Regulators look to tighten the tops of cars

[Z-06]

Linkity

Regulators Look to Raise Bar On Vehicles' Roof Strength

March 3, 2008

EYES ON THE ROAD By JOSEPH B. WHITE

If you dropped a 2006 Volkswagen Jetta on its roof, and then did the same thing to a big, tough Dodge Ram pickup truck, which one would likely suffer less damage and do a better job protecting the passengers?

The answer, based on a federal test of roof strength, is the Jetta. If that doesn't make sense to you, take comfort in the fact that you aren't alone.

Since the early 1990s, car makers have dramatically improved the crashworthiness of the fronts, sides and rears of their cars, responding to the demands of consumers and regulators. But the strength of your vehicle's roof is governed by a standard that hasn't changed since Richard Nixon was in the White House. Despite years of pressure from safety advocates and insurers, the industry and regulators at the National Highway Traffic Safety Administration have stuck with the same relatively lenient standard since September 1973.

That looks like it's about to change. NHTSA in January proposed tougher roof strength standards and a more rigorous roof crush test that at least 75% of vehicles currently on the road would flunk if they were enacted tomorrow. What NHTSA will do could become clearer this summer after the agency digests comments on its proposal, which are due in mid-March.

The pressure for change of the nearly 35-year-old roof crush standard will only increase. The Insurance Institute for Highway Safety plans soon to release a report on roof crush safety and the group's president, Adrian Lund, says eventually the IIHS plans to add a roof crush test to its existing array of well-publicized front and side crash tests.

How many lives would a requirement for stronger roofs in cars and trucks save? That's just one of the areas of dispute in this contentious corner of the vehicle safety debate. The government estimates it could be as few as 476 people a year. Or it could be more than 1,000 people a year. It depends on how you count and who you count.

For consumers and lay people without engineering degrees, the roof crush issue is either a thicket of highly technical arguments, or a matter where the only question is why a common sense solution hasn't been ordered up.

The current rules require that vehicles weighing 6,000 pounds or less have roof designs that can withstand a force equivalent to 1.5 times the vehicle's weight -- a measure known as a strength-to-weight ratio, without crushing in by more than 5 inches.

Vehicles heavier than 6,000 pounds are exempted from the standard. That probably made sense in 1973, when passenger vehicles were virtually all cars. But in today's world, that standard effectively exempts the largest and heaviest pickups and sport utilities -- even though pickups and SUVs overall have higher tendencies to roll over than do sedans like the Jetta.

NHTSA's proposal would boost the minimum strength to weight ratio to at least 2.5 times the vehicle's weight, although the agency is looking at a figure as high as 3.5 times the vehicle's weight. In addition, NHTSA is pondering a new test that would apply crushing force to two sides of the roof, instead of just one.

Safety advocates and consumer groups have problems with the government's existing roof crush standard on several points. Exempting heavy vehicles is one. The minimum strength to weight ratio of 1.5 times the vehicle weight is another. The latest NHTSA proposal addresses both those complaints.

NHTSA's testing method is a third point of controversy. NHTSA assesses roof strength by pushing a metal plate down on one side of the roof. Safety groups say a "dynamic" test -- in other words actually putting the vehicle through a rollover -- is the right way to measure a vehicle's ability to protect occupants in such a violent crash. But NHTSA so far isn't considering a dynamic test.

Auto makers, individually and through the Alliance of Automobile Manufacturers, have evolved in their response to the roof crush issue over the years. For a time, some industry officials tried to argue that it wasn't roofs crushing in that hurt people. It was people, usually unbelted, hitting the roof that was the problem.

Now, the Alliance has moved to a different posture. The industry group hasn't issued a formal comment on NHTSA's latest proposal. But in the past, the industry lobby has stressed that roof strength is just one of several factors important to avoiding death in rollover accidents. The industry should get credit for the wider use of electronic stability control, which helps to avoid the sideways skids that often lead to rollovers, the Alliance's past comments suggest.

The Alliance emphasizes that if a more rigorous standard is adopted that the industry needs time to redesign vehicles to meet it, and some exemptions for certain types of vehicles that might never pass the test. Of concern are convertibles, not surprisingly, which NHTSA's proposal would exclude.

The industry also wants separate standards for "low roof line vehicles" and vehicles such as the Jeep Wrangler, that are basically open body trucks.

