Working To Make Air Convection Embankments (ACE) More In This Issue .

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DOT Statewide Research, Development,& Technology TransferLocal Technical Assistance ProgramKeeping Alaska moving through service and infrastructure with applied research, training, and technology transferSpring 2020, No. 93In this issue . . . Air Convection Embankments Transportation AssetManagement Update AASHTO Releases NewEdition of Pavement DesignGuide New Faces at Research Telecommuting Resources onMicrosoft Teams Online TrainingWorking to Make Air ConvectionEmbankments (ACE) MoreEfficient and Cost EffectiveCompiled from the research proposals of Douglas J. Goering, PhD, PE; andSteve McGroarty, PEAir Convection Embankments(ACE) have been part of a numberof highway construction experimental features in the Interior overthe past 20 years. The effectivenessof ACE has been well documentedand they are recognized as an effective mitigation to prevent thawsettlement in permafrost-rich soils.The research project “ImprovedPermafrost Protection using AirConvection and Ventilated Shoulder Cooling Systems” will use datafrom past and current ACE featuresMatt Billings, Alaska DOT&PF Geotechnical Engineer, installs datalogger hardware in weather proof case as part of the Alaska HighwayACE experimental develop a thermal model to helpthe DOT&PF design more efficientACE structures.What are we hoping to learn?The Thompson Drive dataanalysis will be augmented withdata available from other projects,including the Alaska HighwayMP 1354 –1364 ExperimentalFeature, the Dalton Highway MP209–222 Experimental Feature,and the Elliot Highway MP 0–12Experimental Feature, as that additional data becomes available.The results will be summarized invisual and tabular formats so thatthe details of the thermal patternsgenerated within the roadwayembankment and foundation soilscan be easily understood and potentially applied to new construction projects that are consideringapplication of this technology.The analysis of that field datacould then be used to help provideverification data for model development. It is anticipated that a verifiedmodeling approach will become animportant design tool and will helpwith the generation of a modeling(continued on page 2)

(continued from page 1)and design guide. This would give department geotechnical engineers the knowledge they need to ensurean adequate level of cooling effectiveness, while at thesame time optimizing material requirements to reduceconstruction costs.If money was no object, we’d see ACE embankments or ACE shoulders in numerous locations, maybefor long stretches of Interior highways. Unfortunately,the cost of hauling the amount of angular rock believed to be necessary is cost prohibitive.Can we make ACE more cost effective byusing different rock?On the Alaska Highway MP 1354–1364Experimental Feature, the research is investigatingif round rock can be used rather than angular rock.Round alluvial rock is more readily available in theInterior so it would have the potential for shorter haulsACE experimental feature on the Alaska Highway atMP 1354–1364. On the left two data loggers gathertemperature data year round, which is transmitted to avendor via satellite.and would not need to be crushed —both significantcost savings.This experimental feature proposed to examine thefollowing: Could ACE be constructed out of round rock (alluvial cobbles)? Are there differences in the thermal performanceof ACE constructed out of round rock vs. angularACE fill material? Is the long-term pavement performance differentbetween ACE constructed with round rock vs. constructed with angular ACE fill material?Can ACE be more cost effective by using lessrock? How low can we go?On the Dalton Highway we are testing the effectiveness of an insulated conventional embankment withvariable ACE ventilated shoulder top-widths. On thissection of the Dalton, located at MP 219 over thawunstable ice-rich permafrost foundation soils, we willexamine the question of “What is the minimum effective top-width of an ACE Shoulder?” This is functionally equivalent to examining the thickness of the ACEshoulder layer. Existing ACE shoulders in Alaska havebeen constructed with 10- to 15-foot wide shoulders.If this can be reduced to 5 feet, this would represent a50% to 67% reduction in ACE fill requirements withcorresponding cost savings.This experimental feature proposes to examine thefollowing: Performance of ACE shoulders with reduced topwidths. Performance of ACE shoulders on road embankments with different heights above the surroundingoriginal ground surface. Performance of 3"–5" angular vs. 5"–8" angularACE shoulders of equal top-widths. Minimum thickness of ACE shoulders for 3"–5"and 5"–8" angular ACE Fill.With over a decade of data from Thompson Drive,and new data from the Dalton and Alaska Highwayexperimental features, there’s reason to believe thatimproved ACE design will lead to more efficient andcost-effective installations. In about a year, at the conclusion of this project, results will be made availableon the Research & T2 website and in this newsletter.How does an ACE work? Air convection embankments (ACE) and ventilated shoulders have been used inseveral DOT construction projects over the past 15 years to combat permafrost thawing, and their use isexpanding as their performance in the field is better understood. These systems are designed to counteractwarming from construction disturbance and increasing climatic temperatures by providing a cooling influence to keep permafrost foundation soils from thawing and deforming the embankment geometries.A properly designed ACE embankment fill promotes circulation of pore air within the embankment withheat being picked up at the bottom of ACE layer (top of foundation) and released at the embankment surface.The permeability of ACE fill material must be very high to allow the kind of air movement that makes thematerial a good convective heat transfer system.During the winter, low temperatures cool the ACE embankment at its upper surface. If the wintertimecooling effect is strong enough and the ACE material is permeable enough, natural convection cells begin tooperate within the embankment mass. The figure below illustrates convective air movement within an ACEembankment. Convection occurs because the wintertime air temperature/density gradient is such that cold,dense surface air descends as warmer, less dense air moves upward. With the advent of summer warming,the top of the ACE embankment warms to the point where the pore air temperature/density gradient reversesand becomes stable. With warm air on the top and cold air at the bottom of the ACE fill, convection ceases.PavementCold air sinksCold air sinksACE material (coarse rock)Warm air risesWarm air risesPermafrostHeat (warmer than outside air)ACE material(course rock)PavementPavementWarm airACE embankmentACE sideslopeCool airHeat (warmer than outside air)Conventionalbase materialPermafrostPermafrostACE material on the sideslopes.2Convectioncells formThe ACE chimney effectalso acts as a one-wayheat transfer device.When ACE materialis placed on thesideslope, the movementof cold air passingthrough cools theembankment adjacentto the sideslope andtransfers the heat to theair. The air is warmedslightly by the warmembankment and thenescapes up through therock.ACE material under pavement and on the sideslopes3

