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How Vulnerable Is ’s Transportation to Climate Change? Managing an Infrastructure Built on

BILLY CONNOR AND JAMES HARPER

limate change is affecting transportation sys- tems across the country, and scientists and pol- Cicymakers are working to clarify the trends. Alaska’s transportation community, however, has di- rect experience to verify the impacts of climate change. Geography and extreme climate have made the state a kind of climate-change classroom for the rest of the nation in predicting the effects on trans- portation infrastructure. The wear and tear of climate change on Alaska’s transportation systems is evident. The state has more than 6,600 miles of coastline, and approximately 80 percent of the land mass has an underlayer of ice-rich permafrost. Alaska has 17 of the nation’s 20 largest mountain ranges and experiences extremes in pre- cipitation, snowfall, and temperature swings that are unique to the arctic and northern latitudes. With warming permafrost, coastal erosion, and increasingly dramatic storms and flood events, Alaska’s highways, runways, and other infrastruc- ture are frequently icing, cracking, and washing away. Although these adversities challenge all of the state’s major transportation systems—maritime, avi- ation, and surface—the most acute and costly dam- age occurs within the road system. Climate change in Alaska is forcing engineers and planners to adapt both to warming and to cooling trends. Engineers and planners are addressing

knowledge gaps in thermal and hydrological dynam- ENTER C ics and are translating the findings into new and more robust designs. RANSPORTATION T (Right:) Differential settlement on an abandoned NIVERSITY

section of the Richardson Highway, south of U Fairbanks, one year after maintenance ceased. LASKA , A

Connor is Director, and Harper is Communication ONNOR

Specialist, Alaska University Transportation : B. C HOTO

Research Center, University of Alaska, Fairbanks. P 00_TRN_284_TRN_284 3/7/133:00PMPage24 24 TR NEWS 284 JANUARY–FEBRUARY 2013 frequency. mance, temperature,and permafrost byperfor- layer. Engineersclassify just belowthevegetation way, showingtheicelayer along theDaltonHigh- Thawing permafrost mafrost from seasontoseason. has intensifiedtheengineeringchallengesofper- its associatedimpactsonheatingandthawingtrends, thermal andhydrologic forces. Climatechange,with zontal, lenticularicelensesandlarge icewedges. permafrost, whichischaracterizedbysmall,hori- north inthinlayersthatlaterfroze toformsyngenetic rial throughout thevalleyandintohillsto borne silt;glacierstothesouthdepositedmate- permafrost intheTanana Valley was formedbyair- mations. Forexample,agreat portion ofthe sent someofthemostproblematic permafrost for- Tanana Valley—has neverexperiencedaglacier. and thelow-lyingcentralregion knownasthe much ofAlaska—theNorth Slope,westernareas, a dryclimateprevented glacialformation,sothat permafrost wasnotformedbyglaciers;insomeareas, in today’s surface transportation challenges.Most frustration forAlaska’s engineersandplaysakeypart frozen fortwoormore years—hasbeenasource of Permafrost—generally definedassoilcontinuously Permafrost encountered today. and remnant iceburiedinmorainesthatare regularly ago, leavingbehindascarred landscape,permafrost, Glaciers beganretreating approximately 10,000years remains ofachildonthenorthwestern coast( 11,000 yearsago,evidencedbythemummified and permafrost formed.Humansappeared inAlaska The iceagechangedthatlandscape—glaciersgrew dominated Alaska’s more than660,000square miles. Approximately 50,000yearsago,tropical plants Alaska’s ClimateChangeHistory These dynamicsstemfrom theinterplaybetween Even withoutglaciers,however, theseregions pre- 1

).

