A B-pillar from a Forester involved
in a collision shows eight layers
of high-strength, high-tension
Photo: Ron Moore

The innovative Ring-Shaped Reinforcement Frame body structure provides certain Subaru models manufactured since model-year 2002 with some unique crash protection. It also presents us rescue workers with some unique extrication challenges.


The Ring-Shaped Reinforcement Frame is part of a structural body construction in which body side panels and the pillars around them are connected and reinforced to form three rings. The A-pillars and the front firewall structure make up one ring. Both B-pillars along with two structural frame members in the floorboard and two specially shaped structural members running across the roof area make up the center ring. The third ring is formed by the C-pillars and a strengthened lower rocker sill area. This construction design resists collision failure quite well and helps maintain passenger compartment integrity by dispersing the impact forces of the crash away from the occupants.




The federal government is encouraging better vehicle side-impact performance and standards requiring better roof crush performance. So we’ll see more of these types of reinforced pillars as well as the increased use of exotic martensite (boron) high-strength, high-tension steels. Extrication techniques are constantly evolving to handle improved construction methods.


Editor’s Notes:

  • Ron Moore’s article first appeared in Firehouse Magazine. We reprint it here by permission of the magazine and Ron Moore.
  • This article was written before or shortly after the introduction of the 2006 Subaru B9 Tribeca, which is why it isn’t included.
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