Transportation Asset Management UpdateThe FAST Act and MAP21 require the use ofperformance-based planning and asset managementsystems. To meet these requirements, the departmenthas developed a policy and procedure for the selectionof highway and bridge maintenance, preservation,rehabilitation and reconstruction projects and has initiated two research projects.The first research project’s goal is to recommend new criteria for the selection of StatewideTransportation Improvement Program (STIP) projectsusing data and performance-based planning. Thesecond is a life-cycle planning project to determine thelevel of funding required to maintain the highway andbridge systems in a state of good repair. These effortswill lead to transparency in how decisions are madeand maximize the use of available funds.The new Pavement Management and BridgeManagement Systems will be used to produce lists ofrecommended projects. The regions will then evaluatethese lists to develop and initiate preservation and minor rehabilitation projects. Identified needs for majorrehabilitation and reconstruction will be reviewedfor inclusion in the STIP. Regional and statewidemanagement teams met this February to assess therecommended projects and will create finalized projectrecommendations by September to begin initiatingnew projects.The Performance-Based Planning andProgramming research project will recommend criteria for strategic decision-making in the prioritizationof STIP projects. As much data as possible will beused during this process, allowing for increased transparency and justification when projects are selected.This will provide the department with the ability toefficiently maintain pavement and bridge assets in astate of good repair, modernize our existing facilities,and expand capacity where required.The Life Cycle Planning Project will be usedto determine the funding required to maintain theNational Highway System in a state of good repair.The Pavement Management and Bridge ManagementSystems will be used to predict conditions over a 20year period given different funding scenarios. Thiswill enable the department to select adequate fundingto meet our federal targets and maintain the pavementand bridges at the desired level of service. Below is anexample of a draft 10-year investment scenario fromthe Pavement Management System showing predictedfederal conditions of good, fair, and poor pavementsacross the NHS.These efforts are ongoing, and between them thedepartment will be able to make transparent, datadriven decisions that meet the requirements of bothMAP21 and the FAST Act for performance-basedplanning and asset management.Percent10 Year Projected Federal Conditions - 110 million 24Fair202520262027Poor20282028AASHTO Releases New Edition ofPavement Design GuideAASHTO Publications has released the third editionof its pavement design guide Mechanistic-EmpiricalPavement Design Guide: A Manual of Practice.Developed by the AASHTO Committee onMaterials and Pavements, this guide describes thepavement design methodology termed mechanisticempirical (M-E) pavement design. Based on engineering mechanics that have been validated throughextensive road test performance data, the guidepresents information necessary for pavement designengineers to use the M-E design and analysis method.Updates Since 2015 Second EditionThis new 2020 third edition, which supersedes the2015 second edition, includes a number of revisionsand updates, including the following: new fracture mechanics-based model for reflectivecracking in AC overlays over flexible, semi-rigid,and rigid pavements; new mechanistic-empirical model for short jointedplain concrete pavement overlays of flexible pavements; new flexible and semi-rigid pavement global calibration coefficients; the addition of non-structural preventative maintenance treatment consideration for flexible andrigid pavements; the addition of five level 3 default distributions fornormalized axle load spectra; updated climate discussion for Modern Era Retrospective Reanalysis and North American Regionalreanalysis data; the incorporation of crack load transfer efficiencyfor flexible pavements; expanded guidance for creep compliance and indirect tensile strength inputs for asphalt wearingsurface layers; and updated standards references.Available FormatsThe guide is available in three formats: In a printedpaperback; as a PDF download single-user, 5-user, or10-user; and in a set that includes both the paperbackversion and the single-user PDF download version, at adiscounted rate.Order a Copy!To order a copy of the new Mechanistic-EmpiricalPavement Design Guide: A Manual of Practice, 3rdEdition, visit the AASHTO Store online at search by the publication’s item code, MEPDG-3,or click on this link directly to the publication's pageon the AASHTO tionDetail?ID 196&AspxAutoDetectCookieSupport 1Related Software:AASHTOWare Software:The Mechanistic-Empirical Pavement DesignGuide: A Manual of Practice, 3rd Edition referencesthe AASHTOWare Pavement ME Design M-EPavement design software, commercially availablethrough AASHTOWare, AASHTO's software development program. ent-overview/Related PublicationsWhen you order your copy of the new MechanisticEmpirical Pavement Design Guide: A Manual ofPractice, 3rd Edition, be sure to also order copiesof these two related AASHTO publications, whichprovide additional information and guidance onmechanistic-empirical pavement design, and pavementengineering:Guide for the Local Calibration of the MechanisticEmpirical Pavement Design Guide, 1st Edition;andPavement Design, Construction, and Management: ADigital Handbook, 1st Edition.This is a draft scenario run for the Life Cycle Planning projectand does not reflect the selected investment level in the TAMP.45

