About 6:06 p.m., on November 9, 1977, 2 SD-45 locomotive units and 35 cars of Louisville & Nashville freight train No. 407 derailed when entering a 6°04' curve at Pensacola, Florida. The adjacent tank heads of the 18th and 19th cars were punctured during the derailment by a loose wheel and axle assembly; this released anhydrous ammonia into the atmosphere. Two persons died and 46 were injured as a result of the derailment, release of anhydrous ammonia, and evacuation of about 1,000 persons. Property damage was estimated to be $724,000.

The National Transportation Safety Board determines that the probable cause of this accident was the overturning of the high rail in the 6°04' curve which caused track gage to widen. The high rail tipped because it was not able to withstand the lateral forces generated by the 6-axle locomotive units because of the tight gage of the track, and the forces generated because of the placement of a lightly loaded long car and an empty short car directly behind the locomotive with large trailing tonnage. The cause of the fatalities and injuries was the release of anhydrous ammonia through punctures in the tank cars; head shields would have prevented such punctures.

INVESTIGATION

The Accident

About 5:31 p.m., on November 9, 1977, Louisville & Nashville Railroad Company (L&N) freight train No. 407 departed Goulding Yard, Pensacola, Florida, southbound for Chattahoochee, Florida. The train consisted of 3 SD-45 locomotive units and 127 cars, including 16 tank cars carrying anhydrous ammonia. A predeparture inspection and airbrake test at Goulding Yard disclosed no defects. The train had originated in New Orleans, Louisiana, earlier in the day.

When the train was 9.5 miles south of Goulding Yard and moving at 35 mph, it entered a 6°04' curve at Gull Point, Pensacola. The engineer did not observe any defects in the track or any drainage problems as the

locomotive entered and moved through the curve. However, the brakeman and reserve engineer sitting on the left side of the locomotive cab looked to the rear to visually inspect the train and saw sparks coming from under the rear locomotive units and the following seven cars just as the locomotive reached a road crossing beyond the middle of the curve. They could not see the remaining portion of the train because of a wooded area along the curve. The rear truck of the second locomotive

unit, the third unit, and the following 35 cars derailed.

The engineer stated that he felt an unexpected emergency braking and reached for the brake valve, but the brakes were already in the emergency mode as a result of the derailment. The throttle was in the

second power position and the ammeter was registering about 100 amperes before the derailment. However, the engineer stated that he had reduced the throttle in greater than 10-second intervals from the eighth to the second position during the 1.4 miles before entering the curve. This reduced the speed of the train from 40 mph to the required 35 mph through the curve. The brakes had not been applied on the train or locomotive since leaving Goulding Yard. The three crewmembers in the locomotive stated they did not hear or feel any unusual motions in the locomotive before the derailment.

The locomotive and cars traveled 800 feet before stopping after the emergency brake application. The conductor and flagman, who were in the caboose at the rear of the train, stated that as the train stopped they noted no slack, jerking, or buff forces in the caboose. The conductor called the engineer on the radio when the train stopped at 6:06 p.m. and was told that the train had derailed. The first two cars, a long flat car loaded with one truck trailer and an empty covered hopper car, remained upright and coupled to the locomotive. The next 11 cars were tipped but remained in line along the following 900 feet of track. 14th through 35th cars jack-knifed and piled up within the next 700 feet. (See figure 1.)

The

The conductor inspected the 92 remaining cars and found no defects or derailments. The head brakeman and reserve engineer, who were inspecting the derailed portion of the train, detected the smell of ammonia and noticed a vapor cloud developing when they arrived at the 10th car; they informed the engineer by radio. The engineer radioed the Goulding yardmaster that the train was derailed and that ammonia was leaking. The lead locomotive unit was uncoupled and moved about 1/2 mile east to escape the enlarging vapor cloud. None of the crewmembers were injured in the accident.

The track roadbed follows the western shoreline of Escambia Bay in the accident area and is adjacent to Pensacola's eastern residential area. The water-level route has minimal gradients and its curvature conforms to the shoreline. At Gull Point the track curves inland through a wooded area and separates six beachside homes from the homes fronting

on Scenic Highway just west of the track. An extension of Creighton Road provides access to the Gull Point homes and crosses the track near the center of the curve. The ammonia vapor cloud enveloped the area. Two persons died from ammonia inhalation and 46 others were injured.

Sixteen of the 17 derailed tank cars contained anhydrous ammonia and were located between the 7th and the 28th cars. The 17th tank car contained solvent and was leaking slightly at a valve. The other derailed cars contained commodities such as feed, lumber, and automobiles. Twelve of the 35 derailed cars were destroyed and the others were heavily damaged. The 18th car was punctured on the right side near the junction of the head and shell of the tank. The puncture consisted of three parallel, 1/4-inch-wide, vertical cracks, about 6 inches apart, and located near the 4-o'clock position from the top of the tank. One 19inch-long crack was adjacent to the weld of the head and shell. The other two cracks were 19 inches and 9 inches long respectively. The puncture of the 19th car was a 3-inch-wide by 38-inch-long tear in the leading tank head. It was located near the 10 o'clock position from the top and about 31 inches to the left of the vertical centerline. (See figure 2.)

The high rail throughout the curve was initially tipped outward within its tie plates. The low rail was initially tipped inward on its tie plates from 200 feet into the curve up to the point where the locomotive stopped. The total track structure in the first 800 feet of the curve was destroyed by the derailed cars. About 1,000 feet of the remaining

track in the curve was damaged.

All trees and ground vegetation east of Scenic Highway and within 1,000 feet of the punctured tank cars were discolored and leaves withered by the ammonia vapor cloud. Birds and small wildlife were found dead within the 1,000-foot area.

Creighton Road access to the Gull Point area east of the accident site was blocked by the derailed cars. A water main crossing under the track, which provided service to the easterly Gull Point residents, was broken in the derailment.

1/ One person died 2 months after the accident as a result of her injuries.