Showing papers on "Rollover published in 1992"

Speed actuated rollover advisory signs for trucks on highway exit ramps

Abstract: Special truck rollover-warning signs were examined for effectiveness in slowing tractor-trailer trucks to a speed below that associated with rollover on highway exit ramps. Advisory speeds were verified for trucks at three highway exit ramps with high truck rollover crash frequencies; rollover-warning signs specific to trucks were posted to supplement the standard speed advisory signs already in place. The supplemental rollover-warning sign was equipped with a yellow light that was triggered to flash for every second tractor-trailer truck traveling above a predetermined ramp approach speed. Mean speeds at midramp associated with the flashing sign were lower than for the nonflashing sign. Although the flashing signs did not significantly increase the number of trucks in strict compliance with maximum safe speeds, they did significantly reduce the number of trucks that were traveling more than 5 mph and 10 mph faster than the calculated maximum safe speed. These findings suggest that speed-actuated rollover advisory signs specific to trucks may reduce truck rollover crashes at highway ramps.

A statistical analysis of vehicle rollover propensity and vehicle stability

Abstract: This chapter on the statistical analysis of vehicle rollover propensity and vehicle stability is from a comprehensive textbook on occupant and vehicle responses in rollovers. The author documents the accident data collection, processing, and analysis methodology used by the National Highway Traffic Safety Administration (NHTSA) in a major agency investigation of the rollover propensity of light duty vehicles. These efforts were initiated in response to two petitions for rulemaking requesting the development of a standard for rollover stability. Logistic regression models were used to investigate the ability of a number of stability measures to predict vehicle rollover propensity, while accounting for a number of driver and environmental factors. The results demonstrate the existence of a relationship between measures of roll stability and a vehicle's propensity to roll over in real-world single-vehicle accidents. Of the three basic roll stability metrics evaluated (tilt table ratio, static stability factor, and side pull ratio), the tilt table ratio appeared to provide the greatest explanatory power, but only by a slight margin over the static stability factor.

Heavy vehicle size and weight - test procedures for minimum safety performance standards

Abstract: This report describes two regulatory scenarios pertaining, respectively, to the basic resistance to rollover and the obstacle avoidance maneuvering capability of longer and heavier commercial vehicles. At the time of the study, new legislation that could allow the nationwide introduction of the vehicle combinations heavier than 36,400 kg (80,000 lbs) and longer than twin, 8.5-meter (28-foot) doubles was under consideration.

Mechanisms of injury and biomechanics: vehicle design and crash performance.

Abstract: This paper reviews briefly the early evolution of the subject of the biomechanics of impacts. Some examples of rule-making of vehicle crash performance are cited to illustrate the need for evaluation of all design changes and regulations in the real world of crashes and injuries. Some background data on the relative frequencies of casualties and types of collisions are given to establish overall priorities. Mechanisms of injuries in frontal collisions for unrestrained and restrained occupants are described to illustrate the relationships between interior localized contacts and injuries to the lower limbs, the chest, and the head. Kinematics of occupants in angled, lateral, and rear collisions are reviewed together with the related injury mechanisms, and rollover crashes with and without seat belt use are mentioned. Motorcyclist and pedestrian kinematics and some of the desirable characteristics of the vehicle exterior are described together with the unfortunate consequences of the current bumper standards. In summary the paper aims to be a general review of crash kinematics and general mechanisms of injury.

Estimating Truck’s Critical Cornering Speed and Factor of Safety

Abstract: Fully laden trucks are prone to rollover when exceeding a critical cornering speed. After an accident, authorities, both highway engineers and the police, often need to establish a vehicle's speed from tire marks and other physical evidence. This paper outlines the relative precision of equations of varying complexity used to estimate a truck's critical rollover speed based on tire marks. An error analysis is compared with a limited tachometer data base to evaluate the accuracy of the speed-estimating equations. The study shows that for most situations with fully laden, rigid trucks, the simple lumped-parameter model gives an acceptable estimate of the rollover speed for highway design engineers and the police. Also, a review of the lateral acceleration generated by a vehicle negotiating a minimum-radius curve found that the acceleration is very close to the level needed to tip over a truck. Based in part on these findings a method for developing a reasonable estimate of level of safety is discussed.

Motor vehicle rollover protection device

Abstract: A motor vehicle rollover protection device is provided at each side of the vehicle and can be raised out of a lowered position in one plane into a supporting position and fixed in this supporting position. At least one of the rollover protection devices is arranged to extend approximately in the longitudinal direction of the vehicle and on each of the two sides of a vehicle body. In the lowered position, the device is sunk into a vehicle side wall.

