What Causes Rear-End Collisions?

Rear-end collisions rank among the most common car accidents in the United States. They can happen at any speed, from two cars tapping in heavy traffic to violent collisions between a speeding car and a stopped one. It will be no surprise to hear that high-speed rear-end collisions frequently result in catastrophic injuries and fatalities. But even low-speed “fender-benders” can leave drivers and passengers badly hurt.

In this blog post, our Orlando car accident lawyers dig deep into the phenomenon of rear-end collisions: what they are, how they happen, and how you can avoid them.

Rear-End Collisions Defined

In the simplest sense, a rear-end crash occurs when the front end of one vehicle collides with the rear end of another car traveling (or pointing) in the same direction. At the moment of impact, the trailing vehicle always travels faster than the leading vehicle. Often, the leading vehicle is stationary.

The laws of physics dictate that, in most cases, the impact of a rear-end collision causes the trailing vehicle to slow down. In contrast, it causes the leading vehicle to speed up (when there is a huge disparity between the mass and/or velocity of the vehicles, such as in a collision between a speeding cement truck and a stopped subcompact car, the acceleration or deceleration may be minimal for one of the vehicles).

For occupants of the leading vehicle, the sudden, unexpected acceleration causes many of the injuries we typically associate with rear-end collisions (discussed below). But make no mistake, the occupants of both vehicles in a rear-end collision risk suffering severe, even fatal, injuries.

Rear-End Collision Statistics

How common are rear-end collisions? Very common. According to the National Highway Transportation Safety Administration (NHTSA), rear-end collisions consistently account for roughly one-third (33 percent) of all reported two-vehicle accidents in the United States annually. Over the past several years, that has meant there are over two million reported rear-end collisions on American roads annually, according to the NHTSA.

Or, to put it even more starkly, on average, more than three rear-end collisions per minute every year. The most recent Crash Facts report from the Florida Department of Highway Safety and Motor Vehicles does not include rear-end collisions as a specific classification in its annual crash data. These accidents are probably as common in the Sunshine State as anywhere else.

What is the result of all of these accidents? According to the NHTSA data, more than 2,000 rear-end collisions cause fatalities and more than half a million injuries yearly. By any measure, rear-end collisions constitute a severe public health hazard on American roads.

Contributors to Rear-End Collisions

So, what causes rear-end collisions? In the 2000s, the NHTSA set out to answer that question. The agency published two reports, one analyzing factors in rear-end collisions that more effective rear-signaling systems (i.e., better brake lights) can address and the other analyzing the characteristics of drivers in rear-end collisions. Here are some highlights of what they found.

Driver Distraction Plays an Overwhelmingly Significant Role

According to one study, approximately 87 percent of rear-end crashes in which the driver struck the lead vehicle included some form or degree of driver distraction. Distraction makes it more likely drivers will fail to react in time to a vehicle in front of them. The study found that drivers who glanced away from the forward road when a front vehicle began braking had substantially longer brake-reaction times than drivers whose visual focus was on the forward road.

Keeping in mind that the data comes from pre-2007 research before smartphones took over our lives, the study also found that the types of distractions most correlated to rear-end crashes (as compared to near-crashes or less acute incidents) were dining and daydreaming.

At least back then, cell phone use had a strong association with near misses but less with actual crashes. But there is reason to think that in the years since, with the advent of smartphones, that screen use may play an even greater role today as a distraction that causes rear-end collisions than it did back in 2007.

However, the Insurance Institute for Highway Safety observed that reliable data on the correlation between smartphone use and accident causation is difficult to find, partially because cell phone use in accidents likely goes significantly underreported.

Whatever the precise mechanisms that distract us behind the wheel, however, one thing is certain: Taking your eyes off of the road, for whatever reason, vastly increases your risk of getting into a rear-end collision. It likely remains the biggest contributor to these accidents.

