Showing papers on "Rollover published in 1990"

Feasibility study of a rollover warning device for heavy trucks

Abstract: This report assesses the technical feasibility of a device that would warn the operators of heavy trucks of incipient rollover. The technical factors associated with wheel liftoff and vehicle rollover are explored. A measure known as the lateral load transfer ratio (LTR) is identified as the best parameter for predicting incipient rollover. The cost of a rollover warning device (RWD) based on LTR measurement is assessed and compared with the financial costs and rates of injuries and fatalities identified through a survey of heavy truck accidents in western Canada. On the basis of the cost comparison, it is concluded that a stand-alone, LTR-based RWD is not feasible. However, it appears that the integration of an LTR-based device with an existing on-board weigh scale system would be cost-effective because of the substantial commonality of the two systems. An outline of further research and development is given to establish the performance of rollover warning devices. Initially, this work would involve the instrumentation of a test vehicle and the performance of tilt- table tests. Subsequent on-road testing at a test facility would be conducted to evaluate further the performance of the devices and to define better specific rollover prediction criteria.

Motor vehicle having a rollover bar

Abstract: A convertible motor vehicle is provided with two rollover bars which can be swivelled out of a lowered inoperative position into an upwardly directed supporting position and back around a swivel axis fixed at the vehicle and extending essentially in the longitudinal direction of the vehicle. The rollover protection system can be integrated into conventional vehicle concepts in a particularly space-saving and advantageous manner and reduces the risk of injury in the case of a fast, sensor-controlling swinging-up of the rollover bars.

Truck characteristics for use in highway design and operation. volume i: research report. final report

Abstract: Highway geometric design and traffic operations are based in part on consideration of vehicle characteristics. However, many of the current highway design and operational criteria are based on passenger car characteristics, even though truck characteristics may be more critical. This report reviews existing data for the truck characteristics that need to be considered in highway design, including truck dimensions, braking distance, driver eye height, acceleration capabilities, speed-maintenance capabilities on grades, turning radius and offtracking characteristics, suspension characteristics, and rollover threshold. The report also includes these truck characteristics. The highway design and operational criteria evaluated include sight distances, vertical curve length, intersection design, critical length of grade, lane width, horizontal curve design, vehicle change intervals at traffic signals, sign placement, and highway capacity. An assessment has been made of the need to change the current highway design and operational criteria to accommodate trucks. The cost effectiveness of proposed changes in design and operational criteria has been evaluated. This volume, Volume I, of the report presents the main findings of the study including recommended changes in highway geometric design and operational criteria to accommodate trucks. Volume II of the report contains appendixes documenting the detailed data collection and analysis activities.

Analysis of the relationship between vehicle rollover stability and rollover risk using the nhtsa cardfile accident database

Abstract: Statistical confirmation of the important relationship between vehicle rollover stability, as defined by the ratio of half track width to center of gravity height, and rollover rate, as defined by the ratio of rollovers per single vehicle accident (RO/SVA) expressed as a percent, has been established using data extracted from the automated police accident reports of three states. A consistent and robust relationship between this measure of stability and single vehicle crashes involving rollover was found by means of linear regression analysis techniques. The relationship of this stability factor with the rollover per registered vehicle rate further substantiates the tendency for this type of crash to be associated with vehicles possessing a low rollover stability index.

Truck characteristics for use in highway design and operation; volumes 1 and 2

Abstract: Highway geometric design and traffic operations are based in part on consideration of vehicle characteristics. However, many of the current highway design and operational criteria are based on passenger car characteristics, even though truck characteristics may be more critical. This report reviews existing data for the truck characteristics that need to be considered in highway design, including truck dimensions, braking distance, driver eye height, acceleration capabilities, speed-maintenance capabilities on grades, turning radius and offtracking characteristics, suspension characteristics, and rollover threshold. The report also includes these truck characteristics. The highway design and operational criteria evaluated include sight distances, vertical curve length, intersection design, critical length of grade, lane width, horizontal curve design, vehicle change intervals at traffic signals, sign placement, and highway capacity. An assessment has been made of the need to change the current highway design and operational criteria to accommodate trucks. The cost effectiveness of proposed changes in design and operational criteria has been evaluated (A).

