DEPARTMENT OF LABOR
MINE SAFETY AND HEALTH ADMINISTRATION
Metal and Nonmetal Mine Safety and Health
Accident Investigation Report
Surface Nonmetal Mine
Fatal Powered Haulage Accident
Limerock Industries, Incorporated
Ocala, Marion County, Florida
Mine I.D. No. 08-01078
November 5, 1996
Terry E. Phillips
Supervisory Special Investigator
Steve J. Kirkland
Mine Safety and Health Inspector
Mine Safety and Health Administration
135 Gemini Circle, Suite 212
Birmingham, Alabama 35209
Alfred Lee Oats, serviceman/truck driver, age 45, drowned at approximately 5:10 p.m. on November 5, 1996, when the haulage truck he was driving traversed a curve and continued in the same arc as the curve without straightening. The truck left the roadway and went into a water-filled pit. The victim had a total of nine months mining experience, all at this mine. Oats had received some general task training prior to operating the haulage truck, however, he had not received any other training required by 30 CFR, Part 48.
Gene Pollock, safety manager of Limerock Industries, Incorporated, notified the MSHA Bartow, Florida, Field Office of the accident at 7:35 a.m., November 6, 1996. The accident investigation was started the same day.
Clifton Pit, an open pit crushed limestone operation, owned and operated by Limerock Industries, Incorporated, was located off Northwest 27th Avenue and Northwest 42nd Road in Ocala, Marion County, Florida. The principal operating official was Luther Maxwell White, Sr., president. The mine was normally operated one, 10 to 12-hour shift per day, 5 days per week. Ten persons were employed.
Overburden was removed and then limestone was mined in two stages. The first stage was accomplished by using dozers with rippers to loosen the material. The loosened limestone was then pushed into a pile where it was fed into a portable crusher with a trackhoe, crushed to size, and stockpiled. The first stage removed limestone to a depth just above the water table. The second stage consisted of drilling and blasting limestone 50 feet below the water table. The broken material was removed from underwater by dragline, stockpiled to allow it to dry naturally, and was later crushed and stockpiled. The product was primarily used for road base material on White Construction Company's highway construction jobs.
The last regular inspection at this operation was conducted on June 4, 1996. Another regular inspection was conducted in conjunction with this investigation.
PHYSICAL FACTORS INVOLVED
The accident occurred on the roadway that went from the dump site to the pit where waste material was being extracted and then hauled by truck out of the pit. After unloading material at the dump site, the driver would go approximately 300 feet on level roadway. The road then curved at approximately a 90 degree turn down a 10 percent grade for a distance of 675 feet before leveling out at the pit working area. The road then continued for another 435 feet to where the truck was loaded with waste material. The surface of the road bed consisted of a layer of hard-packed material that was a mixture of crushed rock and a clay-like matrix which became very slick when wet. The roadway was reportedly wet and slick on the day of the accident from water draining out of the bed of the truck from the wet material being transported. There was no berm where the truck left the roadway and 42 feet to the right of the roadway was a water-filled pit, approximately 200 feet in diameter and 30 feet deep.
Two skid marks that were the width of a single tire on the truck involved in the accident were observed along the declined roadway. They were both about 13 feet in length and apparently were made by the left front tire of the truck. The first skid was up high on the decline, approximately 150 feet down from the top and the second one was about 580 feet from the top or approximately 3/4 of the way down.
The truck involved in the accident was a 1976 Terex, 40 ton capacity haulage truck, Model 33-07 Hauler, serial number 64798. The truck was powered by a turbo charged, V-12 Detroit diesel engine and had an Allison CLBT 5960, 6-speed torqmatic transmission, independent hydrostatic powered steering, and air actuated brakes on the four wheels.