Auto makers warn that putting more steel in roofs will add cost and weight -- the latter problem compounded by the penalty exacted on fuel economy.

NHTSA says that raising the strength-to-weight ratio of a Ford Explorer to 3.0 would add $33 to $35, and up to 23 pounds of weight. NHTSA has estimated that overall, raising the roof strength to weight ratio for all vehicles to 2.5 would add an average of $11 per vehicle, although costs would vary by model. The Alliance has argued the costs would be more -- in a range from $55 to $185 a car to meet the 2.5 ratio standard.

This is a movie the auto industry has starred in before, quite reluctantly and painfully. It's true that in the car business, with margins that are narrow to non-existent, $55 to $185 a car is a serious issue for the bottom line.

But it's also true that these sorts of cost benefit analyses never look good when weighed against the value of a life, as they often are in courts of law.

In the meantime, anyone who wants a vehicle with a roof that meets or exceeds the proposed 2.5 strength to weight ratio in a one-sided roof crush test, NHTSA has provided a useful list in its proposed rule. (See the full proposal PDF)

• Send comments about Eyes on the Road to [email protected].

NHTSA'S TOP PERFORMERS

These vehicles performed the best is NHTSA's current roof test. Best car: VW Jetta (5.1) Best SUV: Volvo XC90. (4.6) Best pickup: Toyota Tacoma (4.4) Best Detroit brand: Ford 500 (Taurus) 3.9

Edited March 3, 2008 by smallchevy

[Robert Hall]

I think is more of a problem with trucks and SUVs than cars...trucks and SUVs have higher centers of gravity, and roll easily...and with their obesity, the big trucks and SUVs seem to collapse under their own weight...

[loki]

thi swould just add more weight unless better materials were used... but in both cases, higher prices. YIPEEE don't we all love regulations?! /sarcasm

[Newbiewar]

isnt it always great GM isnt on that list... i dont know how many times that GM gets to boast, ohh more regulations, well our company rule is still 2.5 times stronger then that!

but are they going to get noticed for their over promise additude... nope

[balthazar]

Did this refer to actual testing of the Jetta / Ram, of just compare curb weights vs. the federal roof strength standard? Why I am thinking: the latter.

Most cars have far more raked-back A-Pillars/windshields than trucks, and more than enough weight to crush this weak design feature as opposed to trucks which have more vertical A-Pillars (not to mention dead-vertical pillars everywhere else).

Almost all of the roof crush problem can be traced to markedly thinner structural & sheetmetal,... and more & more raked-back windshields, so no surprise the standard needs updating.

I'll happily point to the triple-wall, vertical A-pillar on my '59- the best design for crushproofing (AND visibility!). Leave the aerodynamics to the windshield and keep the structurals doing what they're there for: protection.

[pow]

Did this refer to actual testing of the Jetta / Ram, of just compare curb weights vs. the federal roof strength standard? Why I am thinking: the latter.

Most cars have far more raked-back A-Pillars/windshields than trucks, and more than enough weight to crush this weak design feature as opposed to trucks which have more vertical A-Pillars (not to mention dead-vertical pillars everywhere else).

Almost all of the roof crush problem can be traced to markedly thinner structural & sheetmetal,... and more & more raked-back windshields, so no surprise the standard needs updating.

I'll happily point to the triple-wall, vertical A-pillar on my '59- the best design for crushproofing (AND visibility!). Leave the aerodynamics to the windshield and keep the structurals doing what they're there for: protection.

Both. The Jetta requires 72,613 newtons to push the roof down by 5 inches; the Ram requires 37,595. This translates to an SWR of 5.1 for the Jetta, and 1.7 for the Ram.

The roof that can withstand the most weight tested so far is the XC90, at 90,188 newtons, or an SWR of 4.6 times the car's weight.

[Robert Hall]

Both. The Jetta requires 72,613 newtons to push the roof down by 5 inches; the Ram requires 37,595. This translates to an SWR of 5.1 for the Jetta, and 1.7 for the Ram.

The roof that can withstand the most weight tested so far is the XC90, at 90,188 newtons, or an SWR of 4.6 times the car's weight.

Truck roofs are particularly weak, I've seen countless rolled over pickups with the roof mashed flat down to the bottom of the side windows...the weight and weak pillars are probably to blame.. since trucks aren't unibody, there is no crash structure there...just a collapsible metal body on top of a heavy frame.

Edited March 4, 2008 by moltar