Two New Faces at ResearchErin Anderson recentlyjoined the Development,and Technology Transferdivision. Erin graduatedfrom the University ofAlaska Fairbanks with adegree in geological engineering in 2001. She spentthe past six years workingin the Northern RegionConstruction section.Before that, Erin spenttime working in Utilitiesand Highway Design. Erin lives in Fairbanks with herfamily and enjoys shoveling snow.Ian Grant is theresearch engineer based inJuneau at the AKDOT&PF3-Mile Headquarters. Iangraduated in 2018 fromthe University of AlaskaFairbanks with a degree inmechanical engineering.Ian is currently workingon eight projects for Research, Development, andTechnology Transfer division. These projects include topics dealing with environmental preservation,bridge infrastructure, and hydraulic modelling. Ian isexcited to help AKDOT&PF in its progress towardsfuture development.National Highway Institute Online TrainingThis could be a good time for online training offeredby the National Highway Institute (NHI).Many of the courses NHI offers online can beused toward obtaining Continuing Education Units(CEUs), Certification Maintenance (CM) credits, andProfessional Development Hours (PDHs) fortransportation professionals.Start now by creating an account with your AlaskaDOT&PF email account. We always encourage everyone to talk with your supervisor before enrolling inT2 or non-T2 sponsored ?tab 0&sf 1Telecommuting Resources on Microsoft TeamsFor those of you who are teleworking, we know thetransition to a new workspace without all of yourusual comforts can be hard. Our IT team is ready tohelp you transition into your new space and help youtroubleshoot all your tech problems. They have puttogether a statewide resource on Microsoft Teams tohelp you through some of the most common problemslike forwarding your phone, using a VPN, and settingup WebEx. Please check out the Telecommuting Resources Public Team by clicking this link.6Take some time to explore what’s available andyou may learn something new. (Did you know youcan turn your voicemails into emails?) If you can’tfind what you’re looking for, use the chat page on theQuestion and Answer Channel to get answers to yourquestions. The team will be updated regularly withnew resources, tips, and tricks to get you through yourteleworking experience.7