Rollover simulation and crashworthiness analysis of trucks

Abstract: This paper presents a computer-based technique for the dynamic analysis of multibody systems undergoing large motion and structural deformations. As a specific example, this formulation is applied to the rollover simulation of a truck (multibody system) to determine the deformation of its safety rollbar cage (structure). The cab or safety rollbar cage is modeled by the finite element method. The model may contain beam, plate, or other types of finite elements. The material property of the structure is assumed to be linear for small structural deformations. However, in severe rollover or crash situations the deformation is no longer elastic, therefore, elasto-plastic material characteristics must be considered

Methodology for estimating safe operating speeds for heavy trucks and combination vehicles on interchange ramps

Abstract: A number of research studies have shown the significance of considering truck and combination vehicle performance in the geometric design of interchange ramps. The greater potential these vehicles have for offtracking and loss of control as well as rollover plays an important role in determining the safe speed of a ramp. The analysis procedure described provides highway engineers with a method, first, to determine the critical speed of a ramp for such heavy vehicles. The PHASE-4 computer model is used to simulate the dynamic behavior of the vehicle for a specified ramp geometry. The complete procedure is computerized with a user friendly interface for specifying ramp parameters and built-in data sets of vehicle parameters. Then, a method to convert the critical speed to a safe operating speed for the ramp is presented. Input parameters and results for an example ramp consisting of one simple horizontal curve are included as a demonstration. The ramp is analyzed with two types of combination vehicles. The method for estimating the safe operating speed is then demonstrated by converting the critical speeds to safe operating speeds.

Motor vehicle rollover bar driving system

Abstract: Rollover protection for occupants of a convertible motor vehicle is formed by two rollover bars which are disposed on a base plate and can be swivelled around swivel axes extending approximately in the longitudinal direction of the vehicle, approximately in the plane of the base plate. At the base plate which is installed largely in the transverse direction of the vehicle and approximately perpendicularly to the longitudinal direction, control elements for the swivelling of the rollover bars, as well as the triggering mechanisms and the locking devices for the extended rollover bars, are disposed. The rollover protection system can be pre-assembled easily, and the adjustability of all driving and locking elements is good. As a result of the flat construction, the system requires little installation space and permits a favorable moving direction of the rollover bars during the extending operation.

A Model of Vehicle Rollover Due to Side Impact Collision

Abstract: Cars involved in side impact collisons have been known to roll over as a direct consequence of the side impact. A simple mathematical model is derived for collision rollover in central and eccentric side impacts. It is shown that the minimum impact velocity of the bullet vehicle or object necessary to cause rollover is dependent on the mass ratio of the struck vehicle to that of the bullet vehicle/object, the impact height, the tyre-road friction and on the eccentricity of the impact. The rollover velocity decreases as friction is increased. Consequently this form of rollover will, in general, most often occur on dry roads and at moderate to high impact velocities. The model is compared with data from staged motorcycle/car impacts and with two road accidents which resulted in rollover.

Truck characteristics for use in highway design and operation. volume ii: appendixes. final report

Abstract: Highway geometric design and traffic operations are based in part on consideration of vehicle characteristics. However, many of the current highway design and operational criteria are based on passenger car characteristics, even though truck characteristics may be more critical. This report reviews existing data for the truck characteristics that need to be considered in highway design, including truck dimensions, braking distance, driver eye height, acceleration capabilities, speed-maintenance capabilities on grades, turning radius and offtracking characteristics, suspension characteristics, and rollover threshold. The report also includes these truck characteristics. The highway design and operational criteria evaluated include sight distances, vertical curve length, intersection design, critical length of grade, lane width, horizontal curve design, vehicle change intervals at traffic signals, sign placement, and highway capacity. An assessment has been made of the need to change the current highway design and operational criteria to accommodate trucks. The cost effectiveness of proposed changes in design and operational criteria has been evaluated. This volume, Volume II, of the report contains appendixes documenting the detailed data collection and analysis activities. Volume I of the report presents the main findings of the study including recommended changes in highway geometric design and operational criteria to accommodate trucks.