Speed Is, Surprisingly, Less of a Factor Than You Might Think

Another intriguing and slightly counterintuitive data point noted in the NHTSA study was that rear-end collisions tended to occur at lower speeds. Relatedly, roughly two-thirds of rear-end crashes observed in the study happened at traffic junctions (intersections, etc.) while the trailing vehicle decelerated and the lead vehicle stopped.

What do these statistics tell us? First, they reflect that trailing drivers often try to avoid rear-end collisions by braking. That’s no surprise. It’s rare, although not unheard of, for a trailing vehicle to slam into the rear of another at high speed without attempting to slow down (or without the time to do so). The other is that many rear-end collisions happen in heavy traffic conditions or in situations where the driver of the trailing vehicle ought to expect the lead vehicle to slow or stop, but for one reason or another, it doesn’t.

This may explain why people tend to think of rear-end collisions as relatively minor; they associate the speed of an accident with its severity. That makes intuitive sense, but as we discuss below, it obscures the fact that even at low speeds, rear-end collisions can cause debilitating injuries.

Driver Age and Sex Play a Role, Too

Researchers looked specifically at whether the age and sex of drivers had any correlation to their role in rear-end collisions. It found that overall, younger drivers, and particularly younger male drivers, were more likely to be the drivers in the trailing car than the leading car. In the general population, older drivers are in fewer accidents than younger drivers, at least until they reach advanced ages.

Rear-End Collision Injuries

For the driver and passenger of the trailing car in a rear-end collision, the potential range of injuries does not differ substantially from the injuries they can sustain in almost any other accident. If they wear their seat belts and have front-impact airbags, most occupants of these vehicles can hope to avoid life-threatening injuries (albeit not always) but may sustain broken bones, lacerations, back injury, and head trauma.

In contrast, occupants of the leading car in a rear-end collision face significant dangers that are somewhat particular to this kind of accident. When the impact occurs, the lead vehicle accelerates violently and unexpectedly. The safety systems that might protect these passengers in a frontal collision do not necessarily have the same effectiveness in this scenario. As their bodies suddenly accelerate forward, then decelerate as their vehicle comes to a rest, occupants of the lead car endure unnatural, injury-causing forces.

Whiplash

One of the most common and misunderstood injuries in rear-end collisions is whiplash. An unfortunate stereotype accompanies this injury that sometimes leads people to think victims are faking it. Nothing can be further from the truth.

The whip that causes a whiplash injury is the whipping motion of a person’s spinal column. When the car they’re riding in suddenly accelerates, the force of that acceleration pushes passengers’ torsos forward. Their backs arch for a split second as their head lags behind the rest of their body mass. In this instant, the force of the collision loads their spinal column the vertebrae and discs giving it an S shape as the force of the impact moves upward the way a bend in a bullwhip does from handle to tip.

And like the tip of a whip that makes a snap when that bend travels the length of the whip, the head snaps back and then forward. In this motion, the soft tissue that supports the neck including muscles and tendons endures enormous strain and inevitably becomes damaged.

Whiplash is a very painful injury. It can resolve on its own, but not always. Some people who sustain a whiplash injury experience secondary symptoms like headaches and chronic neck and back pain for months, or even years.

Back and Spine Injuries

Occupants of the leading car in a rear-end collision also face the risk of back and spine injuries. The same physical forces that cause whiplash can also subject the structure of the spinal column to damage, including burst discs and cracked vertebrae. Those injuries, and the swelling they cause, can also lead to damage to the spinal cord. Spinal cord damage often leads to temporary or permanent paralysis.

A spinal cord injury usually involves damage to the tight bundle of cells and nerves that send and receive signals from the brain to and from the rest of the body. A spinal cord injury can result from a direct injury to the spinal cord or damage to the tissue and bones (vertebrae) surrounding it.

