In May 2013 the

World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level of h ...

(WHO) reported that more than 270,000

pedestrian A pedestrian is a person traveling on foot, whether walking or running. In modern times, the term usually refers to someone walking on a road or pavement, but this was not the case historically. The meaning of pedestrian is displayed with ...

s lose their lives on the world’s roads each year, accounting for 22% of the total 1.24 million road traffic deaths. Despite the magnitude of the problem, most attempts at reducing pedestrian deaths had historically focused solely on education and traffic regulation. Since the 1970s, crash engineers have begun to use design principles that have proved successful in protecting car occupants to develop vehicle design concepts that reduce the likelihood of injuries to pedestrians in the event of a car-pedestrian crash. These involve redesigning the

bumper Bumper or Bumpers may refer to: People * Betty Bumpers (1925-2018), American activist, First Lady of Arkansas, wife of Dale Bumpers * Dale Bumpers (1925–2016), American politician, governor of Arkansas and senator * Bumper Robinson (born 197 ...

, hood (bonnet), and the

windshield The windshield (North American English) or windscreen (Commonwealth English) of an aircraft, car, bus, motorbike, truck, train, boat or streetcar is the front window, which provides visibility while protecting occupants from the elements. Mo ...

and

pillar A column or pillar in architecture and structural engineering is a structural element that transmits, through compression, the weight of the structure above to other structural elements below. In other words, a column is a compression member. ...

to be energy absorbing (softer) without compromising the structural integrity of the car. With the advent of ADAS (Automated Advanced Driver Assist Systems) since 2005, new pedestrian detection and crash avoidance and mitigation systems offer improvements through active rather than passive protection systems. For example,

omniview technology Omniview technology (also known as surround view or bird view) is a vehicle parking assistant technology that first was introduced in 2007 as the "Around View Monitor" option for the Nissan Elgrand and Infiniti EX. It is designed to assist drivers ...

allows a driver to see what is around the vehicle before moving. Rossi lhf safdao Z1

Anatomy of a pedestrian crash

Many pedestrian crashes involve a forward moving car (as opposed to buses and other vehicles with a vertical hood/bonnet). In such a crash, a standing or walking pedestrian is struck and accelerated to the speed of the car and then continues forward as the car brakes to a halt. The pedestrian is impacted twice, first by the car and then by the ground, but most of the fatal injuries occur due to interaction with the car. Vehicle designers usually focus on understanding the car-pedestrian interaction, which is characterized by the following sequence of events: the vehicle bumper first contacts the

lower limb The human leg, in the general word sense, is the entire lower limb of the human body, including the foot, thigh or sometimes even the hip or gluteal region. However, the definition in human anatomy refers only to the section of the lower limb ext ...

s of the pedestrian, the leading edge of the hood hits the upper

thigh In human anatomy, the thigh is the area between the hip (pelvis) and the knee. Anatomically, it is part of the lower limb. The single bone in the thigh is called the femur. This bone is very thick and strong (due to the high proportion of bone ...

pelvis The pelvis (plural pelves or pelvises) is the lower part of the trunk, between the abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also called bony pelvis, or pelvic skeleton). The ...

, and the

head A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple animals may ...

and upper

torso The torso or trunk is an anatomical term for the central part, or the core, of the body of many animals (including humans), from which the head, neck, limbs, tail and other appendages extend. The tetrapod torso — including that of a human � ...

are struck by the top surface of the hood and/or windshield.

Reducing pedestrian injuries

Most pedestrian deaths occur due to the

traumatic brain injury A traumatic brain injury (TBI), also known as an intracranial injury, is an injury to the brain caused by an external force. TBI can be classified based on severity (ranging from mild traumatic brain injury TBI/concussionto severe traumatic b ...

resulting from the hard impact of the head against the stiff hood or windshield. In addition, although usually non-fatal, injuries to the lower limb (usually to the knee joint and long bones) are the most common cause of disabilities. A Frontal Protection System (FPS) then can be device fitted to the front end of a vehicle to protect both pedestrians and cyclists in the event of a front-end collision. Car design has been shown to have a large impact on the scope and severity of pedestrian injury in car crashes. PedInjuryPatterns

Volvo The Volvo Group ( sv, Volvokoncernen; legally Aktiebolaget Volvo, shortened to AB Volvo, stylized as VOLVO) is a Swedish multinational manufacturing corporation headquartered in Gothenburg. While its core activity is the production, distributio ...

has created a pedestrian and cycle recognition ADAS with automatic braking designed to reduce pedestrian collisions. With pedestrian injuries and fatalities increasing dramatically in the US in 2017, perhaps because of increasingly distracted driving with entertainment and communication systems in cars, pedestrian safety driver support systems may become widespread.

