Roadway safety engineering is a complex field that focuses on more than just stopping a vehicle; it focuses on how that vehicle is stopped. One of the most dangerous outcomes of a high-speed collision is when a car becomes airborne or rolls over after striking a roadside barrier.
To combat these specific hazards, engineers rely on advanced safety systems designed to manage kinetic energy and maintain vehicle orientation.
The strategic use of crash cushion attenuators plays a pivotal role in ensuring that out-of-control vehicles remain grounded and stabilized during an impact. Here are five ways these devices prevent the catastrophic results of vaulting and rollovers.
1. Eliminating the Ramp Effect of Barrier Terminals
Historically, the ends of guardrails and concrete barriers were often blunt or buried, which unfortunately created a ramp-like surface for vehicles striking them at specific angles. Modern crash cushion attenuators are designed to eliminate this ramping effect providing a collapsible interface.
Instead of the vehicle front end being lifted off the pavement, the device absorbs the force horizontally. This energy dissipation ensures that the tires remain in contact with the road surface, preventing the upward trajectory that leads to dangerous vaulting.
2. Maintaining a Low Center of Gravity During Impact
Stability during a crash is largely dependent on keeping the center of gravity of a vehicle as low as possible. When a car strikes an unforgiving object, the sudden transfer of energy can cause the chassis to twist or lift.
High-performance crash cushion attenuators are engineered with specific height profiles that align with the bumpers and frames of modern passenger vehicles.
By engaging the vehicle at the correct height, the attenuator prevents the uneven lifting forces that typically trigger a rollover event, especially in top-heavy vehicles like SUVs and trucks.
3. Controlled Deceleration and Kinetic Energy Management
Vaulting often occurs when a vehicle hits a solid object with such force that the remaining energy has nowhere to go but up. The internal components of crash cushion attenuators are designed to deform, shear, or crush in a predictable sequence.
This staged collapse provides a controlled deceleration, bleeding off the speed of the vehicle over several feet rather than several inches.
This gradual reduction in momentum is essential for keeping the vehicle under control and preventing the violent, erratic movements that precede a roll.
4. Lateral Stability and Redirective Capabilities
Not all accidents are head-on; many involve side-angle impacts where a vehicle might skid along a barrier. Redirective crash cushion attenuators are equipped with side panels and internal guidance tracks that catch the vehicle and guide it back toward the roadway at a shallow angle.
By preventing the vehicle from digging into the barrier, these systems minimize the lateral friction that can flip a car over. This lateral stability is a fundamental requirement for maintaining safety in narrow highway medians.
5. Prevention of Secondary Collisions
A vehicle that vaults or rolls is no longer just a danger to its occupants; it becomes a projectile that can land in oncoming traffic or strike workers in a construction zone.
Because the primary function of these safety devices is to capture or redirect the vehicle safely, they significantly reduce the likelihood of secondary accidents.
Keeping the vehicle upright and contained within its own travel lane protects other motorists and allows emergency responders to access the scene more safely and efficiently.