1975_美国_HAR7503.pdf

8 PB241989

SS-H-32

HIGHWAY ACCIDENT REPORT

GEORGE WOLLMAN MEATS, INC., TRUCK/AUTO/GREYHOUND BUS COLLISION AND FIRE, NEW JERSEY TURNPIKE, BORDENTOWN, NEW JERSEY OCTOBER 19,1973

ADOPTED: MARCH 12, 1975

NATIONAL TRANSPORTATION SAFETY ROARD

Washington, D. C. 20594

REPORT NUMBER: NTSB-HAR-75-3

TECHNICAL REPORT DOCUMENTATION PAGE

FOREWORD

The accident described in this report has been designated a major accident by the National Transportation Safety Board under the criteria established in the Safety Board's regulations.

The report is based on facts obtained from an investigation by the Safety Board. Information was also provided by the Bureau of Motor Carrier Safety of the Federal Highway Administration, Civil Aeromedical Institute of the Federal Aviation Administration, the National Highway Traffic Safety Administration, and the New Jersey State Police.

The conclusions, the determination of probable cause, and the recommendations herein are those of the Safety Board.

TABLE OF CONTENTS

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NATIONAL TRANSPORTATION SAFETY BOARD WASHINGTON, D. C. 20594

HIGWAY ACCIDENT REPORT

Adopted: March 12, 1975

GEORGE WOLLMAN MEATS, INC., TRUCK/AUTO/BUS COLLISION AND FIRE, NEW JERSEY TURNPIKE, BORDENTOWN, NEW JERSEY OCTOBER 19, 1973

SYNOPSIS

At 8 p.m. on October 19, 1973, a tractor-semitrailer was traveling south in the right lane of the southbound portion of the New Jersey Turnpike at about 55 mph. A Greyhound bus was traveling north in the right lane of the northbound portion of the Turnpike. A private autowas traveling in the center lane of the northbound portion and was passing the bus.

The left front tire of the truck blew out; the tractor veered to the left and crashed through the median guardrail into the northbound lanes. The truck struck the automobile and crushed it between the truck and the bus; the automobile split in half, and the rear half caught fire. The truck ran off the northbound lanes, through a guardrail, down a 50-foot embankment, and turned onto its right side. The truckdriver was ejected; he was not wearing an available seatbelt.

The automobile driver, the automobile passenger, the busdriver, and six bus passengers died in the crash. The truckdriver and 10 bus passengers were injured. Property damage amounted to $100,000.

The National Transportation Safety Board determines that the probable cause of the accident was the sudden deflation of the left front tire on the tractor which caused the driver to lose control of the vehicle. The sudden deflation resulted from a gross failure of the tire sidewall due to under inflation caused by an undetected nail puncture.

Contributing to the fatalities and injuries was the inadequacy of the median guardrail to prevent the tractor-semitrailer from entering into the opposing lanes of traffic.

FACTS

The Accident

At 8 p.m. on October 19, 1973, a truck was traveling in the right lane of the southbound portion of the New Jersey Turnpike at 55 mph. (See Figure 1.) A Greyhound bus was traveling in the right lane of the north-bound portion of the Turnpike. A 1972 Ford Mustang sedan was traveling

〔图〕BRIDGE16' CONCRETE MEDIAN=112' LEFT FRONT TRACTOR TIRE MARKS10' SHOULDER5' SHOULDERBRIDGE GUARORAILLANELANELANE12°1212MO

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in the center lane of the northbound portion of the Turnpike, and was passing the bus. The driver of the truck stated that he had no steering control problems with the truck until after he heard a sudden loud noise, which sounded like a gunshot. He said, "The left front seemed to drop, and I couldn't keep the unit from going to the left;" he said that he did brake, "a little," but that the unit went "sharp left" into the guard-rail and that, "it happened very quickly." The truck struck the curbing of the concrete median located on a bridge-over structure. At that point, the driver was dislodged from behind the steering wheel but remained in the cab. The truck then struck and crashed through the median guardrail which was located on the grass median and traveled into the northbound lanes where it struck the automobile. (See Figures 2 and 3.)

〔图〕DBAA\n

Figure 2. Approach of truck toward guardrail. Note: A - tire marks on concrete median. A - tire mark on pavement. B - tracking of vehicle across grass median. C - 56 feet of guardrail damage. D - truck penetration of shoulder guardrail.

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〔图〕口\n

Figure 3. Wavy tire marks leading up to concrete median.