Damage can result in either temporary or permanent changes in sensation, movement, strength, and body functions below the site of an injury. An incomplete spinal cord injury refers to a spinal cord still being able to transmit messages to and from the brain to the rest of the body, while a complete spinal cord injury involves no nerve communication and motor function (voluntary movement) below the site where the trauma occurred.

A spinal cord injury can cause symptoms such as numbness, tingling, or a loss of or changes in sensation in the hands and feet, paralysis, weakness or inability to move any part of the body, pain or pressure in the head, neck, or back, loss of movement, loss of bladder and bowel control, unnatural positions of the spine or head, difficulty breathing, problems walking, and changes in sexual function.

Spinal cord injuries can result in paralysis or the loss of the ability to move a portion or all of your body. Paralysis can affect any part of the body, including the face, hands, one arm or leg (also known as monoplegia), one side of the body (also known as hemiplegia), both legs (also known as paraplegia), or both arms and legs (also known as tetraplegia or quadriplegia).

Other common kinds of back injuries can include sprains and strains, herniated or bulging discs, fractured vertebrae, lumbar spine or lower back injuries, thoracic spine injuries in the mid-back, chest, and rib area, herniated discs, cervical fractures, cervical dislocation, muscle tension, spondylolisthesis, cervical radiculopathy, and spinal stenosis. Back injuries can also involve an increased risk of musculoskeletal disorders, which are injuries or disorders affecting the movement of the body’s musculoskeletal system.

Common musculoskeletal disorders include tendonitis, ligament sprains, tendon and muscle strains, and degenerative disc disease.

Head Trauma/Brain Injury

Common in all car accidents, head trauma and brain injury frequently occur in occupants of the leading car in a rear-end collision. Some of these injuries result from the occupants’ heads striking a hard surface in a car. But the nature of brain injury is such that it can occur even when a person’s head does not take a physical blow but instead experiences a violent force, such as the force exerted in the whipping action associated with whiplash injuries. Brain injuries can cause significant cognitive, motor, and emotional impairment, sometimes permanent.

A traumatic brain injury (TBI) can vary in effects and severity. Some TBIs might have initially mild effects, but lasting symptoms can include headaches, confusion, lightheadedness, dizziness, blurred vision or tired eyes, ringing in the ears, bad taste in the mouth, fatigue or lethargy, behavioral or mood changes, changes in sleep patterns, and trouble with memory, concentration, attention, or thinking. These are still very serious injuries.

Other TBIs can cause a person to show all of the same symptoms listed above but can also involve a headache that gets worse or does not go away, repeated vomiting or nausea, convulsions or seizures, an inability to awaken from sleep, dilation of one or both pupils in the eyes, weakness or numbness in the extremities, slurred speech, loss of coordination, and increased confusion, restlessness, or agitation. About half of severely head-injured TBI patients need surgery to remove or repair hematomas (ruptured blood vessels) or contusions (bruised brain tissue).

Common disabilities associated with a TBI can include problems with cognition (thinking, memory, and reasoning), sensory processing (sight, hearing, touch, taste, and smell), communication (expression and understanding), and behavior or mental health (depression, anxiety, personality changes, aggression, acting out, and social inappropriateness). Some cases can also involve intracranial hematoma (ICH), which involves several types of blood clots in or around the brain.

Different ICHs are classified based on their location in the brain, and the types can range from mild head injuries to very serious and potentially life-threatening injuries:

• Epidural hematoma, which occurs when a blood clot forms underneath the skull but on top of the dura, the covering that surrounds the brain
• Subdural hematoma, which occurs when a blood clot forms underneath the skull and dura, but outside the brain
• Contusions or intracerebral hematoma, which is a bruise to the brain itself causing bleeding and swelling inside of the brain
• Diffuse axonal injuries (DAIs), which are usually caused by shaking of the brain back and forth.

Fractures and Broken Bones

Occupants of motor vehicles involved in rear-end wrecks can suffer broken bones or multiple-fracture injuries. Certain fractures do not require much time to heal, but other fractures may require surgeries or lead to long-term disabilities.

