DEPARTMENT OF THE INTERIOR
THE ALASKA RAILROAD
WINTER OPERATING CONDITIONS ON THE ALASKA RAILROAD
In order to describe winter operating conditions on The Alaska Railroad it
is necessary first to outline the overall location of the line, then give a
topographic description, and finally outline the prevailing weather conditions of the various sections through which it passes from tidewater to the interior of Alaska.
From its southern terminus, the town of Seward (Mile Post 0.0) on Resurrection
Bay, an all-year-round ice-free port on the northern shoreline of the
Pacific Ocean, the Railroad extends northward for 64.2 miles through the steep mountainous area of the Kenai Peninsula to Portage, which station is located at the east end of Turnagain Arm, one of the branches of Cook Inlet that is ice-bound and unnavigable from November to May. Portage (MP 64.2) is the junction point of a 12.2 mile branch line from Whittier, which is also an all-year-round ice-free port. This 12 mile branch passes through two long tunnels that pierce the mountain range which forms the neck of the Kenai Peninsula.
From Portage the line follows the rock-bound shoreline of Turnagain Arm for 50 miles to the City of Anchorage (MP 114.3) located on the shoreline of Knik Arm, another branch of Cook Inlet, where headquarters offices and repair shops etc, of The Alaska Railroad are located.
From Anchorage the line follows the shoreline of Knik Arm in an easterly direction and crosses around the extreme end of same at Matanuska (MP 150.7), where the line then turns northward into broad Susitna River Valley and extends up same to Canyon (MP 268.4).
The Susitna River and its tributaries drain the south slope of Mt. McKinley.
From Canyon the line rises over and through the Broad Pass, elevation 2,363 ft., the lowest and widest pass in the backbone range of the North American Continent. From Summit (MP 312.5) the line descends to Healy (MP 358.1) located on one of the tributaries of the Yukon River. From Healy to Fairbanks (MP 470.3) the line is in the broad Yukon Valley. It crosses the Tanana River at Nenana (MP 411.7) on one of the longest single span bridges yet built for railroad traffic. Fairbanks is normally considered the northern terminus of the line, though a branch line extends 27.2 miles southward from this terminus to Eielson Air Force Base, totaling almost 500 miles of main line railroad extending in a north and south line from the warm waters of the Pacific Ocean to the sub-arctic and permafrost areas of the Yukon Valley.
It must be realized that on such a length of line between these two extremes, varying climatic and railroad operating conditions of all types prevail, and that no general description of them can be made Seward has a climatic condition similar to Boston; Anchorage, one similar to St. Paul; and Fairbanks, one that cannot be compared with any other location.
In the mountainous areas south of Portage our snow depth indicators often show from 10 to 15 feet of snowfall on the ground. Rotary snowplows propelled by two locomotives have to be kept in constant use from December to April to keep the tracks free of snow in this location. Slight wind storms soon fill up the trench made by the rotaries and block the trains. Warm spells causing partial thaws loosen the snow on the mountains and cause it to slide and bury the railroad line below.
Some snow slides follow the same course each winter. At some such locations huge snow sheds anchored into the mountain side carry the avalanches over the tracks. During the past 10 years, line changes have been made to by-pass the worst of the chronic slide problems, At other locations where the slide patterns are erratic, bulldozers and special spreaders have to be kept in readiness to clear the tracks. Some slides gather trees and loose rocks that happen to be in their paths and deposit the mass in huge piles on the tracks. Such slides cannot be removed with the rotaries as their fast whirling blades are easily broken by any solid matter such as wood or stones. At such locations the modern D-8 bulldozer has been found the best snow clearing machine. Prior to the advent of bulldozers, snowslides that contained rock and trees were removed with hand tools and explosives. In the old days, from 1916 to 1935, it was no uncommon sight to see gangs of 100 men or more removing these types of avalanches from the tracks with picks and shovels.
Another hazard, one that is more bothersome than the removal of snowfalls, drifts and slides, is the formation of ice from bank seepages where the line follows a bench cut along the top of a mountain. Even small creeks during long cold spells will freeze up and form solid ice on the tracks overnight.
The temperature of normal flowing water, even spring water, along The Alaska Railroad varies from only one to three degrees above freezing. Such low temperature water readily turns to ice. Normal section maintenance crews have to be reinforced with extra help in areas where such icing conditions occur. In tunnels where water drips from the roof and oozes from the sides, gangs of men have to be on hand to remove the huge icicles and wall deposits of ice before the passage of each train. Some tunnel-ends south of Portage are equipped with huge doors, and a steam plant 1ocated just outside of the portal has to be maintained and operated all winter to keep down the icing conditions that occur in these tunnels. Watchmen and steam plant operators have to be on hand and ever on the alert day and night to open the doors for the passage of trains and keep up the steam in the heating plants. Along the wind-swept shoreline of Turnagain Arm, where the winter temperatures vary from 0 degrees to 30 degrees below, constant patrols are made before each train is allowed to proceed. Some trains, because of delay or where a patrolman overlooked the formation of ice on the tracks, have been wrecked by this fast icing. During the extreme cold spells that are often of a month's duration, the track maintenance forces are beset by this icing. When the warm spells occur, the snow from the steep mountain slopes slides onto the tracks. There is no happy medium.
