15-Passenger Child Care Van Run-Off-Road Accident Memphis, Tennessee April 4, 2002

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15-Passenger Child Care Van Run-Off-Road Accident Memphis, Tennessee April 4, 2002

〔图〕插图 Highway Accident Report

NTSB/HAR-04/02

PB2004-916202

Notation 7623

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Highway Accident Report

Contents

Acronyms and Abbreviations $\ldots$ vi

Executive Summary vi

Factual Information .................................................................... 1

Accident Narrative 1

Injuries 3

Medical and Pathological Information .................................................................................................................................... 3

Survival Aspects 4

Intrusion and Restraints ...........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

Emergency Response 5

Toxicological Tests ................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

Driver Information .................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

Vehicle and Wreckage Information 7

Highway Information .................................................................................................................................... 9

Barrier System .................................................................................................................................. 12

Accident History $\ldots$ 13

Physical Evidence .................................................................................................................................................................................................. 14

Weather Information 18

Operational Information $\ldots$ 18

Simulations 19

Vehicle Dynamics Simulation $\ldots$ 19

Occupant Kinematics Simulation 20

Bus Definitions 23

School Bus .........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

Multifunction School Activity Bus 23

School Bus Fatality Data $\ldots$ 23

Child Care Transportation Laws and Guidance 24

Findings of Tennessee Committee on Child Care Agency Transportation Safety ... 24

Child Care Transportation Laws in Tennessee .................................................................................................... 25

Child Care Transportation Laws in Other States .................................................................................................................................... 25

Head Start Transportation Law $\ldots$ 28

National Highway Traffic Safety Administration Interpretation 29

Booster Seats 29

Roadside Barrier Guidelines ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

Previous Recommendations $\ldots$ 30

Analysis 31

Introduction $\ldots$ 31

Accident Discussion .................................................................................................................................. 32

Driver's Condition .................................................................................................................................. 33

Child Care Transportation .................................................................................................................................. 36

Vehicle .................................................................................................................................... 36

Restraint Usage .................................................................................................................................. 37

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Highway Accident Report

Factual Information

Accident Narrative

On April 4, 2002, about 8:19 a.m., a 15-passenger Ford E-350 van, driven by a 27-year-old driver transporting six children to school, was southbound in the left lane of Interstate 240 (I-240) in Memphis, Tennessee. (See figure 1.) The van was owned and operated by Tippy Toes Learning Academy (Tippy Toes), a private child care $^{1}$ center. A witness driving behind the van stated that it was traveling about 65 mph when it drifted from the left lane, across two other lanes, and off the right side of the roadway. (See figure 2.) She said that she did not see any brake lights. The van then override the guardrail and continued to travel along the dirt and grass embankment until the front of the van collided with the back of the guardrail and a light pole. The rear of the van rotated counterclockwise and the front and right side of the van struck the bridge abutment at the Person Avenue overpass before coming to rest. (See figure 3.) The distance traveled by the accident van from the point where it left the shoulder of the roadway to the final collision with the bridge abutment was approximately 189 feet. The driver was ejected through the windshield and sustained fatal injuries. Four of the children sustained fatal injuries, and two were seriously injured.

〔图〕Chefsea145140Ave70NorthSMemphisNationa!Macon Rd34014BerclairPinchDistrictSam Cooper70BivdPoplarAveTENNESSEEMemphisMidtow

Figure 1. Area map.

Factual Information

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〔图〕-\n

Figure 2. Approximate path of van, indicated by the arrow (the roadway continues to curve beyond the bottom of the picture, where the van began its departure).

〔图〕Norris Ro\n

Figure 3. Van at final rest.

Factual Information

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Injuries

Table 1. Injuries.$^{2}$

Medical and Pathological Information

The driver sustained multiple fractures to left ribs 1 through 9, skull fractures, a shear injury to the brain stem, internal injuries, a fractured right ulna, and multiple abrasions to the whole body. As for the fatally injured children, the 6-year-old girl lap/shoulder belted in the right-front seat (see figure 4) sustained depressed skull fractures, fractures of the lower extremities, and multiple contusions, lacerations, and abrasions to the head and lower extremities. The unrestrained 8-year-old boy seated in the center of the first row sustained a depressed fracture to the occipital bone, a right femur fracture, and multiple abrasions and contusions. The unrestrained 6-year-old girl seated on the right side of the first row sustained open, depressed skull fractures, a cervical fracture, and multiple abrasions to her extremities. The unrestrained 9-year-old boy seated in the center of the second row $^{3}$ sustained skull fractures, a left rib fracture, a fracture to the right upper extremity, and multiple abrasions.