The automobile was spun clockwise and into the left front of the bus, where it was crushed between the truck and the bus. The automobile split in half, and the rear half caught fire. The front half traveled 14 feet east of the impact point and caught on the guardrail of the right north-bound shoulder. The bus and rear half of the automobile traveled 30 feet north in the right lane and stopped.

The truck continued across the northbound lanes, ran off the east shoulder, proceeded over the front half of the automobile, crashed through the guardrail, plunged down the 50-foot embankment during which the driver was ejected, and stopped at the bottom where it overturned onto its right side.

Accident Site

The accident occurred on the New Jersey Turnpike near Bordentown, New Jersey, at milepost 57+18 delineators. Delineators are 150 feet apart. In that area, the New Jersey Turnpike consists of six 12-foot lanes, three northbound and three southbound. The north and southbound

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lanes are separated by a 16-foot grass median. Two W-section guardrails are located in the median--one for each direction of travel. On the outer edges on each side of the road, a 10-foot gravel shoulder is bounded by a W-section guardrail. On the right side of the northbound lanes the guardrail protects against a 50-foot embankment.

A concrete bridge is located north of the point at which the truck impacted the median barrier, automobile, and bus. A 16-foot-wide concrete median is located down the center of the bridge. The double W-section guardrail continues down the center of the median.

The truck impacted the median barrier 25 feet south of the bridge. Fifty-six feet of barrier in the grass median was damaged. Twenty feet of guardrail on the northbound shoulder was crushed to the ground by the front of the automobile and by the truck.

Environmental Factors

The road was dry, the weather was fair, and traffic was medium to heavy. The accident occurred in a rural area; it was dark, and there was no artificial lighting. The road was level, in good repair, and had a posted speed limit of 60 mph.

Marks on the Roadway and Median

A wavy tire mark started at the center of the middle southbound lane and continued 112 feet to the point at which the truck struck the concrete bridge median. Another 6 feet of tire marks were visible on the curbing. A second tire mark, which ran parallel to the wavy mark, began at the east (left) edge of the southbound lane and continued 15 feet to the right edge of the grassy median. (See Figure 3.) These tire tracks continued through the grassy median at a 19° angle for 25 feet to the point of impact with the median barrier. From the barrier, 97 feet of tire tracks and tire marks were visible in the median and in the north-bound lanes to the point at which the truck struck the automobile. The point at which the truck struck the automobile and the bus was identified by gouge marks in the road surface and dirt, debris, and rust-colored water in the center lane of the northbound portion. The bus and automobile involved in the accident did not leave tire marks on the highway before impact with the truck.

The Truck

The tractor-semitrailer was leased by George Wollman, Inc., from Hubler Rentals, Inc., of Allentown, Pennsylvania. The 1970 Mack tractor had a cab-over-engine and front wheel brakes and was diesel-powered. It had three axles and manual steering, and was equipped with seatbelts.

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The deflated left front tire was a "Super Traction Safety Rib" made for Super Tire Engineering Co., of Camden, New Jersey, by a manufacturer in Israel. The tire size was 10:00-20; it was made of Nylon and had a 12-ply rating. The tire load rating was 5,780 lbs. at 85 lbs/in $^{2}$ cold inflation pressure, and the gross axle weight rating was 11,560 lbs. The tire tread design was five rib, and tread depth exceeded requirements.

The truck operator's maintenance records indicated that on April 15, 1973, two new front tires were installed on the tractor. At that time, the odometer on the tractor read 97,922 miles. On July 6, 1973, the left front tire on the tractor was replaced at 108,231 miles. Maintenance personnel could not recall the reason for the replacement.

The 1970 Trailmobile trailer was equipped with a refrigeration unit, tandem axles, dual wheels, and air brakes. It was carrying 35,797 lbs. of meat which was loaded from the floor to 3 feet above the floor. The tread depth of the trailer tires was greater than the minimums required by regulations.

Witnesses

A witness, who was following 100 yards behind the truck, stated that his vehicle and the truck were traveling about 60 mph. He further stated that suddenly, the truck swerved sharply to the left, went through the guardrail, and collided with the bus. After the collision a fire began.

One motorist stated that she was traveling in the left lane ahead of the Mustang and just ahead of the bus, when she saw truck headlights coming toward her from the southbound lanes. She accelerated her car to get out of the path of the truck. She then heard a noise and felt a jolt. She stopped her car and found that the metal, demountable flange from the left front wheel of the truck had lodged in the left front fender of her car.