E N I , K M : P NGINEERING ORTHERN OF NSTITUTE ANEVSKIY IKHAIL HOTO exceeds 3feet. Breakup ontheYukon River;icethicknessusually discharge thatcandescendovertheNorth Slope. when snowpackandsnowmeltcreate apeakflowof spring bringsaphenomenonknownasbreakup, or nearice-andsnow-fedstreams andrivers.Each involves designingandprotecting infrastructure on manage roads andotherinfrastructure. Thetask hydrologic datatoevaluate,design,andeventually National Wildlife Refuge.Plannersneedavarietyof famed DaltonHighway, PrudhoeBay, andtheArctic affecting transportation. Theregion ishometothe ice meltare amongthevariablehydrologic features On Alaska’s North Slope,seasonalstream flowsand Slope North and iceflowpatternsintheserivers andstreams. characterize waterflowvolumes, sedimenttransfer, Alaska are conducting amajorresearch project to and Environmental Research Center, andtheStateof Alaska UniversityTransportation Center, theWater rivers thatflownorth outoftheBrooks Range. The munity ofUmiat—crossing severaliceandsnow-fed the DaltonHighwayacross theslopetoward thecom- terrain. state’s road systemacross theinvariablyinhospitable addressing theseissuesastheyworktoextendthe house. Researchers, engineers,andplanners are then add3-foot-thickicechunksthelengthofa unknown waterandsedimentflowsisadifficult task;

A newtransportation corridorwillrunwestfrom Designing bridgepilingstocross ariverthathas

C T U A , C B. : P ENTER RANSPORTATION NIVERSITY LASKA ONNOR HOTO TR NEWS 284 JANUARY–FEBRUARY 2013 25 Yedoma, a type of Yedoma, syngenetic permafrost, has a frozen moisture content often exceeding 300 percent; photo shows lenticular ice formations of yedoma with ice-rich silt layers between the visible ice. ). The 3 )—the estimate did not )—the estimate did ). Epigenetic permafrost is often found on Alaska’s is often found Epigenetic permafrost Permafrost appears to be the cause of the most appears to be the Permafrost increases infrastructure Alaska’s of The remoteness

Alaska’s engineers encounter two types of per- Alaska’s type of syn- syngenetic and epigenetic. One mafrost: high frozen yedoma, has a genetic permafrost, In percent. content, often exceeding 300 moisture in ice and yedoma is suspended other words, the To turns mostly into water when it thaws. silt. Syn- untrained eye, yedoma looks like frozen of the north typically is found genetic permafrost Alaska Range. Range and south of Slope, above the Brooks North formed sim- was the Alaska Range. This permafrost and moisture in place. The properties ply by freezing content. content vary with the soil type and moisture Types of Permafrost Types severe and costly of these issues. In a newspaper and costly of these severe Chief of Statewide Mainte- Mike Coffey, interview, of Department Operations for the Alaska nance and that and Public Facilities, estimated Transportation million annually on permafrost- the state spends $11 (3 roads issues with related railways, and municipal runways, include airport infrastructure. operations costs. In Anchorage the maintenance and may cost and crushed aggregate or Fairbanks, gravel damaged but in the more per yard, $20 approximately such as Savoonga, the costs can soar areas, and remote fuel, transport, with increased up to $1,000 per yard ( materials placement, and labor expenses costs of permafrost damage to Alaska’s publicly damage to Alaska’s costs of permafrost by an esti- grow expected to are owned infrastructure to $6.1 billion, or $3.6 billion mated 10 to 20 percent, by $5.6 bil- by 2030. By 2080, these costs could grow lion to $7.6 billion (3