Fractures are bone breaks resulting from a force that exceeds the strength of the osseous tissue in the bone. Many fractures resulting from excessive external forces can be traumatic fractures.

Serious fractures may require reconstructive surgery, and the insertion of pins, plates, and screws that also require longer hospital stays, rehabilitation, and additional surgeries. Fractures may range in severity from minor inconveniences requiring very little medical intervention to severe and life-threatening injuries that can take months to years for a person to reach complete recovery.

Bone fractures generally include simple fractures and compound fractures. Simple fractures or closed fractures are broken bones remaining within the body that do not penetrate the skin.

Compound fractures or open fractures are broken bones that penetrate through the skin and can expose the bone and deep tissues to the exterior environment. Compound fractures are much more serious than simple fractures because they can involve complications with deep infections caused by open wounds.

Simple and compound fractures also involve other specific types of fractures, such as:

• Comminuted fractures, involving bones broken in at least two places; transverse fractures happen when a bone breaks perpendicular to its length, meaning a fracture pattern is a straight line running in the opposite direction of the bone;
• Oblique fractures, involving bones breaking at angles
• Spiral fractures, when bones are broken with a twisting motion, creating a fracture line wrapping around the bone and looking like a corkscrew
• Avulsion fractures, involving small pieces of bones tearing off from the main bones because of extreme force to ligaments or tendons.

Rear-end crashes can cause people to suffer more than just one broken bone, and fractures can prevent them from returning to work for months or even years. Severe fractures can also involve a recovery period that may be a very long and painful process requiring physical therapy, rehabilitation, and additional surgeries.

Internal Injuries

An internal injury is incredibly dangerous because failure to receive immediate treatment can cause serious complications or even death. Common internal injuries may include brain bleeds, broken ribs, pneumothorax involving a rib puncturing a lung, abdominal aorta aneurysms in which the stomach is compressed during an accident and causes a rupture of the abdominal aorta, internal organ injuries, ruptured spleens, and internal bleeding.

Fatalities

Though rear-end collisions result in fewer fatalities than many other types of accidents, they can pose a serious risk to passengers in the rear-most seats in the leading car. The research found that about 75 percent of all fatalities in rear-end collisions resulted from the collapse of the compartment of the leading vehicle. Occupants seated in the rear-most seats of these vehicles face a high risk of crushing or blunt force trauma when the passenger compartment collapses around them.

Avoiding Rear-End Collisions

Sometimes an accident finds you, despite your best efforts. But as a driver, you can avoid falling victim to a rear-end collision both as the trailing driver and the driver of a leading vehicle.

These include:

• Eliminating distractions. As the research above reflects, avoiding distraction is the single most significant step you can take to keep yourself from being the trailing driver in a rear-end collision. Don’t text and drive, don’t eat and drive – don’t do anything but drive and drive.
• Not tailgating. Following other vehicles too closely reduces a driver’s “safety cushion” to react to sudden changes in speed by leading cars. Keeping at least a two-car-length separation substantially reduces the likelihood of a rear-end collision.
• Staying away from aggressive drivers. You gain nothing by retaliating against an aggressive driver. If someone is riding your tail, move over and let him pass. Refusing to move over or, worse, stomping on your brakes to scare him only invites a rear-end collision in which you take the brunt of the impact.
• Exercise caution on slick road surfaces. Every driver must drive at a safe speed for the conditions. When roads are wet and slick, safe speed means safe distance. Reducing your speed to give yourself some extra stopping distance, and staying alert to anyone following you too closely in wet conditions, can help to keep you safe.
• Pick a car with driver assistance features if you can afford them. Collision warning systems and automatic braking systems hold the promise of reducing rear-end collisions. If you can afford a car with those features, they’re likely worth the money.

If you have questions about rear-end collisions or have sustained injuries in a car accident of any kind, contact an experienced car accident attorney today.