Pivotable rollover bar for motor vehicles

Abstract: A pivotable rollover bar for motor vehicles, in particular for four-seater convertibles, which, bent in the shape of a U, surrounds the rear seating area of a passenger compartment in a lowered rest position. The rollover bar can be pivoted by a drive about lateral bearings on a vehicle body, about a transverse axis of the vehicle, into a raised operative position in which its crossbar spans the interior of the passenger compartment. The rollover bar is provided on its lateral limbs with a flattened portion on the side facing the interior of the passenger compartment, this flattened portion enlarging the interior or the passenger compartment at the sides of the seat. At least one supporting tube projects from the rollover bar towards the vehicle body, the supporting tube being displaceable together with the rollover bar and being guided in a guide in the vehicle body and positioned to take up forces in the transverse direction of the vehicle.

Prevention of brain trauma by legislation, regulation, and improved technology: a focus on motor vehicles.

Abstract: More than half of all brain trauma is caused by motor vehicle crashes. Prevention strategies that reduce the likelihood of motor vehicle crashes or injuries to occupants will also prevent trauma. Many effective strategies have yet to be applied on a large scale. Roadway design improvements such as removal of fixed objects from roadsides, widening roadside recovery zones, installing dividers between opposing lanes of traffic, and replacing fixed utility poles with breakaway designs, have been effective in reducing crashes and injuries. Driver measures of documented benefit include the 55 mph speed limit, safety belt use laws, 21 year legal drinking age, administrative license suspension for drinking drivers, and driving curfews and postponement of licensure for teenagers. Motor vehicle safety has improved greatly since the National Highway Traffic Safety Administration began regulating vehicle design. Significant design requirements include lap and shoulder belts in front seat positions, and, more recently, automatic safety belts or air bags in front seat positions, head restraints in front seat positions, reinforcing side and roof beams, and the center-mounted brake light. The most significant future advance will be the provision of full front seat air bags in all passenger vehicles. As much as one-quarter of brain trauma can be prevented or reduced in severity by this measure alone. Further safety requirements should include head restraints in rear positions, a-pillar, b-pillar, and roof padding, antilock brakes, and a vehicle rollover standard. Language: en

Evaluation of nhtsa light vehicle handling simulations. final report

Abstract: This report contains evaluations of four light vehicle stability and control simulations developed for the National Highway Traffic Safety Administration (NHTSA): FOROL developed by Dynamic Research Inc., the "Intermediate Maneuver Induced Rollover Simulation" (IMIRS) and the "Advanced Dynamic Vehicle Simulation" (ADVS), both developed by the University of Missouri, and "Vehicle Dynamics Analysis, Non-Linear" (VDANL) developed by System Technology, Inc. The focus of these evaluations is each simulation's ability to accurately predict light vehicle responses during flat road handling and crash avoidance maneuvers. Each simulation is first described on an analytical basis. The overall modeling approach is described along with detailed descriptions of the modeling of the vehicle subsystems. For each simulation, any areas found to be inadequately modeled are reported. The ability of each simulation to predict flat road vehicle responses is evaluated by comparing the simulation predictions to experimentally measured vehicle responses. These comparisons are done in both the time and frequency domains. The intent of this report is only to evaluate the capabilities of each simulation in its current form, and recommend a direction for future work in this area. It is not the intent of these evaluations to determine if the developers of the simulations met the requirements of their contracts.

Behaviour of articulated vehicles on curves

Abstract: This article describes a study undertaken to assess the feasibility of providing the driver of an articulated vehicle with information on the roll-stability of the trailer unit. The study involved the investigation of the in-service characteristics of articulated vehicles as they approach the roll-threshold. The ARRB tilt deck was used to determine the roll-threshold level for each of the five test vehicles in the laden condition. The vehicle speed, the effective radius of curvature of the prime-mover travel, and the superelevation of the road surface (cross-slope) were calculated from the recorded data. Analysis of the data showed that drivers i) generally operate within a relatively narrow band of their vehicles' roll- limit (between 50-60%), and ii) adjust their steer path and entry speed through curves to operate within that narrow band. A relationship between the proportion of roll- threshold generated and the critical time available to advise the driver of imminent rollover has been developed. (A) For the covering abstract of the conference see IRRD 852196.

The roll-behaviour of trucks around curves

Abstract: ARRB undertook a study to assess the feasibility of providing the driver of an articulated vehicle with information on the roll-stability of the trailer unit. The study involved the measurement of the roll-behavioural characteristics of articulated vehicles as they approach the roll threshold. Five articulated vehicles were instrumented to measure: (i) the lateral acceleration at the rear of the trailer, (ii) the lateral acceleration and yaw rate in the prime-mover, (iii) the vertical load shift on both sides at the mid-point of the trailer suspension, (iv) the distance and elapsed time from the start of the trip. The vehicle speed, steer path radius and road surface cross-slope were calculated from the recorded data. Results from this study establish that: No single parameter significantly correlated with roll-stability; Sufficient time is available to warn drivers of imminent rollover; Negotiating curves, vehicle/drivers approach vehicle roll-limits at a constant rate; Generally, drivers adjust the vehicle speed and steer path to operate within a narrow band of the vehicle's roll-threshold. A prototype Rollover Warning Device is now being developed.