E N I , K M : P NGINEERING ORTHERN OF NSTITUTE ANEVSKIY IKHAIL HOTO

PHOTO: MARGARET DARROW, UNIVERSITY OF ALASKA FAIRBANKS Road and infrastructure loss from flooding; and loss from Road and infrastructure slides caused by melt- from Loss of roadways Damage to roadways, airports, and bridges and airports, Damage to roadways, melting movement and damage from Culvert Warming trends exacerbate these dynamics. Heat exacerbate trends Warming u u u u ). The impacts on infrastructure include the fol- ). The impacts on infrastructure 2 lowing: Alaska’s recent climate variations are significantly variations are climate recent Alaska’s of the nation. Alaska those in the rest from different than twice the rate of the con- has warmed at more and tinental United States in the past half-century, has risen by 3.4ºF the annual average temperature ( Costly Impacts Thermal Trends another are at and below the surface Thermal trends in soil temperatures, Studying trends of interest. area clarifies and slope stability ice content, soil strength, slopes in per- mechanisms of unstable soil the failure a typi- conditions are Subsurface regions. mafrost areas, unfrozen and of frozen cally complex mixture The flow and slope stability. groundwater affecting only one active also vary in depth and may have areas deep-seated. layer or may be more sub- in turn increasing permafrost, changes affect Many roads. which affects water flow, surface on the impact of focusing are projects research flow, changes on groundwater temperature Alaska’s instability degradation, and the resulting permafrost and slopes. surfaces in road Researcher Margaret Darrow of the Alaska Researcher Margaret Center checks a thermal University Transportation Dalton modeling data collection station along the hydrological research enables Thermal and Highway. transportation engineers to gain a better of permafrost on road understanding of the effects embankment stability. ing permafrost. from melting permafrost; from or flooding; permafrost 00_TRN_284_TRN_284 3/7/13 3:00 PM Page 25 Page PM 3:00 3/7/13 00_TRN_284_TRN_284 00_TRN_284_TRN_284 3/7/133:00PMPage26 26 TR NEWS 284 JANUARY–FEBRUARY 2013 Research Center) International Arctic Larry Hinzman, permafrost. (Source: frequency anddepthof Alaska, showingthe FIGURE 1Transect of structures. can bedisastrousbelow leave largevoids,which earth; thethawedwedges repeated crackinginthe wedges formedby frost oftencontainsice on theNorthSlope;perma Ice wedgeinpermafrost - process. easy toidentify, classificationisamore complex built above. earth, whichbecomedisastrous foranystructures the earth. Thethawedwedgesleavelarge voidsinthe contain icewedges,formedbyrepeated crackingin freezes. concentrated nearthesurface ofeachsoillayerasit The icestructure isdistinct,withtheicefeatures Depth (m) Although thesetwotypesofpermafrost are fairly Both epigeneticandsyngeneticpermafrost may 800 600 400 200 0 72° Ocean Arctic Bay Prudhoe Permafrost Continuous 70° Range Brooks 68° Treeline Lake Discontinuous