Rollover, braking, and dynamic stability-modified suspension vehicles. final report. volume 1. technical report

Abstract: A study was performed to investigate the dynamic response properties of modified suspension pickup trucks and utility vehicles in particular open loop steering and braking maneuvers Three example vehicles were tested, a 1985 Toyota pickup, a 1986 Chevrolet K-20 pickup, and a 1986 Chevrolet S-10 Blazer; in both their OE configurations and with extensive suspension, chassis, and tire modifications using aftermarket components These modifications tended to increase the cg height, widen the track, decrease braking gain, increase suspension compliance, and possibly lead to greater loads on suspension components Outriggers were used to prevent rollover, and an automatic vehicle controller was used to input large, repeatable and rapid open loop maneuvers Each vehicle configuration was tested in 5 maneuvers, including straight line braking, trapezoidal steering, braking in a turn, steady state turning, and sinusoidal steering Full scale test results are presented to show the effect of vehicle modifications on sublimit and limit performance in these maneuvers

A model of vehicle rollover due to side impact collision . proceedings of the institution of mechanical engineers

Abstract: Cars involved in side impact collisions have been known to roll over as a direct consequence of the side impact. A simple mathematical model is derived for collision rollover in central and eccentric side impacts. It is shown that the minimum impact velocity of the bullet vehicle or object necessary to cause rollover is dependent on the mass ratio of the struck vehicle to that of the bullet vehicle/object, the impact height, the tyre-road friction and on the eccentricity of the impact. The rollover velocity decreases as friction is increased. Consequently this form of rollover will, in general, most often occur on dry roads and at moderate to high impact velocities. The model is compared with data from staged motorcycle/car impacts and with two road accidents which resulted in rollover. (Author/TRRL)

Rollover collisions: a continuing problem for occupant mortality

Abstract: The authors have been conducting a statistically-based study of injury-producing collisions involving passenger cars in southwestern Ontario for the past five years. Currenlty, over 500 cases have been documented as part of this study. Vehicle rollover is found to be involved in 8% of the cases and yet this crash mode produces 16% of fatal collisions. Although Ontario has had mandatory seat-belt legislation since 1976, 90% of the occupants fatally injured in rollover collisions were unbelted. Many of these fatalities were a direct result of the unrestrained occupants being partially or completely ejected from the vehicle, a situation which would be largely mitigated through the use of seat belts. The problem of rollover collisions is discussed in terms of these and other factors. Recommendations for suitable countermeasures are put forward in the light of the study's findings. (A)

Testing and analysis of vehicle rollover behavior. in: accident reconstruction: human, vehicle and environmental factors. sae international congress & exposition, detroit michigan, 1990

Abstract: Neither the experimental nor analytical techniques currently used to study vehicle rollover accidents accurately represent most actual rollovers. Until recently, crash tests to study rollovers have used either snubbed dollies or guided ramps to cause rollovers. Real world rollovers, however, are caused by a variety of mechanisms, including impacting curbs or obstacles, sliding through soil or sod, and dropping off embankments. Analytical methods proposed to model rollover events represent idealized curb trip situations and provide unrealistically low estimates for the lateral speeds needed to cause rollovers. This paper presents the results of a continuing investigation into the mechanics of real world vehicle rollovers. Rollover tests with vehicles tripped by a curb, sliding in soil, and thrown from a dolly are presented. The mechanics of the different trip modes is discussed and a simple analytical model to represent the trip mode behavior presented.