Factual Information

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〔图〕*乙\n 〔图〕3456789101112131415\n

Figure 4. Seating chart (ejected; shading indicates fatal injury).

Two other children sustained serious injuries. An unrestrained 10-year-old boy seated on the left side of the first row sustained upper torso fractures, internal injuries, and facial lacerations and abrasions. Another unrestrained 10-year-old boy seated on the left side of the second row sustained brain and lung injuries.

Survival Aspects

Intrusion and Restraints

The driver was not wearing his lap/shoulder belt and was ejected during the impact with the bridge abutment. The impact with the light pole and bridge abutment pushed the dashboard into the right-front passenger's seat, so that part of the dashboard was touching

Factual Information

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Highway Accident Report

Due to the severity of the accident damage, investigators were unable to determine whether the cruise control was on at the time of the accident.

Investigators extracted diagnostic codes from the van's electronic crash sensor (ECS), antilock brake module, and powertrain module. The codes that registered were consistent with the crash event, according to Ford personnel. Siemens (the ECS manufacturer) further analyzed the ECS because it has the capability of recording a crash pulse. However, battery power to the ECS had been cut off before a complete crash pulse could be written to the ECS. Five milliseconds of data were recorded; the remaining 65 milliseconds that are typically written were blank. No useful data could be extracted to determine the crash pulse.

The van's exterior had direct impact damage to the front, including the bumper, grill, hood, lights, right-front fender, and a broken windshield. (See figure 5.) The base of the right A-pillar was bent backwards approximately 15 inches to within 12 inches of the front seat. The right side also had impact damage to both doors and the wheel well area. The maximum crush to the right side was about 24 inches at the roofline. The direct damage extended about 195 inches from the right-front fender to the right-rear quarter panel. The left side had a bent driver doorframe and body wrinkles in the front and rear wheel well areas. The front of the roof was bowed upward. No damage occurred to the rear of the van. The wheelbase was 133 inches on the left and 124 inches on the right. The overall length of the van was 232 inches on the left; this length was reduced to 224 inches on the right.

〔图〕插图

Figure 5. Van damage.

Factual Information

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Highway Accident Report

The interior damage generally corresponded to the exterior damage along the right side of the van. The front and side of the van intruded into the front seat passenger's space. (See figure 6.) The lateral floor weld behind the front seats on the passenger side separated and buckled upward.

〔图〕插图

Figure 6. Front passenger seat intrusion.

Highway Information

The accident events originated in the southbound lanes of I-240 in southwest Memphis and concluded approximately 189 feet later on the north side of the Person Avenue overpass. (See figure 7.) I-240 is an urban principal arterial highway and, in the vicinity of the accident site, was a six-lane divided highway with concrete pavement. Each side of the highway consisted of a 2.5-foot wide concrete drainage channel, an 8-foot-wide outside shoulder, three 12-foot-wide travel lanes, and a 13-foot-wide inside shoulder. All pavement markings met the requirements specified in the Manual on Uniform Traffic Control Devices.$^{8}$

Factual Information

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〔图〕OutsideshoulderMilepost27.6Longitudinalroadside406001020barrierFEETInsideshouldeTravelanesLight poleConcretemedian barri

Figure 7. Highway at accident site.

A 2-foot-wide, 42-inch-high median concrete barrier separated the north- and southbound traffic lanes. A 165-foot-long blocked-out W-beam (strong post) semirigid longitudinal roadside barrier system (guardrail) was located about 2.5 feet west of the right shoulder adjacent to the concrete drainage ditch on a 3:1$^{9}$ grassy embankment and was attached to the Person Avenue concrete bridge abutment. The southbound lanes had a 2.5-percent descending grade and the roadway transitioned from a straight alignment to a 3-degree horizontal left curve at a point 440 feet north of the beginning of the barrier. (See

Factual Information

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figures 8 and 9.) A 38-foot-high aluminum light pole on a breakaway base was approximately 20 feet north of the bridge abutment and about 4 feet west of the guardrail.

〔图〕-\n

Figure 8. Overhead view of roadway curvature.

〔图〕-\n

Figure 9. Roadway curvature from ground level.