A second motorist was following the Mustang in the left lane and about 33 feet behind the bus. He stated that he saw the truck come through the median guardrail, hit the rear of the Mustang, crash into the side of the Mustang in the center lane, and crush it into the front of the bus.

Vehicle Damage

Automobile—The automobile was cut in half and crushed. The pile of twisted metal no longer resembled an automobile. The rear half of the vehicle was burned. (See Figures 4 and 5.)

Truck--The tractor was ripped from the chassis and destroyed; therefore, only the undercarriage and tires could be examined. (See Figure 6.) The tractor was burned, and the brakeshoe on the left front drive axle was broken.

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〔图〕插图

Figure 4. Front half of Mustang.

〔图〕插图

Figure 5. Rear half of Mustang.

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〔图〕插图

Figure 6. Damaged tractor.

The left front tire was deflated and burned on the inside sidewall. The outside sidewall was unburned and contained a jagged, 14-inch opening. (See Figure 7.) This opening was located between the bead and the tread and followed the circumference of the tire.

The mean tread groove was 15/32 of an inch. 1/ The inside sidewall was burned and cut in two places. One cut at the bead side flange area had not penetrated through the ply. The second cut was large and extended 3 inches on the tread face and 2 inches down the shoulder. The cords in the sidewall of the tire were broken for almost the full circumference of the inside of the tire.

Over a 6-month period following the accident, the tire was examined by several investigators and tire experts. During an examination on April 24, 1974, the head of a nail was found protruding from a groove in the tire tread. The head of the nail was discolored and difficult to detect. It was located at the bottom of the second groove from the outside of the tire and 40 inches forward of the 14-inch tear in the outside tirewall.

1/ "49 CFR 393.75 Tires: (b) Any tire on the front wheels of a bus, truck, or truck tractor shall have a tread groove pattern depth of at least 4/32 of an inch when measured at any point on a major tread groove. Measurements shall not be made where tie bars, humps, or fillets are located."

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〔图〕插图

Figure 7. l4-inch tear in outside wall of left front truck tire.

The point of the nail did not protrude through the inside of the casing. It could not be felt by a person rubbing the interior of the casing with his fingers. (See Figure 8.)

After the accident, the inner tube was missing from the tire and was not recovered. However, the inner tube must have been present before the accident, because the tire could not have supported the load without it.

The flap was in good condition and had not been wrinkled or pinched. The flap splice was smooth and the edges were round and would not have damaged or cut the inner tube. The fabric which surrounded the valve hole was abraded.

The inside sidewall and tread face of the right front tire was burned. The tread was about 6/32 inch deep in the groove near the center of the tread pattern. Except for the left front tire, the other tractor tires were inflated and appeared to be in good condition.

The front of the trailer was damaged heavily. (See Figure 9.) The front of the unit was torn open. The body was torn from the frame, and the frame was sprung. The spring assemblies were broken and separated from the chassis. Except for the inner, left rear tire, the tires were inflated. The inner, left rear tire, was deflated, but there was no visible damage.

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〔图〕插图

Figure 8. Head of nail embedded in the left front tire of the truck.

〔图〕插图

Figure 9. Damaged right front end of the trailer.

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Bus--The front of the bus was torn open, and the driver's seat and compartment were destroyed (See Figure 10.) The sidewall of the right-front tire was cut, and rubber was missing. The tire was flat.

〔图〕GREYHOUND\n

Figure 10. Damaged front end of bus.

Of the 43 seats in the bus, 33 seats remained in place and were secured firmly. Broken back rests were found on two seats, one on each side near the rear of the bus. The 10 missing seats were located at the front of the bus where the bus had been penetrated. The next to last window in the rear of the bus, on the right side, was cracked in several places.

Rescue Activities

Rescue squads responded promptly from Allentown, Bordentown, Hightstown, Florence, and Roebling, and there was no delay in medical services to the injured.

Injuries to Persons

In the Automobile--The driver of the automobile and his passenger were killed.

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In the Bus--The busdriver and five passengers were killed in the accident. The remaining 11 passengers were hospitalized; 3 were in serious condition. One of the three died 5 days after the accident.

In the Truck--The truckdriver, who was not wearing the available seatbelt, 2/ was ejected from the truck as it plunged down the embankment. He received lacerations on his left leg, and bruises and abrasions to his head. He was treated at a nearby hospital and released.

