Derailment at Yarnell. Mont., 1955

You can't visit the site of this derailment today — unless you are wearing scuba gear. Yarnell, MT is now at the bottom of Lake Koocanusa, as is the former GN main line, which was flooded by the construction of the Libby dam in 1967. The present-day main line was re-routed through the new, 8-mle long Flathead tunnel.

Th is accident was caused by a rock dislodging from an adjacent cliff as the Western Star sped by at 52 m.p.h., rolling under the 12th car and causing the truck of the 12th car to derail.



Report No. 3635


Report No. 3635





Great Northern
June 20, 1955
Yarnell, Mont.
Kind of accident
Train involved
Train number
Engine number
Diesel-electric unite 358A, 358B, and 358C
13 cars  
Estimated speeds
52 m. p. h.  
Timetable, train orders, and automatic block-signal system
Single; 3 degrees 26'curve; 0.28 percent descending grade westward
5:02 p.m.
10 injured
Rock falling upon track under train



July 26, 1955

Accident near Yarnell, Mont., on June 20, 1955, caused by a rock railing upon track under a train.


CLARKE, Commissioner:

On June 20, 1955, there was a derailment of a passenger train on the Great Northern Railway near Yarnell, Mont., which resulted in the injury of nine passengers and one train-service employee.

Report No. 3635 Great Northern Railway Near Yarnell, Mont. June 20, 1955

Location of accident and method of operation

mapThis accident occurred on that part of the Kalispell Division extending between Whitefish and Troy, Mont., 134.48 miles. In the vicinity of the point of accident this is a single-track line, over which trains are operated by timetable, train orders, and an automatic block-signal system. The accident occurred on the main track at a point 99.39 miles west of whitefish and 3.42 miles west of Yarnell. From the east there are, in succession, a 3 degrees 05'curve to the right 1,567 feet in length, a tangent 1,621 feet, and a 3 degrees 26'curve to the left 216 feet to the point of accident and 370 feet westward. The grade for west-bound trains is 0.28 percent descending at the point of accident.

The track structure consists of 112-pound rail 39 feet in length, laid new in 1940 on an average of 24 treated ties, to the rail length. It is fully tieplated with double-shoulder tie plates, spiked with two rail-holding spikes per tie plate and one plate-holding spike per tie plate on curves, and is provided with 4-hole 26-inch joint bars and an average of 32 rail anchors per rail. It is ballasted with processed gravel to a depth of 8 inches below the bottoms of the ties.

In the vicinity of the point of accident the railroad parallels the Kootenal River on the south, and the track is laid on the adjacent hillside. The accident occurred approximately 350 feet west at the east end of a side-hill rock cut. Immediately west of the point of occident the track enters a through rock cut about 540 feet in length. At the point of accident the toe of the south wall of the cut is 10 feet from the center-line of the track, and at a point 15.4 feet above the level of the track the wall is 20.4 feet south of the center-line of the track. On the north side the ground line is practically at the grade of the track. The rock in the cut in which the accident occurred is quartzite.

Automatic signal 1317.3, governing west-bound movements, is located 1.32 miles east of the point of accident.

The maximum authorized speed for passenger trains in the vicinity of the point of accident is 79 idles per hour, but it is restricted to 55 miles per hour on the curve on which the accident occurred.

Description of accident

No. 3 a west-bound first-class passenger train, consisted of Diesel-electric unite 358A, 358B, and 358C, coupled in multiple-unit control, one mail car, one baggage car, four coaches, one lunch-dormitory car, one dining car, four sleeping care, and one lounge-sleeping car, in the order named. The second car was of conventional all-steel construction. The other cars were of lightweight steel construction and were equipped with tightlock couplers. This train departed from Whitefish at 3:14 p.m., 24 minutes late, passed Valcour, 11.24 miles east of the point of accident and the last open office, at 4:51 p.m. 16 minutes late, passed signal 1317.3, which indicated Proceed, and while moving at a speed of 52 miles per hour the twelfth and thirteenth care were derailed at a point 3.42 miles west or Yarnell.

There were no separations between the units of the train. The train stopped with the rear end of the thirteenth car 824 feet west of the point of derailment. The twelfth and thirteenth oars were derailed to the north and stopped approximately in line with the track. The twelfth car leaned to the north at an angle of about 35 degrees, and the thirteenth car leaned to the north at an angle of about 15 degrees. Both care were. somewhat damaged.

The conductor was injured.

The weather was clear at the time of the accident, which occurred at 5:02 p.m.


As No. 3 was approaching the point where the accident occurred the speed was 52 miles per hour, as indicated by the tape of the speed-recording device. The enginemen were maintaining a lookout ahead from the control compartment at the front of the locomotive. The members of the train crew were in various locations in the cars of the train. The locomotive and the cars were riding smoothly, and the enginemen said they observed no obstruction on the track. The members of the crew first became aware that something was wrong when the derailment occurred and the brakes became applied in emergency as a result of a broken brake pipe.

Examination of the equipment and the track after the accident occurred disclosed that a spring plank safety hanger on the front truck of the twelfth car had struck a rock which had become dislodged from the south wall of the cut and fallen to the track. This rock, which measured 10 inches by 14 inches by 18 inches and weighed 163 pounds, was found on the north side of the track. It bore marks of a fresh fracture and traces of paint similar in color to the paint on the spring plank safety hanger. Marks on the wall of the cut indicated that this rock had become dislodged from the top of a flat rock at the top of the wall. The spring plank safety hanger on the north aide of the front truck of the twelfth car bore indications of having struck a rock and was bent upward and backward approximately 4 inches. Normally this safety hanger is 8 inches above the level, of the tops of the rails. No defective condition of the equipment was found which appeared to have existed prior to the time of the derailment. The first mark of derailment on the track structure was a flange mark 10 inches inside the south rail opposite the point at which the rock was found. Apparently, as No. 3 was passing through the out the rock became dislodged and rolled upon the track in front of the twelfth car, and when the safety hanger struck the rock the side of the truck was raised sufficiently to permit the flanges of the wheels to cross the rail.

The section foreman had been working in the immediate vicinity of the point of accident on the day on which the accident occurred, and the roadmaster had made a trip over this territory 6 days prior to the day of the accident. These employees observed no unusual condition. They said that in the past they had experienced no difficulty with falling rocks at the point at which the accident occurred.


This accident was caused by a rock falling upon track under a trains.

Dated at Washington, D. C., this twenty-sixth day of July, 1955.

By the Commission, Commissioner Clarke.



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