66°

E N I , K M : P NGINEERING ORTHERN OF NSTITUTE ANEVSKIY IKHAIL HOTO Latitude (N) River Yukon ture content. in granularsoilsorsiltsandsandswithlowmois- engineers. Thaw-stablepermafrost typicallyisfound strength asitthawsandgenerallyisnotaproblem for define permafrost byhowitperforms whenitthaws: performance, temperature, andfrequency—and Engineers classifypermafrost bythree attributes— Classifying Permafrost ing onthelocation. syngenetic permafrost canbewarmorcold,depend- ing willmeltthepermafrost. Bothepigeneticand of thepermafrost is31.5ºF. Intheseareas, anywarm- 31ºF. Insouthern Alaska’s CopperRiverBasin,much Fairbanks area incentralAlaskaisapproximately Territory. Theaveragepermafrost temperature inthe connect Fairbanks,Anchorage,andCanada’s Yukon the Elliott,Richardson, andParksHighwaysthat is foundsouthoftheYukon River, thelocationsof permafrost isbelow30ºF. Warm permafrost typically warm permafrost isbetween30ºFand32ºF, andcold ble, becausethelayersconsistofsilts. Syngenetic permafrost isalmostalwaysthawunsta- unstable, dependingonthecontent—gravelsorsilts. Epigenetic permafrost mayornotbethaw ice-rich siltsandsands,icewedges,frozen . strength withthawing;yedomaisanexample,asare u u Construction almostalwaysleadstowarming. Permafrost alsoisclassifiedbytemperature— Fairbanks Thaw-unstable permafrost Thaw-stable permafrost 50 to60m maximum 64° Range Alaska Sporadic 62° retains mostofits loses almostallofits Anchorage 60° Ocean Pacific 58° TR NEWS 284 JANUARY–FEBRUARY 2013 27 Alaska’s western shoreline Alaska’s Newtok, in 2008, near quick erosion showing the relocation of that led to the village. The greatest and most costly impacts of warming and most costly impacts of The greatest degradation As climate warms, permafrost road problematic Thermal modeling of Alaska’s is a pri- erosion climate-related In coastal regions, appear in the transition zones between warm and appear in the transition zones between to erosion. prone and in coastal areas cold permafrost infrastructure transportation Alaska’s In these areas, is pre- is most fragile; because the transition zone are dominately yedoma, the impacts of thawing severe. and becomes a challenge for embankment designers show how The transition areas maintenance crews. cold to warm may transform from permafrost periods. or reconstruction between rehabilitation transfer have and advective heat Groundwater degradation below permafrost affected increasingly shows that embankments. In addition, research tables accel- flow along the permafrost groundwater monitor the sub- degradation. To erates permafrost thermal dynamics requires tleties of the subsurface imaging and modeling technology. ther- embankment configurations has led to more mally stable embankment designs. The design strate- the thawing of ice-rich gies seek to reduce and Modeling also assists researchers permafrost. temperatures engineers in exploring how surface roadway below the stability of permafrost affect embankment designs embankments. The improved maintenance and mitigation costs dra- have reduced matically. The U.S. Army Corps of Engineers iden- mary threat. in 180 Alaska communities. In threats tified erosion western village of Newtok on Alaska’s the Yupik swallowed the dump site, erosion shoreline shore, The vil- landing, and other infrastructure. the barge on an island to higher ground lage is being relocated at an estimated cost of $130 million, 8 miles away, a new roadway, facility, which includes a new barge permafrost contains areas with contains areas permafrost permafrost appears in areas that are appears in areas permafrost permafrost is found in isolated areas. permafrost Discontinuous Continuous Sporadic In contrast, cold permafrost, like that typically like that In contrast, cold permafrost, by its fre- engineers classify permafrost Finally, After classifying the permafrost at a location, engi- After classifying the permafrost u u u

Permafrost Design Challenges Permafrost design typically encounters difficulties Permafrost and the or moisture, with changes in temperatures long term. Engineers must decide whether costs are cold or to adopt another strat- to keep the permafrost and accept Often, the choice is to move forward egy. maintenance costs. the increased Building a roadway over the permafrost, for example, over the permafrost, Building a roadway to cause melt- enough often raises the temperature also accelerates in air temperature ing. An increase thawing. Although 27ºF. Slope, is around found on the North found to the only slightly colder than permafrost dramatically of difference south, the few degrees a buffer provide of the ice and the strength increase against a warming climate. quency at a given location—sporadic, discontinu- ous, or continuous: completely frozen year-round. The graphic in Figure year-round. completely frozen 1 (page 26) indicates the distribution of permafrost in Alaska. Sporadic and discontinuous permafrost— almost always whether epigenetic or syngenetic—are warm permafrost. neers derive any number of combinations to describe it. The descriptions help engineers make categorical distinctions to facilitate adaptive designs. and without permafrost. Glacier National Park in Montana, for example, has Glacier National Park in Montana, for example, many examples of sporadic, warm permafrost.