Australian design rules: improving bus safety

Abstract: The Australian Design Rules (ADRs) set down the performance and design requirements for motor vehicle safety and have been in place since 1969. The ADRs are amongst the most stringent in the world and are over 60% aligned with international standards. The Federal Government has been working on improved ADRs for heavy vehicles since 1988. By the time of the two tragic crashes in NSW in late 1989, several new or amended ADRs had either already been approved or were being finalised. This package included bus rollover strength, improved seat strength padding for coaches and speed limiting of heavy vehicles. These accidents raised concerns over the access, size and placement of emergency exits together with a need for improved occupant restraint. The rollover crash in Queensland added the topic of laminated glass in side windows to prevent occupant ejection.

Sensitivity analysis of the tilt table test methodology. final technical report

Abstract: The study was performed by UMTRI for the Motor Vehicle Manufacturers Association. The study was undertaken in order to investigate the sensitivity of tilt table measurement results to variables associated with the methodology and/or facility. To do this, 113 tilt table measurements of a single test vehicle were conducted at one facility. A number of facility and procedural parameters were deliberately altered during the testing to determine the sensitivity of the method to these changes. The results of the program showed: (1) Changes in trip rail geometry (which included the use of one-inch and two-inch high rails and locations of the rails at zero, one, or two inches from the tires) altered measurement results by as much as 5%. (2) Significant changes in surface friction alone appeared to produce a change of slightly over 1%. (3) Caution should be used when interpreting data signals from clinometers mounted on the test vehicle. (In the vicinity of the static roll stability limit, small accelerations of the vehicle can significantly influence these signals and may lead to erroneous conclusions.) (4) Very slow table speeds in the vicinity of the stability limit are advisable. Behavior in the immediate vicinity of the static stability limit is dominated by highly non-linear events such as encountering suspension stroke limits and tire liftoff. The quality of vehicle response in the region may depend on the particular non-linearities of the vehicle. This study did not address the relevance of tilt table measurements to "real world" rollover events.

Rollover supply device for plate member

Abstract: PURPOSE:To standardize inclined direction of a plate member for succeeding process to facilitate supply by judging inclined direction of a plate member having trapezoidal sectional form on a rollover arm, selecting need or no need of driving a shutter and rollover angle according to the judgement, and standardizing inclined direction of the plate member and supplying it to the succeeding process. CONSTITUTION:Inclination of a plate member 9 is judged with an inclination judging device 10. In this judging method, a reference bar 10c fitted with approach sensor 10a, 10b on both sides is brought down with a cylinder 10d from over part of the plate member 9, and inclination is judged by ON, OFF condition of the approach sensors 10a, 10b at contact of the reference bar 10 with the plate member. When the approach sensor 10b is ON, 10a is OFF, and it is judged necessary to roll over, a shutter 11 is closed and a rollover arm 7 is rotated. At exceeding 90 degree, the plate member 9 is laid down on the opposite side of the rollover arm 7. At further rotating over the friction angle, the plate member 9 is slidingly moved along the rollover arm 7, transferred to a chute 12, and it is supplied to the succeeding process in rollover condition.

Fatal rollover rates of small utility vehicles and pickups

Abstract: Occupant death rates in rollover crashes for utility vehicles, pickups, and passenger cars for model year 1985-89 vehicles in single-vehicle crashes during 1986-90 were calculated. Small utility vehicles had the highest rollover death rate, followed by small pickups. More than 80% of the single-vehicle crash deaths in small utility vehicles involved rollovers. The Ford Bronco II, especially the two-wheel drive version of this utility vehicle, had the highest rollover rate, followed by the four-wheel drive Nissan 720 short bed pickup.

A rollover protection element for motor vehicles

Abstract: A rollover protection means for motor vehicles which can be raised out of a lowered position in one plane into a supporting position and fixed in this supporting position, has a rollover protection element 3, 4 extending approximately in the longitudinal direction of the vehicle arranged on each of the two sides 7, 8 of a vehicle body and, in the lowered position, is sunk in a vehicle side wall. The rollover protection element 3, 4 may be swung into the supporting position about a bearing 12 or may be displaced vertically with its lateral limbs 9 and 10 being parallel to the vehicle side wall 7. A further limb 14 may project from the rollover protection element 3, 4 to prevent buckling in the transverse direction of the vehicle.