'Pave the Gravel Traps, Cushion the Oval Walls' Says Ex-Racer Fitch
13 August 2000
'Pave the Gravel Traps ... Re-think the Tire Barriers, Cushion the Oval Walls," Says Ex-Racer Fitch
LIME ROCK, Conn., Aug. 11 "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.