Other Information

Background of the Truckdriver--The 21-year-old truckdriver held a valid New Jersey driver's license. On July 22, 1973, he had been examined and found physically qualified to operate motor vehicles in interstate commerce. New Jersey Motor Vehicle Department records reveal no traffic violation convictions or previous traffic accidents. While in the U.S. Army, he was a truckdriver for 2 years. After being discharged from the Army, he completed a 3-week driver training course for commercial vehicles at Ryder School. The school teaches the following with respect to blowouts:

"Keep a firm and stead grip on the steering wheel--don't oversteer to correct the swerve or pull. If a front tire goes, there will be a strong pull toward the side with a blowout. A rear blowout tends to cause weaving of the rearend.

Above all, don't slam on brakes! Brake smoothly..."

The truckdriver stated that before starting the trip, he made a visual inspection of the tires and other equipment and found no defects.3/

Front Tire Failure Statistics--Bureau of Motor Carrier Safety (BMCS) report 4/ states, "Consistently, we have found that the second leading cause (after brake failures) of mechanical defect accidents is tire failures. And consistently, over 60 percent (almost 2/3) of these accidents are caused by front tire failures: These front tire failures (775 out of 1,186), reported in the period 1968-1970, resulted in 25 fatalities, 409 injuries, and 4.8 million dollars in property damage." (See Appendix A.)

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Another BMCS report 5/ states that, in 1971, accidents involving front tire failures were responsible for 10 fatalities, 155 injuries, and $2.1 million in property damage. These data do not include private carriers who were exempt from BMCS requirements until January 1, 1973.

ANALYSIS

Left Front Tire Failure

Load Condition--In a proposed rulemaking $\underline{6}/$ the BMCS states that two of the main causes of tire failure are operating while tires are either overloaded or underinflated. The truckdriver said that during his pretrip inspection, the tires appeared to be inflated properly and that he did not notice any problem with the steering of the truck. Further, tests conducted by the manufacturer of the tractor indicated that at 50 mph an experienced driver should notice a steering problem when the left front tire pressure dropped to 60 lbs/in $^{2}$, and at 50 lbs/in $^{2}$ an inexperienced driver would be aware that he had a problem. Therefore, the tire pressure of the left front tire is believed to have been at least 60 lbs/in $^{2}$ or higher. If tire inflation pressure was 85 lbs/in $^{2}$, and gross vehicle weight was 65,997 lbs., the load on each of the front tires would have been about 3,799 lbs. The safe tire load rating for that tire at 85 lbs/in $^{2}$ was 5,780 lbs. Therefore, the tire, if normally inflated, was not overloaded. Since there is no evidence to indicate when the nail entered the tire, there is no way to determine when the tire first began to lose pressure and became underinflated.

Rapid Deflation--A State of New Jersey court order obtained by the owner of the truck prevented destructive testing of the tire and prohibited sample specimens to be taken from the tire. This inability to test the failed parts of the tire together with the fact that the inner tube was never found prevented an accurate reconstruction of the failure of the tire.

Based on the presence of the nail in the tire and evidence from a visual examination, the tire failure probably occurred as follows: 7/

"As the tire rotated under load conditions, the point of the nail penetrated the inner tube and caused a slow leak. As the air pressure slowly dropped, the tire running in an underinflated con-

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dition began to heat up in the shoulder area around the circumference of the tire. The heat in the nylon ply cords of the tire increased to the point where the cord-to-rubber adhesion failed. Once this occurred, the cords separated in ribbons in the hottest area, namely, the shoulder area (Figure lla). Under visual examination, the separated cords appeared stringy in separate sections (Figure llb). As the separation continued to grow the rent in the cords and fabric progressed until the separation became large enough to permit the inner tube to blow out through the hole. With the blow out all of the remaining air in the tire escaped and the rim dropped to ride on the inside of the tire, dropping the left front corner of the truck eight inches."

〔图〕插图

Figure llA. Separated ply cords in interior of sidewall of left front tire. Arrow in center of picture indicates where the sharp end of the nail is located.

〔图〕插图

Figure llb. Arrow points to stringy character of separated ply cords in interior of sidewall of left front tire.

"The cords in the tire on the inboard side appeared to be completely broken through the cord body and the interior of the tire sidewall bore shaffing marks. This indicated that after the blow out the tire ran under the rim flange or the pavement in an uneven, wobbly manner." (See Figure 3.)

