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TheRemoteMonitoringofAvalancheActivity
G.Statham1,A.Wilson2,J.Kelly3,andR.Bilak4
Alpine Specialist, Canmore, Alberta,Canada.
2 The University ofCalgary,2500 University Drive NW., Calgary, Alberta, Canada. T2N 1N4
3 SRAWS, Glacier National Park, British Columbia, Canada
4 Mountain Watch Inc. Suite 900,840 7t hAvenue SW., Calgary, Alberta, Canada.
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ABSTRACT
Observing and recording avalanche activityis one of the
mostimportant factors when assessing snow stability and
preparing aforecast.Thisinformationiscritical forthe
optimumtiming of road closures,explosives control and
reopening of avalanche zones.Observing this avalanche
activity can bea problem as it requires manpower andtime.
Inremoteareas oroperationswithnumerousavalanche
paths,thiscanbeimpracticalifnotimpossible.Poor
visibilityordarknesscanalsohindertheaccurate
assessment ofavalanche control results.
The following paper outlines a two yearproject aimed
at developinga remote system of avalanchedetectionwhich
will provide down avalanche information in real time.
INTRODUCTION
The Trans Canada Highway is the main artery forvehicle
trafficthroughtheWesternCanadianmountains.Forty
kilometers of this road travels through Rogers Pass, where
134 separate avalanchepathswith multiple starting zones
affect the route.Temporary road closuresare frequenthere
duringthewinter months, eachoneaffectingthecommerce
of several provinces.It has been estimated that a typical
two hourclosure will result in $50 000 of direct costs to
stopped vehicles alone (Morrall, 1992).
The needfor a remote telemetry system indicatingdown
avalanches and hopefully streamlining the timing of road
closureswasexpressedin1994bytheSnowResearch
Avalanche Warning Section (SRAWS) in Rogers Pass, BC.
Overthe winters1994/95and95/96,the authorsunder-
tooka project to develop a technology which would give
realtimeindicationofavalancheactivity,bedurable
enough towithstandimpact forces,wouldreset itselfto
monitor multiple cyclic events throughout the season and
require minimal maintenance.
The system wasbuilt by MountainWatchInc. andnamed
theAvalancheTrack MonitoringSystem(ATMS).The
ATMS was installed in Cougar Corner #6 (CC#6) at Rogers
Pass, an indicator path where conditionsare consideredto
berepresentativeofthesnowstabilityinsurrounding
terrain.The information obtained was then used in com-
binationwithotherstandardforecastingparametersto
produce stability evaluations and forecasts.
*Working on contract to Mountain WatchInc.
METHODOLOGY
The sensorwas located high in the track of the avalanche
path.Itwas suspended bya cable which hung froman
aerial line tensioned 10 meters high between mature trees
on either side of the track. This suspension cable could be
raised orlowered to account forthe potential buildup of
avalanchedebris.A two strandsignalwirewas intertwined
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with the 1/8 inch steel suspension cable,connecting the
sensorwith a Campbell Scientific CR10datalogger and a
radio located safely to the side of the track.
Thesensorwas a PVCencased onepiece mechanical
accelerometer with a weighted1.5 meter PVC type 1 wand
attached underneath.The accelerometer measured snow
movements bythe deflections ofangle off vertical of the
suspended wand.Avalanches strikingthewand would
deflect the sensor beyond a predeterminedangle, thus trig-
geringan alarm. The signal was generatedas a dry contact
closure andsent to the datalogger/radiovia the signal wire.
The alarm was a 15second tone transmission on a radio
frequency and a time/date print within the datalogger.
Deflections weremonitored in the downslope axis only.
An adjustable switch was used to set the optimum angle of
trigger forthat particular site.Options were 30,60 or90
degrees off vertical,which would prevent site dependent
variables such as wind gusts from triggering the alarm.
Asignalconditionermodulewaslocatedatthe
datalogger/radio site.Thisfunctionedindetectingthe
switch closure at the sensor,flagging this event within the
datalogger and then powering up the radio transmitterto
sendanalarmtone.Thedataloggerwasusedonlyfor
research purposes to confirm exact avalanchetimes.The
sensorand signal conditionerrequired no powerof their
owntooperateinthesleepmode.Theentiresystem
derived it's excitation powerfrom the load carried in the
datalogger/radio to flag avalancheevents.This was a 12v
battery and was continuously available to the signal con-
ditionersince an event may happenat any time.
RESULTS
ThefirstinstallationofthissensoroccurredonJanuary
21, 1995.The angle of deflection was set at 60 degreesand
the base ofthe wand was approximately 2meters above
theground.DuringthenextavalanchecycleCC#6
producedtwo avalanches, the second of the two being the
largest.Thesensorindicatedonlythelargeravalanche.
Subsequent to this, the angle of deflection was changedto
30 degrees andthewandheightlowered to 1.5 meters above
thegroundinthe hopesofnotmissingthe smaller,but
equally important events.
Twomore significantavalanchecyclesoccurredthatsea-
son,withCC#6producing atotalof6moreavalanches,
rangingfrom size 1 to 3.The sensor indicated eachevent,
and in one instance awoke the Forecaster during the night
whowasanticipating thecycle and had setvariousclo-
sure parameters before going home.
Based on the successful results of the first season, CC#6
wasagaininstrumentedforthe1995/96winterseason.
Results from this winterwere variable,with several prob-
lems beingidentifiedandcorrected. Durabilitywas anissue
as a large avalanche early in the season snapped the PVC
wand in half and rippedapart one of the connectors in the
signalwire.Thiswasrepaired,but soonafterthe radio
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