Another winter hazard, and one that is generally associated with erratic snow slides, is the breaking down of the poles and towers of the telephone and telegraph lines by avalanches, thereby disrupting communications and causing expensive delays. Most of the known slide locations have been avoided by building long spans, but in areas where the slide paths are erratic, the location of such supporting poles and towers is not possible. South of Broad Pass warm air drifts in from the Pacific Ocean causing what is commonly called a "silver thaw". Snow passing through a thin layer of warm air that lies close to the ground falls in globlets of liquid ice that adhere to everything instantaneously. When such silver thaws occur, the telephone and telegraph wires soon get so loaded with ice that the supporting cross arms and poles break clown. Miles of T & T lines have been wrecked on numerous occasions by such wire icing even though double and triple the normal number of poles have been put up to avoid such occurrences.
To combat these conditions our Communications people have increasingly turned to the use of radio. Fifty miles of our pole lead has been completely replaced by a microwave system. This system is inherently free of damage by icing conditions and low temperatures. It is probable that in future years there will be quite an increase in this system.
Between Anchorage and Canyon, at the south entrance to the Broad Pass, the average snowfall varies between 2 to 5 feet; and temperatures range from 0 to 50 degrees below. This section of line is almost free from constant winter winds, though there are short stretches where funnel winds coming through a gap in the adjacent mountains cause snow drifts, and of course train blockages. This section is generally kept clear by the use of locomotive propelled V-type snow spreaders. This method of snow clearing in this section has been found to be the fastest and least expensive. The Alaska Railroad is currently preparing experimental use of aircraft jet engines for some snow removal problems.
Another hazard to winter train operations on The Alaska Railroad has developed with the increase of the Moose herds. These wild animals, some of them weighing 1200 pounds, get onto the snow cleared railroad tracks and refuse to leave them on the approach of trains. It is assumed that the Moose, whose prime enemy is the wolf gets the impression that the big snorting locomotive is of the same breed and that his only chance to get away from such a ferocious wolf is to outrun him where the running is good. Mr. Moose knows from long experience with wolves that if he gets into deep snow where his leg action is hindered, he is playing into the wolf's hand, so he naturally tries to outrun him in the area clear of snow where he has a chance to use his feet. Numerous attempts without results have been made to give the Moose escape paths by bulldozing runoffs through the adjacent snow banks. Bridge decks have been covered over with metal plates to prevent the Moose from getting their legs down between the bridge ties. Such in seem only to lengthen the chase. During the past winter over 350 Moose were killed by Alaska Railroad trains and no end of expensive delays and traffic interruptions were caused by these animals. It is not possible to fence them out. Ranchers in the Matanuska Valley state the Moose are totally oblivious to the highest barbed wire or metal fences. They invariably walk right through them.
Associated with track maintenance at this latitude (60° to 65° N) is the expansion of the ground caused by the deep penetration of frost commonly called "frost heaving". The average annual penetration of normal winter frost where the top of the ground is semi-insulated with grass, leaves and loose snow, is generally to a depth of 2 to 3 feet; but where the snow has been removed or compacted, the frost goes down to depths of 5 and 10 feet, depending on the structure of the sub-deposits. The deep penetration of frost, plus the varying geological formations under the tracks, and the consequent expansion of the ground below in proportion to its water content; causes the frost heaves to buckle and bend the level lay of the rails into irregular humps and heaves. To correct these heaves and make it safe for the passage of trains, wood shims are inserted between the base of the rail and ties. Track heaving invariably occurs during the long cold spells and maintenance crews have to "shim up" the rails in semi-darkness sometimes in 50 degrees below zero weather to make the track operable, It is no uncommon sight to find at the end of a severe winter stretches of shimmed track a half-mile or more in length, some of the shims being 6 to 8 inches high, the rails in such shimmed sections being held to line and gage by numerous tie rods or bridles. Shimming work is a most disheartening task, as the heaving and buckling of the tracks, also its settlement when thawing out, is forever changing. Shimming crews will level up a stretch of track one day only to discover the following day that more heaving has occurred during the night which necessitates the entire changing and extension of yesterday's work.