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PHOTO: ANNA LILJEDAHL, UNIVERSITY OF ALASKA FAIRBANKS TABLE 1AdaptingDesignstoPermafrost ing climate. adapt designstoachang- and inotherregions on Alaska’s NorthSlope transportation corridors planners chartingnew hydrologic forceshelp precipitation, andother on snowmelt,riverflow, remote location;findings measurements ata Researchers recordglacial hwprars Whenpermafrostiswarmandsporadic;designersantici- Thaw permafrost eoeadrpaeWhenpermafrostisshallow, orthethicknesslayeris Remove andreplace Thermal design Keep frozen Design Option Consider Using structure; permafrostissporadic pate warming;permafrostisthawstable perature isbelow30ºF;permafrostthawstable of thaw-stablepermafrost;project involvescriticalinfra- low; thinlayerofthaw-unstable permafrost sitsontop When foundationmovementisunacceptable When warmingisnotlikelytooccur;permafrosttem- be appropriate forthenext30.Forexample,ifper- ning anddecisionsmadeinthepast30yearsmaynot beginnings ofthelasticeage. a deeperandperhaps longerPDO,similartothe cooling trend beyondpastcycles(4 PDO willbeshorter butwilllowerthedepthof begun adrop intemperatures. temperatures, andthenextcycleinPDOhas last changeoccurred inthemid-1970s,withhigh cooling trends inAlaskaona30-yearcycle(4 and AtlanticOceancurrents willcausewarmingand Oscillation (PDO)indicatesthatchangesinPacific and short-term coolingtrends. ThePacificDecadal dict thatparts oftheglobewillexperiencebothlong- address theseissues. trends, forexample,complicatetheforecasting to remain. Decade-to-decadewarmingandcooling As research explores theseissues,manyquestions Uncertain Predictions $23 billion. ing all180threatened communitiescouldexceed and anewairport. Thecostofrelocating orprotect- This uncertainty causesadilemma,astheplan- Some climatologistsmaintainthattheupcoming Despite risingtemperatures, climatemodelspre- ). Otherspredict ). The permafrost frozen makessense. peratures willremain thesameorlower, keepingthe depends onthepredicted temperatures. If thetem- quently, thedecisiontokeeppermafrost frozen ture ofthepermafrost isslightlycolder. Conse- in areas ofdiscontinuouspermafrost, the tempera- of thepermafrost rangesbetween30ºFand32ºF, but generally maynotprove ashelpful.Thetemperature tinuous, warmthaw, andunstable,awarmingclimate impacts ofthawingpermafrost oninfrastructure. term byeliminatingthesporadicpermafrost andthe this case,awarmingclimatemayhelpinthelong the snowinsulatesagainstcoldwinterair(5 these roadways stayatapproximately 6ºF, because mafrost. Research hasshownthatthesideslopesof likely towarmtheground enoughtomelttheper- frozen isnotagoodoption,becausethestructure is of sporadicpermafrost, keepingthepermafrost roadway, bridge,building,orembankment.Inareas ing—leading tostructuraldamage,whethera Thaw-unstable permafrost losesstrength withthaw- ful, dependingontheclassofpermafrost. left) illustratesthekindsofdesignsthatcanbeuse- plexity; classificationhelpstoclarify. Table 1(below compounded bypermafrost’s ambiguityandcom- variation—that is,forfreezing andthawing;or engineer hasseveraldesignoptions: can focusontheremaining classesofpermafrost. An not poseathreat untilextreme warming,solutions lematic designchallenges,andcoldpermafrost does permafrost typicallydoesnotproduce themostprob- the possibledesignstrategies.Becausethaw-stable mafrost willdetermineitsengineeringproperties and Specific casesillustratethattheformationofper- Permafrost DesignStrategies will likelycausethawing,even withoutclimate warming causedbytheconstruction ofaroadway Keeping permafrost cold, however, isexpensive. The Preserving Permafrost how itbehaves. lenges willstemfrom permafrost—what itisand the associatedtransportation infrastructure chal- design challengeswillarise?Nevertheless, manyof mafrost thawingreverses, whatnewandunseen u u u u In areas withpermafrost categorizedas discon- Many considerationsinfluencedesignchoices. All oftheseoptionsare expensive.Thechoiceis Remove andreplace thefrozen soil. Design thestructure foranticipatedthermal Thaw thepermafrost; Keep thepermafrost frozen; ). In TR NEWS 284 JANUARY–FEBRUARY 2013 29 A research team prepares A research