A model of vehicle rollover due to side impact collision

Abstract: Cars involved in side impact collisons have been known to roll over as a direct consequence of the side impact. A simple mathematical model is derived for collision rollover in central and eccentric side impacts. It is shown that the minimum impact velocity of the bullet vehicle or object necessary to cause rollover is dependent on the mass ratio of the struck vehicle to that of the bullet vehicle/object, the impact height, the tyre-road friction and on the eccentricity of the impact. The rollover velocity decreases as friction is increased. Consequently this form of rollover will, in general, most often occur on dry roads and at moderate to high impact velocities. The model is compared with data from staged motorcycle/car impacts and with two road accidents which resulted in rollover.

Consumer Perception of Light Truck Safety

Abstract: The popularity of light trucks has increased tremendously since their introduction in the 1970's. Also increasing is the accident rate and injury severity of passengers involved in light truck accidents according to literature dating as far back as 1979. There are several federal requirements which apply to passenger cars that are not in effect for light trucks, primarily overhead and side structural protection. Also, the light trucks, especially the four-wheel drive models, have a greater propensity for rollover accidents due to their higher center of gravity. At issue in a products liability case regarding a light truck accident is whether or not the product meets the consumer's reasonable expectations. To determine what the consumer expectations are for the performance and safety of light trucks, a survey was conducted which addressed the issues of how safe the participants felt a truck was in comparison to other motor vehicles and under a variety of driving conditions. In order to determine how advert...

Engineering parameters related to rollover frequency. in: accident reconstruction: human, vehicle and environmental factors. sae international congress & exposition, detroit michigan, 1990

Abstract: Rollover frequency in single vehicle crashes is much higher for pickup trucks and utility vehicles (60-80 percent) than it is for cars (30-50 percent). Vehicle parameters affecting stability (and thus rollover) were examined to determine their contribution to the difference in rollover frequency among passenger cars, pickup trucks and utility vehicles. Logistic regression techniques were used to develop parameter estimates for the risk of rollover in single vehicle fatal crashes. Fatal Accident Reporting System (FARS) data for 1981-1987 were used together with engineering data for 11 models of pickup, 16 models of utility vehicle and 11 models of passenger car. Separate parameter estimates were derived for the three vehicle types to predict risk of rollover in rural and urban areas. Among vehicle design parameters, track width to center of gravity height was the strongest predictor of vehicle rollover for pickup trucks and utility vehicles; for utility vehicles, wheelbase to track ratio was also significant. For passenger cars, wheelbase was the best predictor of rollover risk. A combined model was run to establish whether a single model could be used to predict rollover risk for all three vehicle types. Wheelbase, track width to center of gravity height and driver age were all significant predictors of rollover risk, but were not sufficient to explain all the variation in rollover risk between light trucks and passenger cars. The models showed that reducing the track width to center of gravity height ratio of trucks to that for passenger cars could reduce rollover frequency by as much as 60 percent.

Rollover, braking, and dynamic stability--modified suspension vehicles, final report. volume ii: appendices a-d

Abstract: A study was performed to investigate the dynamic response properties of modified suspension pickup trucks and utility vehicles in particular open loop steering and braking maneuvers. Three example vehicles were tested, a 1985 Toyota pickup, a 1986 Chevrolet K-20 pickup, and a 1986 Chevrolet S-10 Blazer; in both their OE configurations and with extensive suspension, chassis, and tire modifications using aftermarket components. These modifications tended to increase the cg height, widen the track, decrease braking gain, increase suspension compliance, and possibly lead to greater loads on suspension components. Outriggers were used to prevent rollover, and an automatic vehicle controller was used to input large, repeatable and rapid open loop maneuvers. Each vehicle configuration was tested in 5 maneuvers, including straight line braking, trapezoidal steering, braking in a turn, steady state turning, and sinusoidal steering. Full scale test results are presented to show the effect of vehicle modifications on sublimit and limit performance in these maneuvers.