Foam buns are created as the working material for a soft wall system.
Another type of soft wall is called the Impact Protection System (IPS). Eurointernational has developed a soft wall made 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 long, 3 feet 9 inches tall, and weigh 475 pounds. To install these segments, holes are drilled in the concrete wall and cables are used to tie the segments to it. The individual segments are tied together with strong nylon webbing material to form a continuous wall.
The IPS is the result of many years of research, studies, tests, and modifications. This barrier has the official approval of the FIA and has also been approved by the FIK (Karting) and FIM (motorcycles).
According to the manufacturer, this barrier is able to receive three impacts at the same place without needing to be replaced. The barrier returns to the original configuration after each impact, with an equal amount of energy absorbed each time. The barrier segments for racetracks come in two configurations-standard and reinforced. The reinforced barrier is identical to the standard barrier except it is wrapped in a double layer of smooth rubber material; the standard barrier is wrapped with just one.
Another popular soft wall is the block foam-style wall. As opposed to the other two types, this wall uses only the absorber foam to make up the walls. Some tracks have used large blocks of Styrofoam or polyethylene as the absorbing foam.
A group of NEMA winged Midgets tangle and scatter foam during a race at Oswego Speedway. N
This is certainly the least expensive way to accomplish the soft wall, but it has some drawbacks. The first drawback is that the absorbing foam takes serious abuse during the crash because there is no facing wall. This abuse usually leads to the destruction of the foam while spreading it all over the track. The result is a cleanup problem-and in some stock car tests, large chunks (5-20 pounds) have broken off and flown into the stands.
In addition to Styrofoam and polyethylene, other types of foam are being considered for use in both the block and engineered systems with facing walls. These foams are engineered specifically for energy dissipation. Styrofoam and other foams were used because they were readily available. These engineered foams can be custom made to the needs of the wall systems. A bun of the engineered foams can come as large as 4 feet high by 6 feet wide by 210 feet long. Although it's next to impossible to move a bun that large, it shows that the material is there for a more engineered application.
The End Users A survey of racetracks has found that there are many different approaches to keeping drivers safe through the use of energy dissipation.
Stafford Motor Speedway is a half-mile asphalt track in northern Connecticut. The track employs a more traditional energy-absorbing barrier. The outer wall consists of steel guardrails with down posts that go deep into the ground. Though many tracks have gone to cement in the corners, Stafford has stayed with the guardrail in all but one corner. In fact, Stafford is replacing the guardrail with steel I-beams. "I have seen our wall move 4 feet to 5 feet to dissipate the energy of a crash," says Stafford's General Manager/ CEO Mark Arute. "Our system moves more than a SAFER barrier wall. This system requires a lot of maintenance, but we have never had a failure. Every so often, we will have to take some equipment and reset the wall and tamp in the dirt behind it." Arute says Stafford is investigating the installation of the SAFER barrier in the corner with the cement walls.