Mustang Parts
   Carrying Saleen wheels and Bullitt wheels.

Tuesday, March 29, 2005

Ford's Roof Strength Red Face

Today there is a Detroit News article with some very embarrassing news for Ford.

Ford just lost a $10 million lawsuit brought by a man whose wife was killed in a Explorer roll-over accident. The man claimed that the Explorer's roof crush strength was insufficient to protect his wife, and Ford knew that the design was weak.

The man's lawyers subpoenaed Ford documents which showed that some Ford engineers thought that the roof strength of the Explorer (circa 1995MY) had fallen too far below the company's own standard of a strength-to-weight ratio of 1.875. Ford decided against upgrading the roof strength, most likely to save money. Strike one.

However, Volvo (later purchased by Ford) had much more stringent roof standards. For the new XC90 SUV, Volvo engineered a very strong roof, and Ford has been advertising this as a selling point on how safe the XC90 is. Strike two.

Finally, Ford (along with GM and Chrysler) have fought proposals to increase the Federal standard for roof strength, FMVSS 216. Strike three.

In Ford's defense, injuries due to roll-over roof crush are a complicated problem, and there is no guarantee that a strong roof by itself would reduce injuries much. A simple model for this is to imagine a person loosely strapped into a chair inside a metal box. If you turn the rig upside down, and drop the box onto a hard surface, there are two ways the person's head could be hit: the person could slip towards the roof, or the roof could crush in. It may be better to have some roof crush, to absorb the vehicle energy slowly, with a restraint that keeps the dummy in place. Volvo's answer to this is for the S80 and XC90 included seatbelt pre-tensioners, to keep the passenger from moving too much.

NHTSA needs to update FMVSS 216 to require more protection. I don't know about you, I would pay an extra few hundred dollars for a vehicle that would give me a better chance of surviving a roll-over. And regulations such as these hit all automakers equally, so no automaker will have much of a competitive disadvantage.

Ford, for its part, needs to enforce its internal safety design specifications, even if it costs more money. This is a beautiful example of "penny-wise pound-foolish". Ford has been ordered to pay out about $200 million in damages over this issue so far, and the Explorer's safety record continues to be tarnished.

UPDATE: Ford has issued a statement regarding this issue, here.

Simply strengthening the roof won't improve the safety of SUVs and other passenger vehicles in rollovers. Years of testing show strengthening the roof will not affect the outcome of the crash for the simple reason that the injury mechanics are not related to how much the roof is deformed in a rollover crash. We've looked at injury and fatality rates in rollovers involving vehicles that just meet the Federal standard to vehicles that have roof strengths that are multiples of the Federal standard and there isn't a difference.


NHTSA data from its Fatality Analysis Reporting System (FARS) shows that 81 percent of rollover fatalities involved unrestrained occupants.

The last point is key. Some people do not wear seatbelts while riding in an SUV because of a sense of perceived invincibility. People who wear seatbelts increase their chances substantially of surviving roll-over accidents.

1 comment:

AutoRants said...

Roof strength, or the lack of, has always bothered me. Ever since I saw a Toyota pickup roll over on the 101 Freeway in So.Cal, I have been acutely aware of the weakness in the roof structure of most vehicles.

The roof crush issue has become even more prominent with the dramatic increase in SUVs sales over the last ten years. SUV’s have to major factors going against them as far as roof crush goes – they have a high center of gravity, thus an increased chance of rolling over, and due to their profile, they usually have less strong roofs than comparable large sedans. Physics is working against them in many ways, their heft also increases the chance that they will collapse their own roof in a rollover accident.

When FMVSS 216 was introduced, many feared it would be the end of convertibles (there were few American convertibles in MY 1972), yet it did not. And engineering and safety has progress significantly in the last 30+ years. Hopefully NHTSA can find a way to reconcile safety, cost, and design issues to develop a safer standard without legislating-out convertibles or other vehicle types.

That seatbelt data is amazing! Wear your seatbelt...Darwin?