Optimized Vehicle Front Ends for Better Protection of Pedestrians

26 Apr 2019 Vehicle Technology
The construction and design of vehicles also play a very important role in the road safety of children who are walking or riding bicycles. This is especially true for passenger cars, as they are the objects most frequently involved in accidents. Fortunately, a lot has been done in this respect in recent decades. Optimizations made by vehicle manufacturers to protect pedestrians were aimed primarily at making any possible contact areas as smooth and soft as possible.
A quick look back: Until the 1970s, bumpers lived up to their name. Initially, they were made of nickel- plated or chromed steel and later of plastic. In contrast, today's bumpers consist of a large plastic cover that is filled with either energy-absorbing foams or deformation elements made of sheet metal or plastic structures. Also, today’s bumpers are integrated into the vehicle design and there is no longer a gap between the bumper and the front grille. This reduces the bending moment in the legs caused by the impact and thus the likelihood of bone fractures as well.
If a pedestrian is literally knocked off his feet by the impact of a vehicle, a sequence of movements will follow, potentially resulting in serious injuries. Depending on the collision speed, body size, and vehicle frontend structure, the pelvis and upper body will bounce off the hood and possibly the windshield. The head will hit the vehicle with great force. In order to reduce the risk of injury resulting from a head impact, some deformation elements have been integrated into hoods of cars and the distance between the hood and engine block has been increased by design. The increased deformation clearance between the hood and the engine block allows the vehicle to absorb more impact energy, reduce head deceleration, and reduce the risk of impact with the rigid engine components installed under the hood. Active hoods, where the hood is raised in a collision with a pedestrian, are also used on some vehicles. Furthermore, the wipers are now hidden under the back area of the hood. A direct impact of the head on the components of a windshield wiper can cause serious injury.
Since 2012, there is also a standard pedestrian airbag that covers the lower windshield area. Depending on the vehicle, body size, type of collision, and speed, these airbags are also beneficial for children. Rigid hood ornaments are banned today in many countries because they pose an increased risk of injury. So today they either bend or are retracted abruptly at the slightest touch.
For many years, frontal protection systems, also called “cow catchers”, were a fad on European roads, especially on SUVs and vans. But due to their massive design, they present a very high risk of injury, especially for children. The “cow catcher” was located especially at the height of the head and upper body of children. Severe to fatal injuries could already be expected from moderate speeds. Furthermore, the cow catchers undid all the measures designed for the front end of the vehicle to protect pedestrians. Therefore, since 2006 vehicles with frontal protection systems have to comply with Directive 2005/66/EC. Since then, the “cow catchers” have de facto disappeared from road traffic in Europe.
The consumer protection organization Euro NCAP explicitly includes the protection of walking children in its vehicle tests. A crash test headform that corresponds to the size of a child's head is used to assess the risk of injury during head impact. So vehicle manufacturers must also make child-critical areas of the vehicle front end safer to achieve a good overall result. Euro NCAP uses impactors corresponding to the body parts of an adult for the area of the thigh, pelvis, and legs. Forms explicitly for children do not exist in these cases – but they too benefit from the design improvements in these areas.
The current Euro NCAP rating forces manufacturers to make significantly greater efforts in pedestrian safety to continue to receive four or five stars for their vehicles. The test for pedestrian emergency braking systems introduced in 2016 was also extended to include cyclists in 2018. In 2018, China NCAP introduced a pedestrian safety evaluation including AEB test. A pedestrian safety rating is also expected as part of the US NCAP in the next few years.

Vehicle all-round visibility remains a big problem

When it comes to vehicle design, one aspect must not be forgotten: all-round visibility from inside the vehicle. And it is not always optimally provided, especially in the popular SUVs and vans. This was the result of a test of 69 vehicles conducted by the Touring Club Switzerland (TCS) in 2017, among other things. It determined how well the near field of the vehicles front and rear ends can be viewed, how well they can park, and which parking assistance systems are standard on board.
The evaluation of the measurements of the TCS showed that the small cars tested offer the best all-round visibility. Station wagons finished second, followed by cars of the compact class, vans, and limousines. SUVs, which usually provide a better view of the traffic in front and to one side because of the raised position of the seats, but are rather unwieldy when it comes to maneuvering and parking, trailed behind. In this respect, small cars have a clear advantage, according to the TCS. Because the distance between the driver and the rear window is shorter, the viewing angle is steeper and obstacles behind the vehicle can be seen earlier when it is reversing. Even station wagons have an advantage with respect to the rear view, because the rear window often slopes steeply.
The TCS results also reflected this evaluation impressively. While you can see the upper edge of a 50-centimeter-high obstacle from a distance of 1.9 meters in the compact smart fortwo when reversing, it would be visible from inside the SUV Ford Edge only from 12.5 meters away. In real life, this obstacle could also be a child playing on a tricycle. The fact that this is not a problem to be underestimated is demonstrated repeatedly by tragic accidents in which children are killed or injured by reversing cars.
For example, NHTSA studies in the US for the years 2007 to 2011 found that approximately 85 of the estimated almost 270 road users killed in accidents involving cars moving in reverse were children under the age of five. The NHTSA estimates that about 40 percent of fatal accidents involving cars moving in reverse do not occur on public roads, but in private driveways and parking lots. To prevent this, since May 2018 all newly registered cars in the USA must have a vehicle backup camera. The European Commission is also considering requirements.