The primary braking system on the Terex truck was an air operated, internal expanding, drum/shoe system. The park and emergency brake was an integral part of the service brake system designed to provide a reserve of air upon loss of power to bring the vehicle to a safe stop with normal use of the foot pedal and could be activated by manually positioning the lever of an instrument panel air valve. This instrument panel air valve control lever had three positions: release, emergency, and park. The release setting was the normal operating position as this released the application of the brakes on all four wheels. The emergency and park positions applied the brakes to all four wheels and in either of these positions, the brakes would be locked on until the lever was placed in the release position. Spring-loaded safety chambers on the slack adjusters activated the brakes automatically on all four wheels if the air pressure dropped below 45 psi.
The gear selector inside the cab of the truck was mounted on the floor to the right of the driver seat in a typical console with the gear designations labeled and clearly visible alongside the shift lever. The respective gear selection positions for the gear selector lever were normally clearly defined, from sixth gear at the top to reverse gear at the bottom, by notches (or protruding flanges) that alternated from side to side along the sides of the selector lever slot. The protruding flanges that created the notch effect and provided the stops between each gear on this truck had been cut off except for the one that separated neutral from reverse. This would allow the driver to "zip" through the entire range of gears from sixth to reverse in one quick motion if the shift lever was kept against the left side of the selector lever slot.
The gear selector lever in the console inside the cab was connected to the transmission by linkage and a control cable inside its outer shielding. The control cable outer shielding was normally fastened in a slot in a bracket mounted on top of the transmission housing and the control cable continued on from there to the gear control plunger on the side of the transmission.
The steering system on this Terex truck contained a nitrogen charged accumulator which provided for a limited amount of emergency steering of approximately two turns, lock to lock.
Divers who searched for the victim found the truck fully submerged, lying on its right side in 30 feet of water with the back-up alarm beeping. The driver-side door was unlatched and the victim was found approximately 90 feet to the front and left of the truck.
An examination of the truck after the accident found the instrument panel emergency/park brake control lever in the release position, the air pressure at zero, and the brakes set on all four wheels as they should have been. The brake slack adjusters were examined and determined to be adjusted within the recommended range on all four of the wheels. The brake system was pressurized with an external source of air pressure and the brakes appeared to function properly on all four wheels when activated by the foot pedal and the manually operated lever on the instrument panel. The external air supply was used to fully pressurize the system again and then was disconnected from the system. The brakes were applied six times and were held each time for a few seconds before the air pressure in the system dropped to just below 60 psi.
The gear selector lever inside the cab indicated the transmission was in fourth gear, but the transmission was actually in reverse. This explained why the divers could hear the backup alarm beeping on the submerged truck when they entered the water to search for the victim. Close examination of the gear selection assembly revealed that the control cable was not secured to the bracket; the area of the cable containing the securing nuts had moved beyond the mounting bracket toward the transmission and the cable was lying in the bottom of the mounting bracket slot. While the control cable was still in the unsecured condition, the gear selector lever on the console was moved to various selections and the transmission remained in the reverse position. The control cable was secured in its normal position and the selector settings inside the cab coincided with the proper positions on the transmission from reverse through sixth gear.
Employees at the operation who had previously operated the truck said the gear selector lever would change gears in and out of reverse and seemed to work properly except it would only go up to fourth gear. This condition was duplicated when the control cable was loosened from the mounting bracket and lifted out of the slot but the retaining nuts were allowed to catch or wedge against the side of the bracket. The control cable was then freed from being caught on the mounting bracket and moved back into the position it was in when the truck was removed from the water. The transmission would then go into reverse when the console gear selector was placed in first gear and would not come out of reverse when moved all the way to the fourth gear position. This was a duplication of the condition that was found when the truck was first examined after it was removed from the water.
The truck was started and the air pressure rose to the normal operating pressure from the internal air compressor and the brakes again appeared to function properly. The truck was then driven a short distance to test the brake and steering systems and both appeared to function properly. Both the brake and steering systems continued to operate on their reserve capacity after the engine was shut off. The steering wheel could not be turned when the engine was not running except for the limited amount provided by the accumulator reserve.
There were no established procedures in place that would ensure that all mobile equipment was inspected for safety defects by the equipment operator before being placed in operation each shift.