Closely allied with track heaving and distortion of the rolling surface of the rails is the lifting effect deep frost has on bridge abutments and pilings. Although every attempt is made during construction to get the foundations of bridge piers, piling bents arid abutments into the ground as far as possible, the process of frost penetration, plus frost adhesion, lifts them out. When the first frost comes, it forms a top crust that unites with the piers or piling. As the crust gets thicker and the freezing ground below it expands upward the crust attached to the piling or concrete structure has such gripping power that the bridge bents and abutments are lifted off their original foundations and the bridge surface distorted. Single piling and T & T poles set in ground that freezes to any great depth are lifted up out of the ground from 4 to 6 inches annually. In many areas it has been found necessary to erect pole tripods instead of setting telephone and telegraph poles in deep holes, as the frost heaving does not affect the tripod which is toed into the ground only a slight amount, while the deep set pole on which the frost can get a grip is eventually pulled out of its setting.
Precaution against the same effect of frost heaving on concrete building foundations where the back filling of soft soils or clay would adhere to the concrete has to be avoided by placing a vertical section of screened gravel aggregate between the adhesive soil and the wall; thereby creating a friction zone between the heaving ground and the concrete.
Through the Broad Pass, which on account of its width and low elevation acts as a spillway for the heavy cold masses of air that accumulate in the Yukon Valley, the periodic winds that blow in this section drift the snow in long ridges and deep drifts. Winter temperature ranges from 10 degrees to 60 degrees below in this section. Spreader type plows have to be operated almost constantly during most of the winter to keep the tracks through the pass open, Even small drifts, 8 to 10 inches deep, if allowed to remain on the tracks, soon become almost as hard as solid ice. Small pellets of snow as they are jostled and blown around by the wind collect static electricity, When these small electrified pellets are drifted along, some of them find catch places and immediately weld themselves to the mass below and around theme Heavy engines have been derailed and damaged by such hard drifts that appear so small and of no consequence.,
The upper part of this section of line between MP 343.0 and Healy (MP 358.1) is over part permafrost foundations in the Nenana River Canyon. The removal of the already thawed gravel and glacial deposits and the consequent alteration of the natural or old drainage channels during the construction of the line has created new thaw areas especially in the gumbo-filled hollows, thereby causing long sections of the subgrade to settle and slide toward the river. Numerous unsuccessful attempts have been made to stop this thawing and sliding. Large maintenance crews are continually employed there jacking up and back filling the tracks on these settling sections.
From Healy to Fairbanks, where the winter temperature sometimes reaches 70 degrees below zero, and 25 degrees below zero is considered a fairly warm day, the line passes through rolling valley country most sections of which are underlaid with permafrost and ice lenses. The average depth of summer thaw is only a few feet; consequently, embankments of gravel or earth placed on top of these permanently frozen areas are always settling during the hot summer season when the thermometer climbs to plus 98 degrees or better.
The gravel ballast and embakments warm up under the almost constant summer sun and act like hot pokers placed on top of ice cakes. Hundreds of thousands of cubic yards of backfilling and grade raising material have been used and the settlement of the tracks partially stopped in this section Icing of the tracks caused by creeks overflowing during the winter has also to be taken care of and continually watched especially during the extreme cold periods.
There are many other additional railroad hazards of winter origin that prevent the speedy and safe operation of trains in Alaska in comparison to most railroads in Continental United States. During the spring breakup cake ice starts floating down the rivers blocking and jamming the entire channels causing the ice to be deposited on the adjacent tracks. The section of mainline along the Susitna River between MP 225.0 and 263.0 are subject to these ice jams. Mud slides from thawing slopes of glacial moraine are also associated with the spring breakup. Rocks and clay loosened by the winter frost fall or slide onto the tracks and cause many train delays. Two large locomotive-type ditchers are constantly employed cleaning away such rock falls and slides.
Excessive snowfall at Whittier where the total winter snowfall sometimes measures over 40 feet is another difficulty that the maintenance crews have to deal with. As a constant wind is generally blowing at this location, causing no end of snow removal from the yards and main liner, the job of keeping this trackage operable is not an easy one.
As it would be a very complicated and almost impossible accounting problem to accurately define and allocate winter track maintenance and train operation costs from summer maintenance, improvement and operation charges, no attempt has been made by The Alaska Railroad to make such detailed segregations, except on major activities such as snow and ice removal, shimming and such like definite work, but there are so many minor yet expensive maintenance and operating charges that overlap and extend into both periods of operations that it would be misleading to quote the ratio of costs between these periods of operation.
The extensive rehabilitation program completed in 1953, comprising the laying of new 115 lb. rail replacing worn out 70 lb. rail on new treated ties on a well-ballasted and widened road bed, plus the construction of better drainage facilities and the replacement of old wood bridges with new steel structures, has greatly increased the efficiency of operation and should reduce the annual maintenance cost of this Railroad.