Factual Information

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Highway Accident Report

〔图〕插图

Figure 10. Guardrail and terminal unit.

The longitudinal section consisted of a 165-foot single W-beam guardrail; the effective length was 160 feet, since 5 feet was attached to the bridge abutment. Metal posts with wooden blockouts supported the W-beam guardrail.$^{11}$ The posts were approximately 75 inches apart along the semirigid portion. The section prior to the bridge abutment provided for the transition from a semirigid longitudinal section to a rigid section to prevent pocketing.$^{12}$ The posts along the rigid section of the barrier were closer together (approximately 36 inches apart).

Accident History

TDOT and the MPD provided accident records for the section of 1-240 near the accident scene. For an area about 0.5 miles on either side of the accident location, TDOT reported 1 fatal accident resulting in 1 fatality, 48 injury accidents resulting in 85 injuries, and 91 accidents resulting in property damage only between 1997 and 2001. Of these accidents, 43 (31 percent) involved collisions with fixed objects. The MPD accident data, which encompassed an area at or near the accident site,$^{13}$ reported a total of 34 accidents between 1997 and 2001, 25 of which occurred in the southbound lanes. The MPD data showed two fatal accidents similar to this accident. One occurred in 1998, when the driver

Factual Information

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〔图〕N40608001020100FEETRoadwayMileposdeparture27.6and tirefurrowFirst impactBeginning ofscrapes toroadsidebarrierAdditional

Figure 11. Physical evidence.

Factual Information

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〔图〕插图

Figure 12. Guardrail damage, light pole base (indicated by arrow), and bridge abutment scrapes.

The 38-foot light pole was mounted on a 14-inch-square breakaway base $^{14}$ located at ground level. The light pole's mounting plate was connected to the breakaway base by four 4.5-inch-long vertical nut and bolt assemblies. (See figure 13.) After the accident, the light pole came to rest in the center lane of southbound I-240. The base of the breakaway fixture was still in the ground; three of the four mounting nuts were still attached to the base, but the mounting nuts had fractured as designed, separating the light pole's mounting plate from the breakaway base. (See figure 14.) An indentation was noted 17.5 inches above the pole's mounting plate; scrapes and paint transfers extended from the mounting plate to 57 inches above the plate.

Factual Information

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〔图〕插图

Figure 13. Exemplar light pole plate and breakaway base.

〔图〕插图

Figure 14. Light pole breakaway base mounting plate with fractured mounting nuts.

Factual Information

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〔图〕Model step\n

Figure 15. Seat belt position with and without a booster seat (6-year-old Hybrid III dummy).

〔图〕插图

Figure 16. 10-year-old dummy with lap/shoulder belt.

Factual Information

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Table 2. Child care transportation laws. (Check mark indicates that the State's law addresses a particular area.)

Factual Information

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Head Start Transportation Law

Head Start is a Federal child development program serving low-income children from birth to age 5 to increase their school-readiness. On January 18, 2001, the DHHS, which administers the program, issued a rule, partially based on a Safety Board recommendation,$^{33}$ concerning the transportation of children by Head Start agencies. Beginning January 18, 2006, Head Start agencies providing transportation to children enrolled in their programs must use school buses or allowable alternative vehicles that are equipped with height- and weight-appropriate restraint systems; these restraint systems must be used at all times. Effective January 20, 2004, one bus monitor must be on board Head Start agency vehicles at all times. Further, all drivers must possess a commercial driver's license and be examined by a licensed doctor to establish their physical ability to perform the job. Finally, all drivers and monitors must receive recurrent training in vehicle and passenger safety.

Analysis

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van had rotated approximately 19 degrees toward the right and collided with the light pole affixed to a breakaway base unit (location 5). This collision caused the van to rotate further, such that it was oriented about 45 degrees from the initial direction of travel when it struck the bridge abutment, about 20 feet beyond the light pole (location 6). The front right side of the van sustained the greatest amount of damage due to the force of the collision. Because the van had begun to roll back toward the right after the collision with the light pole, the upper portion of the right side body panels incurred the greatest impact deformation.

〔图〕TENTSB/\n

Figure 17. Path of van.

Driver's Condition

The driver's condition was evaluated to determine the role that it played in the accident. The driver's postaccident toxicological tests indicated that he had used marijuana recently; based on the concentration of THC and THC-COOH in the driver's blood, the estimated time of marijuana consumption was anywhere from 13 minutes to 3 hours before the accident.$^{48}$ Since THC begins to metabolize almost immediately after use, the presence of THC in the driver's blood indicated that the hallucinogenic compound of marijuana had not completely metabolized and was still influencing the driver's performance.