Online Training Available on the T2 Website Commercially Useful Function (CUF) Federal-aidHighway Program Video Training Wetlands Stormwater Hazard Communication Airports MSGP Training Introduction to Title VI Training Inspection Report Form 25D-100 Instructions{ Natural Occurring Asbestos: Asbestos AwarenessTraining Natural Occurring Asbestos: Competent PersonTraining Natural Occurring Asbestos: Project DesignerTraining RBA: Operate Alaska’s Marine TransportationServices RBA: Modernize Alaska’s TransportationInfrastructure RBA: Operate Alaska’s TransportationInfrastructure NEPA Procedures Manual Training, Module 8:Section 4(f) and 6(f) NEPA Procedures Manual Training, Module 9:Endangered Species Act and Marine MammalProtection Act NEPA Procedures Manual Training, Module 10:Cultural ResourcesHow to enroll:1. Go to our link: . Log in to your account or create an account(sidebar, bottom right)3. Find “on-line training” under the Training Linkson the sidebar.4. “Add on-line training” to your ScheduledTraining and you’re ready to go.8June 2020Alaska Flexible Pavement DesignJune 25–26 in FairbanksSeptember 2020131139: Constructing and InspectingAsphalt Paving ProjectsSep 1 to Sep 2 in FairbanksOctober 2020A Guide to PEL and AcceleratedProject DevelopmentOct 27 to Oct 27 in AnchorageFHWA-NHI-134077:Contract Administration Core CurriculumOct 26 to Oct 27 in AnchorageOct 29 to Oct 30 in JuneauThe current training calendar can be found at:November 2020FHWA-NHI-380032A:Roadside Safety DesignNov 3 to Nov 5 in AnchorageT NEPA Procedures Manual Training, Module 1:Environmental Procedures Overview NEPA Procedures Manual Training, Module 2:Class of Action Determination NEPA Procedures Manual Training, Module 3:Categorical Exclusions NEPA Procedures Manual Training, Module 4:Environmental Assessment and Finding of NoSignificant Impact NEPA Procedures Manual Training, Module 5:Environmental Impact Statement NEPA Procedures Manual Training, Module 6:Re-Evaluation NEPA Procedures Manual Training, Module 7:Public and Agency InvolvementUpcoming alendarFor periodic emails about research, sign up for info/dot-researchnotificationFor periodic emails about training, sign up for info/dot-trainingnotificationFor information about T2-sponsoredtraining, contact:Dave Waldo at 907-451-5323,david.waldo@alaska.govSimon Howell at 907-451-5482,simon.howell@alaska.govFor any other information about T2-sponsored training, contact:Dave Waldo at 907-451-5323,david.waldo@alaska.govorSimon Howell at 907-451-5482,simon.howell@alaska.govor go to:

AASHTO T3 TrainingAvailable Freefor Alaska DOT&PFEmployeesJust create an account with your Alaska DOT&PFemail account. Remember, we encourage everyoneto talk with your supervisor before enrolling in T2 ornon-T2 sponsored sources/courses/Anna Bosin, P.E., Research Program Manager907-269-6208, anna.bosin@alaska.govDrew Pavey, Pavement Management Engineer907-269-6213, andrew.pavey@alaska.govDave Waldo, T2 Manager, Editor907-451-5323, david.waldo@alaska.govSimon Howell, Training Specialist907-451-5482, simon.howell@alaska.govErin Anderson, Research Engineer907-451-3055, erin.anderson@alaska.govIan Grant, Research Engineer907-465-3447, ddes/research/sramNationP & TTAPTAPrlLogaHundreds of courses in severaltopic areas: Construction Maintenance Materials Traffic and Safety Pavement Preservation Employee DevelopmentResearch, Development, andTechnology Transfer StaffemgeAgAgenciesServinrica’sridLocal Road & BThis newsletter is funded by the Federal HighwayAdministration and the Alaska Department ofTransportation and Public Facilities. The materialcontained herein does not necessarily reflect the viewsof the Alaska Department of Transportation, FederalHighway Administration, or the T 2 staff. Any reference toa commercial product or organization in this newsletteris only for informational purposes and is not intendedas an endorsement.Local Technical Assistance ProgramDepartment of Transportation and Public Facilities2301 Peger Road M/S 2550Fairbanks, AK 99709-5399

the top of the ACE embankment warms to the point where the pore air temperature/density gradient reverses and becomes stable. With warm air on the top and cold air at the bottom of the ACE fill, convection ceases. Pavement ACE sideslope ACE embankment Conventional base material Permafrost Pavement ACE material (course rock) Cool air Warm air

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