LIME ROCK, CT , August 11, 2000 -- "Gravel traps on road racing courses should be paved over so drivers can steer, brake and recover" says veteran racing driver and barrier designer John Fitch. A new videotape produced by Fitch shows the ...
LIME ROCK, CT , August 11, 2000 -- "Gravel traps on road racing courses should be paved over so drivers can steer, brake and recover" says veteran racing driver and barrier designer John Fitch. A new videotape produced by Fitch shows the ineffectiveness of gravel traps, the misuse of tire barriers and the deadly exposure to rigid walls in contemporary racing.
Fitch's conclusions are shared by the Racing Safety Advisory Board, consultants to the newly-formed Briggs Cunningham III Foundation. This foundation is being established by the son of long-time racing team owner Briggs Cunningham and is dedicated to the development of effective new energy absorbing barriers. Members of the Racing Safety Advisory Board include Mario Andretti, Carroll Shelby, Dan Gurney, Phil Hill, Stirling Moss, Paul Frere, Benny Parsons, Dr. Terry Trammel, Dr. Steve Olvey, William and Douglas Milliken, John Gorsline, Brock Yates, Karl Ludvigsen and Chris Economaki.
Gravel trap incidents shown in the video include a car tripping and rolling in gravel at Spa, the Michael Schumacher injury at Silverstone, Hakkinen skating straight ahead in Germany and Gonzalo Rodriguez imperceptibly slowing while "gravel-planing" into a tire wall and the concrete barrier behind it at Laguna Seca.
All of the gravel trap incidents show cars that might have regained control but for the gravel traps. "When a driver gets into the gravel," says Fitch, "he becomes a passenger, unable to brake or steer. Schumacher could easily have turned away from the wall well within the radius F1 cars can negotiate on pavement, if not for the gravel trap. But instead his momentum carried him arrow straight across a wide gravel trap and head-on into the barrier with little loss in speed despite locked brakes. When Hakkinen blew a tire, he was unable to turn away, exactly as in Schumacher's case."
Fitch, who spent 30 years in the field of highway safety, notes that tests of gravel traps by the U.S. DOT (Transportation Research Record 1233) indicate a deceleration of only 0.5 G, or the rate of moderate braking for a passenger car. The full scale study determined that even this modest rate does not begin until the car has slowed to 50 mph. This compares to a 3 to 4 G braking capability for Formula One cars on a paved surface. Then there are the lesser problems of cars being eliminated from races due to damage caused by the gravel, or by simply getting stuck.
Both the Schumacher and the Hakkinen incidents also clearly show the inadequacy of the energy-absorbing capability of tire barriers for high speed, head-on impacts. The depth of tire walls is limited by the FIA to prevent them from bunching up under cars and vaulting them over the top. However, that results in abruptly arresting cars at intolerable rates. This is illustrated in the video beyond debate. The use of shallow tire walls as crash cushions for speeds over approximately 50 MPH will not arrest a car within a rate that will insure survival without serious injury, as Newton's Laws confirm.
Even more dramatic and equally convincing are the high-speed, high- angle impacts resulting in the counter-productive use of tires to face the surface of guardrails and walls. When tire walls are misapplied in this manner to function as re-directing barriers, they are penetrated locally and snag cars abruptly, imparting life-threatening G peaks. If this does not stop the car, it violently rejects and spins it across the track into traffic. This is not theory but is abundantly clear in repeated real-life scenes in the Fitch videotape.
In spite of the shortcomings of tire barriers, sanctioning bodies do not take them out because they do have a function when hit at low speeds - approximately 50 mph or less. They function best at low speed, high angle, head-on impacts- and when hit at any angle at low speed they lower the G-level and reduce car damage, which would not in any case be significant.
There are two basic types of barriers: one is the energy-absorbing crash cushion for high angle, head-on impacts. In the absence of an effective crash cushion, tire walls are used for the final arresting medium at the perimeter of gravel beds. However, as noted, tire walls lack the necessary depth to stop cars from racing speeds at acceptable rates. (A concept to replace tire walls in this application awaits development.)
The second type is the redirecting barrier (walls and guardrails) for shallow angle impacts whereby cars are forced into a parallel direction at lower Gs than stopping them would generate. In highway practice, the design objective is to locate redirecting barriers so they will not be hit at angles over 25-degrees. However, when hit at higher angles as in the case of Adam Petty and Kenny Irwin, the consequences are devastating. (A design to reduce the initial G peaks upon impact with redirecting barriers is available.)
Though great strides have been made in modifications to the cockpit and cars themselves, Fitch remains convinced that the greatest opportunities lie in barrier innovation where Gs can be minimized over infinitely greater distances. However he believes his Driver Capsule design successfully addresses the two elusive challenges in biomechanics: the spatial stabilization of the helmet and upper torso to prevent shear forces acting on the neck, and the regulation of accelerations impinging on the helmet, thus reducing exposure to brain shock trauma.
Mr. Fitch is road racing's elder statesman and designer of energy-absorbing barriers for race courses and the highway. His invention, the yellow barrels in front of bridge abutments, have saved thousands of lives in 50 states over the last 30 years. At age 82, the former P-51 fighter pilot is still racing, and drove a Mercedes-Benz 300SL roadster at last year's Labor Day vintage races at Lime Rock, Connecticut. The following weekend he received The Cunningham Sportsmanship Award at Watkins Glen from the Sportscar Vintage Racing Association. At Goodwood in June, he drove the '52 Mercedes he raced in the Panamerica and is entered in the Laguna Seca Historics in August.