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The Board believes that the 14-inch cut in the outer sidewall of the tire occurred when the tire impacted the guardrail. The cut ends of the cords in the tire wall support this belief.

Loss of Vehicle Control

The driver stated that when the blow out occurred and when the left front of the vehicle had dropped, steering efforts to counteract the veer to the left were unsuccessful.

The vehicle, traveling at 55 mph (80 ft/sec) when the tire blew out, struck the median curb 112 ft., or approximately 1.40 seconds, later. Granting a normal maximum of 0.75 seconds for driver reaction and 0.35 seconds for brake reaction, the driver would have had 0.30 seconds, or 24 feet, for the brakes to slow the vehicle before it struck the curb. Federal Motor Vehicle Safety Standard 121.8/ specifies a stopping-dis-tance requirement at 55 mph of 219 feet. Based on the 219 feet as the most demanding criteria for stopping distance for a vehicle of this type, it could decelerate at a rate of 14.9 ft/sec$^{2}$. Using this deceleration rate (requiring a full brake application) and the 0.30 seconds available, the vehicle speed when it struck the median curb would have been 52 mph. Had the driver applied only his trailer brakes, the speed would have been 53.4 mph (assuming the 4 trailer brakes would decelerate the vehicle at 1/2 the rate available when all 10 vehicle brakes are applied). Accordingly, significant speed reduction was not attainable before the left front wheel of the truck struck the curb.

The only conceivable corrective actions available to the truckdriver were slowing the vehicle down, and attempting to maintain directional control by turning the steering wheel to the right.

When the left front tire blew out, the wheel, rim, and remaining tire material dropped 8 inches (section height of the tire) onto the road surface, creating a drag on the left side. This caused the tractor to turn to the left into a curve with a calculated radius of 377 feet -- a drastic change of direction for a vehicle as heavy as this at the speed it was traveling. Also, as a result of this change of direction, the truck was subjected to a lateral force of 0.535g. The drag effect or loading couple is difficult to calculate, however, rough calculations suggest that the magnitude of the loading couple and the resultant lateral acceleration was beyond the physical capability of the truck-driver and mechanical advantage of the steering system to overcome. The driver stated that he could not steer the vehicle to the right.

The fact that the driver was not using his seatbelt may have contributed to his inability to control the truck. Had he been wearing the

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seatbelt, he probably would have remained behind the steering wheel and would have had more leverage because he would have been more firmly anchored in his seat. However, it is unknown to what degree this added leverage would have aided the driver in avoiding the accident or reducing its severity as there have been no studies in this area.

Statistics show that it is more safe to remain inside the vehicle than to be ejected. A Bureau of Motor Carrier Safety study (Crash/Injury Ejection Study Commercial Vehicle Accidents 1970-1971, published December 1973) indicated the following: Based on 782 accidents, the fatality rate for ejectees not wearing a seatbelt was 42 percent; the fatality rate for nonejectees not wearing a seatbelt was 28 percent; and for those persons wearing a seatbelt and not ejected, the fatality rate was only 15 percent. Thus, in terms of prevention of fatalities in the wide variety of trucking accidents, there is almost a 3 to 1 advantage for those who wear seatbelts as opposed to those who do not and are ejected. There is almost a 2 to 1 advantage in survival for those who wear a seatbelt as opposed to those who do not when occupants are not ejected.

Front Tire Failures

It is difficult to discover small objects which have become embedded in tires. If the nail had been embedded in the tire before the trip was begun and had been discovered during the pretrip inspection, the truck-driver could have removed it. This nail, however, was so embedded that 20 persons, including experts, examined the tire before the nail was discovered. Inspection cannot prevent all accidents because punctures can occur on the road.

While existing and proposed regulations 9/ which deal with tire safety are important improvements, there is still another aspect of tire safety that is not covered-preventing small and large objects from penetrating the tire body and causing a failure.

There are several ways to approach the problem of front tire failures: (1) Prevent their occurrence initially (if technically possible), (2) develop an automatic correction device not reliant on driver action, (3) develop a device that minimizes the effect of the failure, (e.g., dual chamber safety tire), but may still require correct driver steering and braking action to bring the vehicle to a safe stop, or (4) provide more definitive and realistic driver training with respect to proper evasive action to take than now exists. There will be some situations of sudden emergency in which driver action can prevent an accident. The Safety Board believes that any approach that minimizes driver input (hence less change for human error) would seem the more desirable.