Protecting the head

The hood of most vehicles is usually fabricated from sheet metal, which is a compliant energy absorbing structure which poses a comparatively small threat. Most serious head injuries occur when there is insufficient clearance between the hood and the stiff underlying engine components. A gap of approximately 10 cm is usually enough to allow the pedestrian’s head to have a controlled

deceleration In mechanics, acceleration is the rate of change of the velocity of an object with respect to time. Accelerations are vector quantities (in that they have magnitude and direction). The orientation of an object's acceleration is given by t ...

and a significantly reduced risk of death. Creating room under the hood is not always easy because usually there are other design constraints, such as aerodynamics and styling. In some regions of the hood it can be impossible. These include along the edges on which the hood is mounted and the cowl, where the hood meets the windshield. Engineers have attempted to overcome this problem by using deformable mounts, and by developing more ambitious solutions such as airbags that are activated during the crash and cover the stiff regions of the hood. Some models, like the

Citroën C6 The Citroën C6 is an executive car produced by the French car maker Citroën since 2005. The Citroën C6 was inspired by the Citroën C6 Lignage concept car with a fastback saloon like styling. Inspired by the Citroën C6 Lignage prototype, ...

and

Jaguar XK The Jaguar XK is a two-door 2+2 grand tourer manufactured and marketed by British automobile manufacturer Jaguar Cars from 1996–2014 in hatchback coupé and convertible bodystyles, across two generations. The XK was introduced at the Ge ...

feature a novel pop-up

bonnet A Bonnet is a variety of headgear, hat or cap Specific types of headgear referred to as "bonnets" may include Scottish * Blue bonnet, a distinctive woollen cap worn by men in Scotland from the 15th-18th centuries And its derivations: ** Fea ...

design, which adds 6.5 cm (2.5", C6) extra clearance over the engine block if the bumper senses a hit. In 2012 and 2015, the Volvo V40 and the

Land Rover Discovery Sport The Land Rover Discovery Sport (internal code L550) is a compact luxury crossover SUV produced by British automotive company Jaguar Land Rover since 2014, under their Land Rover marque, and since 2017 their best-selling model. Introduced in ...

have an under-the hood airbag designed to operate if the hood senses a hit. The airbag is also designed to cover the windshield pillars to help protect the pedestrian's head.

Protecting the limbs

Most limb injuries occur due to a direct blow from the bumper and the leading edge of the hood. This leads to contact fractures of the

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with ...

and the

tibia The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it connects ...

fibula The fibula or calf bone is a leg bone on the lateral side of the tibia, to which it is connected above and below. It is the smaller of the two bones and, in proportion to its length, the most slender of all the long bones. Its upper extremity is ...

and damage to the

knee In humans and other primates, the knee joins the thigh with the leg and consists of two joints: one between the femur and tibia (tibiofemoral joint), and one between the femur and patella (patellofemoral joint). It is the largest joint in the hu ...

ligaments due to bending of the joint. Thus, attempts at reducing these injuries involve reducing the peak contact forces by making the bumper softer and increasing the contact area and by limiting the amount of knee bending by modifying the geometry of the front end of the car.

Computer simulations Computer simulation is the process of mathematical modelling, performed on a computer, which is designed to predict the behaviour of, or the outcome of, a real-world or physical system. The reliability of some mathematical models can be dete ...

and experiments with

cadaver A cadaver or corpse is a dead human body that is used by medical students, physicians and other scientists to study anatomy, identify disease sites, determine causes of death, and provide tissue to repair a defect in a living human being. Stud ...

s show that when cars have lower bumpers, the thigh and leg rotate together causing the knee to bend less and thus reducing the likelihood of

ligament A ligament is the fibrous connective tissue that connects bones to other bones. It is also known as ''articular ligament'', ''articular larua'', ''fibrous ligament'', or ''true ligament''. Other ligaments in the body include the: * Peritoneal li ...

injuries. Deeper bumper profiles and structures under the bumper (such as the air dam) can also assist in limiting the rotation of the leg.

Trams

An early example can be found on

tram A tram (called a streetcar or trolley in North America) is a rail vehicle that travels on tramway tracks on public urban streets; some include segments on segregated right-of-way. The tramlines or networks operated as public transport are ...

s in the form of a lifeguard which prevents pedestrians from being caught between the wheels of the leading

bogie A bogie ( ) (in some senses called a truck in North American English) is a chassis or framework that carries a wheelset, attached to a vehicle—a modular subassembly of wheels and axles. Bogies take various forms in various modes of transp ...

should they be hit. When a pedestrian hit the lifeguard a scoop/grille would be automatically lowered in front of the vehicle. This protects the tram against derailment as well as reducing the likelihood of the pedestrian being killed. Lifeguards were compulsory on UK trams from early in the 1900s.

References

# # # # # # SAE Paper No. 831623

External links

Ciaran Simms talks about "Pedestrian crash safety: a triumph of design in bioengineering" at Ignite Dublin #1
{{DEFAULTSORT:Pedestrian Safety Through Vehicle Design Road transport Vehicle safety technologies Pedestrian safety