Planning Avalanche Defence Works for the Trans-Canada Highway at Rogers Pass, B.C. Schaerer, P

Planning Avalanche Defence Works for the Trans-Canada Highway at Rogers Pass, B.C. Schaerer, P

NRC Publications Archive Archives des publications du CNRC Planning avalanche defence works for the Trans-Canada Highway at Rogers Pass, B.C. Schaerer, P. A. This publication could be one of several versions: author’s original, accepted manuscript or the publisher’s version. / La version de cette publication peut être l’une des suivantes : la version prépublication de l’auteur, la version acceptée du manuscrit ou la version de l’éditeur. Publisher’s version / Version de l'éditeur: Engineering Journal, 45, 3, pp. 31-38, 1962-05-01 NRC Publications Record / Notice d'Archives des publications de CNRC: https://nrc-publications.canada.ca/eng/view/object/?id=aa939b6c-659a-4f88-b6d4-3c009044f55e https://publications-cnrc.canada.ca/fra/voir/objet/?id=aa939b6c-659a-4f88-b6d4-3c009044f55e Access and use of this website and the material on it are subject to the Terms and Conditions set forth at https://nrc-publications.canada.ca/eng/copyright READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE. L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site https://publications-cnrc.canada.ca/fra/droits LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB. Questions? Contact the NRC Publications Archive team at [email protected]. If you wish to email the authors directly, please see the first page of the publication for their contact information. Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n’arrivez pas à les repérer, communiquez avec nous à [email protected]. ser TH1 OGERS PASS, B. C. 11113III 1809002IIIII 11 I~~!~IIII 095 IIII~IIII 2 IIIIII This is a joint paper of @he Departmenst of Public Works and the National Research Council. REPRINTED FROM THE ENGINEERING JOURNAL, VOL. 45, NO. 3, MARCH 1962, P.P. 31-38 RESEARCH PAPER NO. 152 OF THE DIVISION OF BUILDING RESEARCH PRICE 25 CENTS OTTAWA NRC 6732 MAY 1962 % -- This publication is being distributed by the Division of Building Re- search of the National Research Council. It should not be reproduced in whole or in part, without permission of the original publisher. The Division would be glad to be of assistance in obtaining such permission. Publications of the Division of Building Research may be obtained by mail- ing the appropriate remittance, (a Bank, Express, or Post Ofice Money Order or a cheque made payable at par in Ottawa, to the Receiver General of Canada, credit National Research Council) to the National Research Council, Ottawa. Stamps are not acceptable. A coupon system has been introduced to make payments for publications relatively simple. Coupons are available in denominations of 5, 25 and 50 cents, and may be obtained by making a remittance as indicated above. These coupons may be used for the purchase of all National Research Council publica- tions including specifications of the Canadian Government Specifications Board. sion of Building Research, National Research Council, Ottawa, Canada. 4 VALANCHE DEFENCE For The Trans-Canada Highway T ROGERS PASS, B.C. P. A. Schaerer Former Research Officer, Snow and Ice Section, Division of Building Research, Niltion01 Research Coc~ncil,Ottawa SELKIRK Mountain range in for the first railway link between of Canada, which is responsible for e interior of British Columbia Eastern Canada and the Pacific Coast. the construction of the Trans-Canlada ne of the major obstacles to be It was in use from 1885 until 1916 Highway through Glacier National the Trans-Canada High- when the Connaught tunnel was built Park, began reconnaissance work f way. Various routes through this and the railway line (through the Pass the highway and organized a prel range have been investigated; that was albandoned. inary survey of avalanche sites an through Rogers Pass was se1ected.l It was known that lavalanches avalanche activity. These avalanch The pass lies 'between the towns of would be one of the major problems observations were under rhe directio Golden and Revelstoke in Glacier for any road built through the Sel- of N. C. Gardner. In 1956 an ava- National Park and was chosen by the kirk range (Fig. l). Accordingly, in lanche observation station was estab- Canadian Pacific Railway as rhe route 1953 the Department of Public Works lished to carry out the more detailed search, co-operated in thc organizn- tion of the avalanche observ:~tion st'?