river gauging to conduct hydrologic for a major new North study for the Slope transportation corri- dor; understanding the of flow rates, sedi- effects annual ment transfer, and ice floes on runoff, potential river crossing sites is a key issue. Ther- . U.S. , Janu- Fourth . Final Report, Permafrost. Permafrost. . Final Report, Institute of North- . Final Report, Fairbanks Daily News Miner . Final Report, Alaska Department of Trans- Alaska Department . Final Report, Insulation Performance Beneath Roads and Air- Insulation Performance , Vol. 18, 2005. , Vol. ary 30, 2011. Pacific Climate Shift in the Climatology of Alaska. Journal of Climate Roadway Construction over Permafrost. International Conference Proceedings, National Academy Proceedings, International Conference D.C., 1983. Washington, Press, fields in Alaska and Public Facilities, December 1986. portation Convection Embankments University Center, Research ern Engineering, Transportation of Alaska, Fairbanks, September 1994. mosyphon Cooling of Chena Hot Springs Road Engineering, University of Alaska, Institute of Northern Fairbanks, February 2003. Alaska. Anchorage Daily News, February 25, 2011. Global Climate Change Impacts in the United States 2009. Program, Global Change Research Villages. Infrastructure, 4. The Significance of the 1976 B. and G. Wendler. Hartmann, 5. for Esch, D. C. Evaluation of Experimental Design Features 6. Esch, D. C. 7. Roadway Stabilization Using Air Kumar. Goering, D., and P. 8. Forsström, A., E. Long, J. Zarling, and S. Knutsson. Adapting to Change on infra- Although the impact of climate change than in other in Alaska severe is more structure lessons for Alaska demonstrates important regions, warming engineers and planners in adapting to both the This entails addressing and cooling trends. thermal and gaps in knowledge through emerging integrating the find- and then research hydrological designs. robust ings into new and more References 1. in Interior Child Discovered C. Remains of Ice-Age Grove, 2. 3. Rettig, M. Alaska Seeing Impact of Climate Change in Its structures. Consequently, the best alternative is to the best Consequently, structures. cold. keep this type of permafrost ). ). ). Air ducts apply the chimney effect—a hori- Air ducts apply the chimney effect—a Air convective embankments consist of uni- Air convective embankments consist of Thermosyphons, like those used on the Trans- Insulation typically is placed 3 feet below the Insulation typically is placed 3 feet below The most common methods to keep permafrost Continuous thaw, unstable, cold permafrost is unstable, cold permafrost Continuous thaw, u u u u

cold include insulation, air convective embank- cold include insulation, air convective ments, thermosyphons, and air duct systems: change. In most cases, because of the cost, engineers change. In most cases, because of the cost, and use of thawing permafrost accept the effects areas. annual maintenance to level and patch these thawing, so climate change accelerates Consequently, into moves northward that discontinuous permafrost dominated by cold continuous permafrost. areas zontal pipe laid in the roadway slopes is equipped zontal pipe laid in the roadway chimney at the outlet. with a vertical because it will not melt in generally not a problem, the near term or eventually become discontinuous, Climate warming is not likely to warm permafrost. of road- have a significant impact on the performance because areas, ways and bridges in cold permafrost climate changes will not melt the per- the predicted of the roadway within the life sufficiently mafrost formly sized rocks stacked up. Convective cells are stacked up. Convective formly sized rocks winter and cool during the within the rocks created below (7 the permafrost heat during the win- ground Alaska Pipeline, remove ter by turning a liquid into gas inside a pressurized tube. The gas rises to the top of the tube, releasing the liquid con- heat into the cold air above ground; densate then falls back to the bottom of the tube (8 road surface to reduce the heat going into the per- to reduce surface road (6 mafrost

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