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The BMCS Front Tire Failure Study

The BMCS is testing equipment to control front-tire failures under a contract titled, "Control of Large Commercial Vehicle Accidents Caused By Front-Tire Failures," RFP-103. This work is to be completed by August 27, 1975.

The BMCS will explore front-tire failures in detail and evaluate the effectiveness of at least the following equipment in the prevention of, or lessening of, the severity of front-tire failures:

1. Effects of vehicle loading and weight distribution,

1. Power steering,

1. Safety stabilizer, or equivalent devices,

1. Front-end alignment changes, i.e., increased caster, king-pin inclination changes,

1. Tire type and quality,

1. Tube-type versus tubeless tires,

1. "Safety" tire or wheels,

1. Wheels designed to retain failed tires at high speeds,

1. Radial versus bias-type construction,

1. Improved driver and/or carrier preventive maintenance.

The BMCS Driver Training Study

There is no BMCS regulation requiring that drivers be trained through a formalized training course such as are available at professional driver training schools. The Bureau of Motor Carrier Safety has recognized the need of such training by initiating a research contract titled, "Driver Training Program for Commercial Vehicle Drivers." This program includes 24 areas (e.g. hours of service and drivers logs, braking, shifting, road skills, defensive driving) dealing with the operations of a commercial vehicle. In the area of road skills, there is a section concerned with front-tire failures and how to deal with them. The program will be tested and evaluated in terms of content and to determine the quality of driver such a course would produce.

Driver Training

The instruction given the driver at the Ryder Driver Training School was not objective or definitive. The instruction on braking

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("smoothly") describes only the rate of application, not how much. Further, it is not clear from the technical factors whether the use of brakes, even "smoothly" was the most desirable action to take. Any braking of the front wheels could further increase the drag effect of the deflated left front tire and make corrective action that much more difficult. Blowout training is all classroom discussion. Unless a driver actually experiences a blowout and the after effects on the vehicle, he really does not know what to expect or how to counteract it. The instruction to "not oversteer" could make drivers cautious about full use of steering. How does one know how much to steer in order to not oversteer? Phraseology such as "do not oversteer" and "brake smoothly" are vague and have as many meanings as there are drivers to interpret them.

The Safety Board attempted to gather information on what drivers are (or should be) taught with respect to action after front tire failures. Representatives of the trucking industry, professional driving instructors, and Federal safety experts were surveyed. There was a consensus of opinion that: (1) There is little information available on this subject, (2) what is generally taught now as evasive action is probably as exact as can be stated in light of the absence of exact information and the variation in vehicle configuration, and (3) that an actual driving experience involving a forced blowout on a skid pad would be valuable.

Many questions need to be answered with respect to driver training. Can drivers be taught to control trucks with front tire failures at all speeds? Can more definitive information on this subject be developed? Is it necessary to subject drivers to an actual blowout situation?

Hopefully, answers to these questions and a meaningful recommendation for a front tire failure situation will be forthcoming from the BMCS driver training study.

Performance of the Median Barrier and Guardrail

The median guardrail offered little resistance when the truck struck and crashed through it. In fact, the truck continued on, struck the car and the bus, and crashed through the guardrail on the opposite side of the highway. This is not surprising because the standard W-beam guardrail, such as that found on the Turnpike and a majority of the Nation's highways is not designed to retain heavy vehicles. In 1962, the Highway Research Board suggested the use of a 4,000-lb. test vehicle at an impact angle of 25° and an impact speed of 60 mph. These criteria, which omitted adequate protection against trucks, have been accepted by the American Association of State Highway Transportation Officials (AASHTO) and the Federal Highway Administration. They have become the basis for the various States to qualify for Federal-aid funds for median and roadside guardrail construction. Consequently, guardrail design has been limited to the retention of the typical American automobile under the crash conditions previously specified.

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The Safety Board recognizes the inability of guardrail designs to retain heavy vehicles and has spoken specifically to this in several of its reports. 10/

At present, the Federal Highway Administration has an extensive research and development project, "Advanced Vehicle Protection Systems," which includes the heavy-vehicle problem. According to FHWA, the project's objective is "to establish design standards to obtain adequate guardrails, bridge rails, and median barriers, and to devise adequate structural solutions for other roadside obstacles in collisions with heavy vehicles. Designed specifically to contain heavy vehicles, the new traffic barriers are intended to prevent penetration, redirect vehicles, and reduce accident severity for all vehicle-barrier collisions."

The Safety Board views this project as a significant step forward in the development of new barrier systems that will protect all users of the highway and urges the FHWA to continue and expedite its efforts.