- tion. Bet\\reen 1957 '1ncl 1960 thc a:ithor was in chargc of this st~t~on and was responsible lor p1.1nning the aval~lnche defence. This pqcr tl:,- scribes in brief rhe obscrvatlo~ls\vhich were m,lde 2nd summ'lrucs the dc- fence \vhlch was chosen. Terrain The summit of Rogers Pass is 4,300 ft. above se,a level, and t!::. pealts of the Selkirk range risc to 11,000 St. Tlic vallcys ;~ssocinteil\\lii-i~ the Pass are short and comparative-I? steep on the east side, but risc Lo the summit with a g~lilclual climb from Figure 2: Bear Creelc valley on the east side of Rogers Pass. Part of the highway the west. A typical Selkirk valley is can be seen in the left foreground. narrow ancl has steep sides (Figs. 2, 3). The mount~~insides on the Rogers PASSroute have a terrace located be- the river \\dlich flows through the snowfall is usually f0110~r:clby one or tween 5,500 and 6,500 ft. labove sea valley. The lower mountain sides and several d~yswit11 only light snowfall. level (Figs. 4, 5). The terrace goes valle!is are covered with heavy timber During winters of light snowfall three ' gradually over into the scree slopes and clei~sebrush. Trees become scat- storms may occur yielding more than and rockfaces which rise to the moun- terecl on the terrace, leaving space for 16 in. of snow in a three-day period, tdin ridges. Below the tcrrace a sharp alpine meaclows. but during winters of heavy snowfall clrop over cliffs lcacls to talus slopes 10 such sto~msmay occur. Only occa- ancl alluvial fans into the valley bot- Climate sionally, labout once in fhree years, tom \vhich is between 300 ancl 1,000 is there a silowstorm that contributes Rogeis Pass is in thc region popu- more than 36 in. in a three-day peri- Et. wicle. In some plaees the mountain larly kno\vn as the interior wet belt sides are close together, resulting in a od. Most s~lowfallsare accompanied of British Columbia.' High annual by wind which deposits large amounts narrow V-shapecl valley. The highway ~recipitationand heavy snowfall are is cut into the talus slopes and alluvi- of snow on the lee side of the moun- its most distinctive features. The aver- tain ridges. The mlaximum depth of al fans, ancl except tor two short sec- age annual precipitation, measured be- tions is located on the north sicle of snow on the ground in the valley is tween 1921 and 1950, at Glacier close about 100 in., and on the mountain, to the summit of Rogers Pass, is 18 at the 6,700-ft. level, the greatest in. of rain ancl 342 in. of snow, while measured depth of 160 in. was ob- the maximum annual snowfall ever served on May 1, 1959. Figure 3: Illecillewaet valley on the west observed \\.as 680 in., measured dur- Temperature during a snowstorm nor- side of Rogers Pass. The avalanclle sites ing thc winter 1953-54. The magni- mally i>anges bet\veen 20 and 32°F. are the open paths on both sides of the tude ancl frequency of the 24-hour valley. After the storm has ended, it is usual sno\vfalls at Glacier cluring the win- for cloudy weather to continue and ters bet\veen 1953 ancl 1960 are the temperature to change relatively show^^ in Tn:ble I. slo~vlv. Frenuentlv., , however. the Storms \\-it11 '1 high rate of snowfall temperature rises during a sno\vstolm are not frequcnt ancl are usually of ancl the snowfall in the valleys short duration. A day \\-it11 hcavy changes to rain. Tlle temperature falls TABLE I Frecluency of Snowfalls at Glacie~ Tolal Nzor~ber0.i (lags with m~owl'alls snv~ql'all jor llre Less than winter, I [:int,er 4 fn. to 1 I 19 lo 20 i.n. 80 in. .in.. -- - 195sj39. .......: s5 4 1 3 - 442 1959/60. ........ 8-1 29 1 - 368 '%Therecol.ds of the wintcr 195-4/55 inclutlc trnlg tllc srlon.fi~llsafter 1 Jar1un1.y1955. below 0°F only a few times during who kindly made available their rec- the winter and this cold weather USII- ords on all avalanches that had af- ally does not coi~tinuefor more than fected railway operation during the a week. period 1910 to 1952. In 1960, when the final plans were Avalanche Survey developed for the first stage of clc- The avalanche survey had to fence, there were available detailed produce the following informatiol~ observations of avalanche activity about the aveilage and very large during seven winters ancl partial ob- avalanches that occur at each site: servations from ano'thel. 40 years. their rupture zone, path ancl terminus; Records of avalanches that occr~rred their depth and width; during the years before 1953 rc- their frequency of occurrence; vealed that therc were periods of more the prevailing conditions responsil)lc than one year in whicll avalanche ac- for thcir occurrence. tivity was a maxiurn.

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