@lyg-boy 2017-08-03 14:24:40
1，How do a vehicle’s size and weight affect safety?
All other things being equal, occupants in a bigger, heavier vehicle are better protected than those in a smaller, lighter vehicle. Both size and weight affect the forces people inside a vehicle experience during a crash. The magnitude of those forces is directly related to the risk of injury.
In the case of size, the longer distance from the front of the vehicle to the occupant compartment gives a bigger vehicle an advantage in frontal crashes, which account for half of passenger vehicle occupant deaths. The longer that distance, the bigger the crush zone, and the lower the forces on the occupants.
Weight comes into play in a collision involving two vehicles. The bigger vehicle will push the lighter one backward during the impact. As a result, there will be less force on the occupants of the heavier vehicle and more on the people in the lighter vehicle. Heavier vehicles also fare better in some single-vehicle crashes because they are more likely to move, bend or deform objects they hit.
IIHS demonstrated the role of size and weight in a series of crash tests in 2009 in which a microcar and two minicars were each crashed into a midsize car from the same manufacturer. The Smart Fortwo, Honda Fit and Toyota Yaris all had good ratings in the Institute’s moderate overlap frontal test, but all three performed poorly in the crashes with midsize cars.
IIHS在2009年做了一系列实验，让The Smart Fortwo, Honda Fit and Toyota Yaris同他们生产商所生产的中级车对撞。虽然他们都在前部碰撞实验中获得了good，但是他们在同中级车的碰撞中完全处于下风。
2 Are people less likely to be killed or injured in a bigger, heavier vehicle?
Yes. Driver death rates calculated by IIHS illustrate the real-world advantages of bigger, heavier vehicles. For example, as a group, in 2012 very large cars 1-3 years old had 20 deaths per million registered vehicles, while minicars had 77. Of the 26 vehicles with the lowest driver death rates from the 2005-08 model years during 2006-09, all but three were midsize or larger. More than half of those with the highest rates were small vehicles or minicars. 2
Improvements in crash protection have made vehicles of all sizes safer, but, as illustrated in the figure below, an advantage persists for bigger vehicles, as measured by shadow, or length times width. Size and weight are highly correlated, so the figure would look similar if weight were used instead.
是的。大的重的车的驾驶员更有优势，死亡几率更小。举例，在分组中，2012年车龄在1-3年的very large car中，每百万死20个人,minicar中，这个数字上升到77.在05-08那边和06-09年的记录中，死亡率最低的26辆车只有3两不是中型或大型车。死亡率最高的车型中超过一半是小车。
3 What’s more important, size or weight?
It’s difficult to separate the effect of weight from the effect of size in the real world. However, a recent HLDI analysis did this to some extent by comparing hybrid vehicles with their conventional, nonhybrid twins. 3 These pairs are identical except for the battery packs that give the hybrids extra mass. The analysis of insurance claims found that the odds of being injured in a crash are 25 percent lower for people in hybrids than for people in the nonhybrid versions of the same vehicles. While other factors, including how, when and by whom hybrids are driven also may contribute to their advantage, HLDI concluded that the extra weight is likely a key factor.
Size also confers its own advantages, independent of mass. For example, among 2005-08 models, SUVs weighing 3,001-3,500 pounds had 39 driver deaths per million registered vehicles, compared with 51 for cars in the same weight range. 2
The advantage for SUVs may be connected to their taller profile. For one thing, the taller a vehicle is, the less likely it is to underride another vehicle in a crash. In addition, crash testing suggests that sitting higher makes occupants less likely to have head and chest injuries when their vehicles are struck in the side by shorter vehicles because the point of impact is lower.
This SUV advantage is a relatively new phenomenon. In the past, these vehicles had some of the highest death rates because they were prone to rollover crashes, and that tendency outweighed any advantage from their bigger size. That’s no longer a factor because of less top-heavy designs and the increasing prevalence of electronic stability control, which prevents rollovers and is now required on all new vehicles.
尺寸也有它的优势，例如 05-08年代的车型中 ，3000-3500磅重的SUV 每百万死39个，而轿车死51.