CONCLUSIONS

1. The penetration of the left front tire and tube by a nail probably led to the failure of the tire, which led to the loss of control of the vehicle by the driver.

1. It is doutful that the truckdriver could have seen the nail in the tire at routine inspection because many experts examined the tire later before it was found.

1. When the truckdriver first heard the loud noise, he did not know that it was a blowout or what direction the noise came from. He was first aware of the blowout when the left front end of the tractor dropped and the truck began to veer to the left.

1. The left front tire was not overloaded.

1. Of the several approaches to front tire failures, those that require a minimum amount of driver action seem the most desirable.

1. The truckdriver took the recommended evasive action in response to the tire failure, but was unsuccessful.

1. Once the tractor began to veer to the left the ability to turn the steering wheel was beyond the capability of the truckdriver.

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1. The truck driver did not have sufficient time to reduce the speed of the vehicle to a point where evasive actions may have been effective.

1. Had the truckdriver worn his seatbelt he would have been secured to the seat more firmly and might have been able to control his truck better after the initial impact with the curb.

1. The Ryder School did not provide behind-the-wheel training in counteracting the steering effects of blowouts; however, it is questionable whether training alone could have prevented the steering effect in this accident.

ll. Answers to questions dealing with driver training with respect to controlling front tire failures must await completion of a BCMS study in this area.

1. The W-section guardrail installed on the median and shoulders of the Turnpike was not designed to retain and redirect heavy commercial vehicles, traveling at Turnpike speeds.

1. The automobile driver and the busdriver had no opportunity to take evasive action to avoid the errant truck.

PROBABLE CAUSE

The National Transportation Safety Board determines that the probable cause of the accident was the sudden deflation of the left front tire on the tractor which caused the driver to lose control of the vehicle. The sudden deflation resulted from a gross failure of the tire sidewall due to under inflation caused by an undetected nail puncture.

Contributing to the fatalities and injuries was the inadequacy of the median guardrail to prevent the tractor-semitrailer from entering into the opposing lanes of traffic.

RECOMMENDATIONS

The National Transportation Safety Board recommends that the Federal Highway Administration:

1. Upon completion of the research dealing with the development of a commercial driver training course, distribute such training course information to all professional commercial driver training schools. (Recommendation H-75-9)

1. Amend the Federal Motor Carrier Safety Regulations (Section 391.11) to require that all candidate drivers be familiar through

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formal training with such driving emergencies as front tire failures, brake fade, jackknife situations. (Recommendation H-75-10)

1. Expedite that portion of the FHWA research project, "Advanced Vehicle Protection Systems," that will provide data for design of new barrier construction and improvements to existing systems. Dynamic vehicle impact tests should be made using both intercity buses and heavy trucks. (Recommendation H-75-11)

BY THE NATIONAL TRANSPORTATION SAFETY BOARD

/s/ JOHN H. REED Chairman

/s/ FRANCIS H. McADAMS Member

/s/ LOUIS M. THAYER Member

/s/ ISABEL A. BURGESS Member

/s/ WILLIAM R. HALEY Member

March 12, 1975

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APPENDIX A

Table 1

Front Tire Failure Accidents - Property Carriers

Source: Commercial Vehicle Front-Tire Failures, U.S. Department of Transportation, Federal Highway Administration, Bureau of Motor Carrier Safety, Washington, D. C. 20590

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APPENDIX B

INSPECTION OF LEFT FRONT TRUCK TIRE

〔图〕OOEPARTENAMERICA *CZITEUSTATESOf\n

U.S. DEPARTMENT OF TRANSPORTATION

NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION WASHINGTON, D.C. 20590

IN REPLY REFER TO: N41-33

Mr. A. L. Schmieg National Transportation Safety Board FAA Building Room 817 E Washington, D. C. 20591

Dear Mr. Schmieg:

At your request we had Safety Standards Engineer, Mr. John A. Diehl, meet with Mr. George Larsen, Jr., of your office, on November 7, 1973, at Exit No. 4, New Jersey Turnpike, to inspect a tire and rim that was involved in an accident.

Inspection observations:

I. Tire Data

a. Tire and rim located at barracks three miles north of Exit No. 4.