Analysis

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〔图〕插图

Figure 18. True runout length on curve.

Because of the horizontal curve before the bridge abutment, the length of need of the guardrail should be calculated to account for vehicles that leave the roadway tangent to the curve, as the accident vehicle did. AASHTO states in one of its design examples $^{76}$ that when a vehicle leaves the road on the outside of the curve (as in this accident), it generally follows a tangential path. In such cases, the tangent line from the curve to the clear zone or outside edge of the hazard should be used instead of the theoretical runout length.

Because of the curvature of the roadway, a vehicle can depart the roadway at a distance further from the hazard than that predicted by AASHTO's recommended runout length. When a vehicle "straightens out" the curve, it departs the roadway further from the hazard but still needs to be redirected or provided room to stop. When this occurs, the vehicle can completely miss the barrier system designed to protect against the hazard, as was the case in this accident and others. MPD records indicate three fatal (including this accident) and two property damage accidents at this location between 1997 and 2002 in which vehicles became trapped behind the guardrail.

The steep grade of the backslope and the wall of the bridge abutment, when combined with the barrier, created a trap. Once trapped behind the barrier, even had the driver tried to steer to avoid striking the abutment, he would not have been able to return to the roadway because the van was trapped between the guardrail and the backslope, effectively directing the van into the bridge abutment. However, with sufficient stopping distance, a vehicle could stop before striking the bridge abutment. Thus, the runout length of the barrier also needs to take into consideration situations in which no clear zone is available to a driver who gets trapped behind the barrier. In the simulation, the driver would have had 1.8 seconds to try to bring the vehicle under control from the time he

Analysis

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Highway Accident Report

departed the roadway. This is insufficient time to stop a vehicle, and the slope does not allow the driver to steer away from the barrier.

In the simulation, a vehicle traveling at 65 mph in the left lane and continuing in a straight path tangent to the curve, instead of following the curvature of the roadway, would need at least 40 more feet of guardrail with the same end treatment, or 10 feet more with a different end treatment, to redirect the vehicle onto the roadway. Using AASHTO's formulas and a runout length of 480 feet (based on the 85th percentile speed of 70 mph) and plotting the trajectory of a vehicle that leaves the roadway tangential to the curve, the barrier system's length of need is 293 feet, exceeding the existing barrier's length by 133 feet, not including the end treatment. (See figure 19.) By extending the barrier, the likelihood of an errant vehicle impacting the barrier system and being redirected away from the bridge abutment increases. For a driver trapped behind the barrier, the additional length would provide the opportunity to stop before colliding with the bridge abutment.

〔图〕Additional length required forthe length of need(does not include the terminal end)Length of existing barrier system480-

Figure 19. Length of need based on speed and roadway curvature.

The Safety Board concludes that given the roadway curvature and the lack of a clear zone, the barrier at the accident site was not long enough to prevent a vehicle that departed the roadway from going behind the barrier or to allow an errant vehicle to recover before striking the bridge abutment. AASHTO's Roadside Design Guide does not specifically address these types of situations or direct the highway designer to examine the need for longer runout lengths if the conditions could contribute to a vehicle becoming trapped behind the barrier or if the roadway curves. The Safety Board believes that AASHTO should modify the guidance contained in the Roadside Design Guide to clearly provide designers with information on the design of roadway barrier systems in situations where the roadway curves or where the terrain, hazards, and barrier system could trap an errant vehicle behind the barrier system. The Safety Board will ask AASHTO to inform its members of the circumstances of this accident and of the importance of considering roadway curvature and terrain configurations in the design of barrier systems.

Conclusions

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Probable Cause

The Safety Board determines that the probable cause of this accident was the absence of oversight by Tippy Toes Learning Academy and the driver's inability to maintain control of his vehicle because he fell asleep, quite likely due to an undiagnosed sleep disorder; the driver's marijuana use may also have had a role in the accident. Contributing to the accident was the Tennessee Department of Human Services' lack of oversight of child care transportation. Contributing to the severity of the injuries were the use of a 15-passenger van to transport pupils, the nonuse of appropriate restraints, and the design of the roadside barrier system.

Appendix B

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Table B-1. State compliance with safety recommendations.

Appendix B

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