Track Surfaces & Test Areas

Three Mile Oval


The three-mile oval test track at Navistar Proving Grounds consists of three lanes of asphalt road surface designed to carry all light vehicles and heavy truckloads of up to 32,000 pounds per axle. Each of the three lanes has specific uses designed to maximize track utility and safety. As a vehicle moves radially outward in the corners, it encounters a progressively steeper bank. The oval is used for a wide variety of tests as well as general pretest warm-ups and conditioning work. Its limited-access feature allows engineers and technicians to concentrate on subtle NVH and ride/handling problems as required.

The west straight, south curve and east straight are all 4,220 feet (0.8 mile) long with only the north curve measuring a shorter 3,170 feet (0.6 mile). All lanes are 12 feet wide. Because of its extremely flat profile, most brake testing is performed on the east straight.

Should a test procedure require speeds in excess of 90 mph in the straights or 80 mph in the corners, special precautions in the form of track warnings, competition seat belts, strobe lights, roll bars, helmets, etc., may be required. In special cases, the oval can be closed to other traffic to accommodate unusual events such as reverse direction or multi-lane tests.

Durability Roads


Durability roads contain a variety of surfaces designed to push the limits of vehicle structural integrity. These surfaces or “events” include inverted chatter bumps, impact bumps, light and heavy vehicle cobblestones, resonance and undulating roads, sine wave roads, and a variety of gravel and cross-country roads. These surfaces increase the frequency of inputs typically found on public roads for the purpose of accelerated mileage accumulation. This allows a test of only a few weeks’ or months’ duration to represent the total mileage a vehicle would experience in its lifetime.

Included in the durability area is a 20-foot-wide by 252-foot-long water basin available for accelerated corrosion testing, water intrusion evaluation and brake soaking. Either pure water or saltwater solutions are available. The drive-through depth is 64 inches, although damming can increase the fording limits to 84 inches.

Navistar can correlate a customer's typical operating environment to an accelerated structural durability procedure and route through a road profile determination process. Strain gage and acceleration data is gathered over both the road surfaces typically encountered during the vehicle’s life and the proving grounds’ durability events. The data is then analyzed using rain flow techniques. The result is a correlation of accelerated test miles to "real world" miles for the specific components measured.

Navistar also maintains a complete and accurate duplication of the Altoona, Pennsylvania, bus route within the structural durability test area. This area allows bus manufacturers to validate new components or entire vehicles prior to certification.

Vehicle Dynamics Area


The New Carlisle skid pad provides a variety of low-coefficient surfaces as well as a high-coefficient asphalt area suitable for "braking in a curve" maneuvers, J-turns, figure-8s and tight-radius lateral-acceleration tests. The pad is roughly trapezoidal shaped with an overall length of 1,400 feet and major width of 300 feet. A turnaround is provided on the end of the pad with direct access from the three-mile oval track to allow speed stabilization and acceleration flexibility. Built into the edge of the skid pad are automatic sprinklers designed to flood the low coefficient surface for a length of 600 feet.

The entire pad has a 0.5% slope to facilitate rapid water drainage and evaporation. Should water coverage be required in areas not covered by sprinklers, a tanker truck and driver can be provided. A fully instrumented skid trailer ensures paved surfaces are of known friction coefficients. Speed limits for vehicle testing are a function of test surface, vehicle type and test type. The following test surfaces are present on the large pad: asphalt, jennite, tile and urethane.