PIASEE NOTE 4SEE NOTE 5RUNWAY WIDTHSLOPEBASESUBBASESUBGRADE25'[7.6 M]MINIMUM25'[7.6 M]MINIMUM25'[7.6 M]MINIMUM25'[7.6 M]MINIMUM25'[7.6 M]MINIMUM25'[7.6 M]MINIMUMA-ASECTION(FOR HMA)NOT TO SCALESEE NOTE 4RUNWAY WIDTHSEE NOTE 5SLOPEBASESUBBASESUBGRADE18.75' [5.7 M]MINIMUM18.75' [5.7 M]MINIMUM18.75' [5.7 M]MINIMUM37.5' [11.4 M]MINIMUM18.75' [5.7 M]MINIMUM37.5' [11.4 M]MINIMUMA-ASECTION(FOR PCC)NOT TO SCALELEGEND:NOTES:1. RUNWAY AND TAXIWAY WIDTHS, TRANSVERSE SLOPES, ETC.PER AC 150/ 5300-13, AIRPORT DESIGNFULL PAVEMENT THICKNESS(DESIGN USING 100% DEPARTURE TRAFFIC)2. SURFACE, BASE, PCC, ETC. THICKNESS PER AC 150/5320-6.PAVEMENT THICKNESS TAPERS TO REDUCEDTHICKNESS OF OUTER EDGE THICKNESS, FULLPAVEMENT THICKNESS AND/OR HIGH-SPEEDTAXIWAY EXITS AND SIMILAR.3. SECTIONS BASED ON 150 FT [46 M] RUNWAY WIDTH.4. MINIMUM 12 INCHES [30 CM] UP TO 36 INCHES [90 CM] ALLOWABLE.5. CONSTRUCT A 1.5 INCH [4 CM] DROP BETWEEN PAVED ANDUNPAVED SURFACES.6. WIDTH OF TAPERS AND TRANSITIONS ON RIGID PAVEMENTS TOBE AN EVEN MULTIPLE OF SLABS, MINIMUM ONE SLAB WIDTH.OUTER EDGE THICKNESS(DESIGN USING 1% DEPARTURE TRAFFIC)HIGH-SPEED TAXIWAY EXITS AND SIMILAR(DESIGN USING ARRIVAL TRAFFIC)TYPICAL PLAN AND CROSS-SECTION FOR RUNWAY PAVEMENTFederal AviationAdministration

Doug Johnson, P.E.Doug.johnson@faa.gov(202) 267-4689Greg Cline, P.E.Gregory.cline@faa.gov(202) 267-8814Questions?Federal AviationAdministration

Federal Aviation Administration Overview AC 150/5320-6F Airport Pavement Design and Evaluation –What’s Different –FAARFIELD v1.305 vs v1.41 All Pavement Design in Chapter 3 Defined ‘regular’ use Tables for Minimum Layer Thickness Detail Transition Hot Mix Asphalt (HMA) to PCC Revised Text and Examples to F