Types of Soft Walls

Soft walls are typically built of some kind of crushable material that can absorb the impact of a car at high speeds, dissipating the force of the crash throughout the material. Widespread implementation of soft walls on NASCAR tracks is probably still several years away. However, at least one track has already replaced small portions of concrete walls with soft walls. Here's a look at a few of the soft walls in use and in development:

• Cellofoam - This is an encapsulated polystyrene barrier -- a block of plastic foam encased in polyethelene. Lowes Motor Speedway, a NASCAR race track, has already installed small segments of Cellofoam on the inside retaining wall of turns two and four.

• Polyethylene Energy Dissipation System (PEDS) - The Indy Racing League (IRL) has been funding the PEDS system, which uses small polyethylene cylinders inserted inside larger ones. Designers of PEDS believe the system increases the wall's ability to withstand crashes of heavy race cars. Indianapolis Motor Speedway has already installed a PEDS on the fourth turn of its track.

• Impact Protection System (IPS) - Eurointernational has developed a soft wall made out of layered PVC material placed on a honeycomb structure. This inner piece of the wall is then wrapped in a rubber casing. The barrier walls come in segments that are 5 feet 9 inches (1.8 meters) long and weigh 475 pounds (215 kg). Holes are drilled in the concrete wall and cables are used to tie the segments to it. Click here for more information about the IPS.

• Compression barriers - Another soft-wall idea has been proposed by John Fitch, a Connecticut highway-safety expert. His idea is to place cushioning materials, such as tires, against the concrete wall, and then cover those cushions with a smooth surface that would give when impacted, and then pop back out to its previous shape once the impact is over.

According to NASCAR Chief Operating Officer Mike Helton, NASCAR has been researching soft-wall designs for three to four years, but hasn't found one suitable for its race tracks. Most of the designs they have tested have some prohibitive flaws. Some of the walls are made of material that breaks up, scattering across the track and delaying the race. Earnhardt, one of the biggest critics of new safety devices, once said that waiting for a splintered soft-wall to be cleaned up would be worth it if it saved someone's life.

Another criticism of soft walls is that a car can bounce off a soft wall and back into oncoming traffic, posing a danger to a greater number of drivers. Also, in NASCAR races, cars often scrape against the outside wall. Some believe that a soft-wall material would grab a car scraping the wall and cause it to suddenly stop. Another possibility is that a car crashing into a soft wall could get caught in the material, and that quick stop could concentrate the energy of the crash and cause even more damage.

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