Tire Size Designation 10.00-20, 12-ply rating: Load for front wheel useage 5,780 pounds at 85 psi cold inflation pressure. Gross Axle Weight Rating 11,560 pounds.

b. Brand Name

Super Tire Engineering Company

Made in Israel 12-ply rating.

c. Inspection of Tire

A nail was found in the bottom of the second groove in from the side of the tire that was not burned. It protruded approximately k of an inch from the bottom of the groove. An inspection inside the casing showed that the nail did not protrude into the tire whereby it could be found by passing a finger or hand over the opening. The size of the hole was very small and hardly discernable. The nail appeared to be the size of a nail used in making vegetable crates. The nail

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can be found on a radial line from the letter "N" in the word "traction." However, as the tire was rotating under load the nail penetrated the inner tube and caused the tire to deflate, as a slow leaker. When this occurred the tire pressure dropped and the tire heated up in the shoulder area around the circumference of the tire. The cords in the tire on the burned side were completely broken through the cord body. The cords were broken because the nail had caused a slow leak and the tire was running under inflated. Underinflation caused the heat in the cord body to rise to the point where the rubber to cord adhesion failed. Once this occurred the cords separated in bundles or ribbons in the hottest area, namely the shoulder. The cords appeared stringy, in separate sections and as the separation continued to grow, the rent in the fabric or cords progressed, until a separation large enough caused the remaining air pressure in the inner tube to expel it from the tire through the destroyed parts of the cord body.

The cord failure sometimes represent the "strings" of a mop. There are some cords that hold together and other cords become separated giving a stringy look to the cord body in the failed area.

There was another cut in the tire on the opposite side of the tire approximately 14 inches long. This cut apparently occurred when the tire and wheel impacted the guard rail. The cut ends of the cords in the cord body definitely indicated this. This was not the cause of the tire failure, because it shows as an impact cut.

The cords in the tire on the burned side were completely broken through the cord body. This indicated that after the inner tube was blownout the tire ran on the rim flange or the pavement, and thus also further destroyed the cords just below the shoulder in the cord body except for a length of approximately ten inches.

d. Inspection of the flap

The flap was in good condition and showed no evidence that the inner tube had been wrinkled in the flap area, at the time of mounting the tire, tute, and flap to the rim. The flap splice was smooth and the edges were round and of such a nature that the edges of the flap, would not damage or cut the inner tube. The valve hole in the flap revealed that the valve had abraded the fabric surrounding the valve hole, as the inner tube was lost through the broken part of the tire cord body.

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e. Inner tube

The inner tube was never located after the accident. However, it is the opinion of the Safety Standards Engineer that the inner tube caused the tire failure, because there were no valve marks inside the tire and this indicates the inner tube failed first, causing the rapid loss of air, yet in a revolution or two there was still enough pressure to cause the flange to become disengaged and impacted the adjacent vehicle. The tire running a short distance caused the cord body to fail and there was still enough pressure to expell the inner tube from inside the tire.

f. Rim and Demountable Flange

The rim body had no identification or stamping that would reveal the manufacturer. The rim was bent out of round and the flange as well. However, the wheel was placed on the floor and one end of the flange was mounted in the gutter slot and it matched the gutter contour perfectly, indicating the demountable flange was the correct flange for the rim.

The flange had the following data stamped near the edge of the flange:

20-7.5 8-A-3-190 followed by the Tire and Rim Associa- nping symbol, but the letter indicating the rer was not discernible, making it impossible nine the rim manufacture.

The rim and flange were the correct size and contour for the tire size designation.

II. Tire Data - Exit No. 8, New Jersey Turnpike

The remains of the tractor were located in the guarded yard at Exit No. 8. The right front tire and spoked wheel assembly, 6 spokes, was still mounted to the axle, also bent, but still inflated. The tire design was the same tread design as that of the failed left front wheel assembly.

The tire identification number of this tire was CD 2J 181E 113. This tire had approximately 3/16 remaining tread depth in the groove near the centerline of the five-rib tread pattern and matched that of the tire first inspected.

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The letters CD are the plant code for The Alliance Tire and Rubber Company, Hadera, Israel. The 2J indicates tire size code for the 10.00-20 tire size designation. The 113 indicates that this tire had been manufactured the eleventh week of 1973. These data were obliterated on the left front tire because of the burned condition of the tire.

It was stated that you have a man in your group who has all the data on the 1970 Mack Tractor that was involved in the accident, and from Mack Truck Company, the wheel and rim source at the time of manufacture can be determined.

If we can be of further assistance, please let us know.

Sincerely,

E. T. Driver, Director Office of Operating Systems Motor Vehicle Programs