Weather conditions on the day of the accident were clear and warm.
DESCRIPTION OF ACCIDENT
Albert Lee Oats (victim) reported for work at his normal starting time of 7:00 a.m. on November 5, 1996. He performed his routine duties of servicing the equipment at the mine until approximately 1:30 p.m. when he was assigned to operate the Terex haulage truck, also his normal duty. He and Douglas Standridge, equipment operator, were instructed to remove the waste material in the pit. At approximately 4:45 p.m., Standridge loaded the haulage truck operated by Oats, and Oats went to the dump site to unload the material before returning for another load. The round trip took approximately 5-10 minutes. After Oats left with the load, Jack Hudson, superintendent, stopped by and was having a discussion with Standridge when Gerald Martin, equipment operator, drove down the 10 percent decline to where they were talking and asked them where Oats was. They told him that Oats was up dumping a load of material but he was overdue to be back. Martin replied that he did not see Oats at the dump area when he had just came by there on his way down. Martin said he also noticed two separate skid marks up on the declined roadway.
A search for Oats began and they found fresh tracks that left the right side of the roadway at the end of the curve and continued to the edge of the water. They saw a hard hat and glove floating on the water. Hudson called for emergency 911 while Martin took his clothes off, entered the water and dove down trying to locate the truck but was unsuccessful.
The Marion County Rescue Squad, with divers, arrived at approximately 6:00 p.m. and began diving in search of Oats but were unsuccessful in locating him before nightfall and the search was discontinued at 9:30 p.m. The search was resumed the next morning and the victim was found at 9:15 a.m. approximately 90 feet from the truck. The body was recovered and the Medical Examiner pronounced the victim dead at the scene. The autopsy results indicated that the cause of death was due to drowning.
There were no witnesses to the accident, however, evidence and information obtained during the investigation indicate the following most likely occurred: The retaining nuts that secured the gear selector control cable in the mounting bracket became loose. The control cable worked out of its position in the slot of the mounting bracket, however it somehow remained in a position that allowed the gear selector to work, except that it would go only as high as fourth gear. Possibly after the victim dumped the last load, the control cable moved into the position in which it was found after the accident. This position of the control cable allowed the transmission to go into reverse when the victim shifted to what he thought was first gear as he started down the decline. The engine probably stalled if the transmission went into reverse while going forward down the decline. The truck continued to roll downhill and the emergency steering provided by the reserve in the accumulator allowed the truck to be steered through a portion of the curve before it was depleted and the steering system failed to operate. Oats was unable to straighten the wheels coming out of the curve and the truck went off the right side of the road, traveling 42 feet into the water-filled pit.
It could not be determined why the victim was unable to stop the truck by using the brakes; however, the wet roadway may have been too slick for the truck to stop when the brakes were applied.
The equipment defect created by the gear selector control cable being outside its mounting bracket was the primary cause of the accident. Failure to establish procedures to check for and record equipment defects on mobile equipment also contributed to the accident. Failure to have a berm along the edge of the roadway contributed to the severity of the accident.
Order No. 4087741
Issued on November 8, 1996, under provisions of Section 103(k) of the Mine Act:
Order Number 4087742
Issued on December 5, 1996, under the provisions of Section 104(d)(1) of the Mine Act for violation of 30 CFR 56.9300(a).
Citation Number 4087744
Issued December 5, 1996, under the provisions of Section 104(a) of the Mine Act for violation of 30 CFR 50.10:
Order Number 4087745
Issued January 23, 1997, under provisions of Section 104(d)(1) of the Mine Act for violation of 30 CFR 56.14100(a):
Order Number 4087746
Issued on January 23, 1997, under provisions of Section 104(d)(1) of the Mine Act for violation of 30 CFR 56.14100(b):
/s/ Terry E. Phillips
Supervisory Special Investigator
/s/ Steve Kirkland
Mine Safety and Health Inspector
Approved by: Martin Rosta, District Manager
Related Fatal Alert Bulletin: