Automobile Proving Ground

a location equipped for testing automobiles. The first automobile proving ground was built in 1924 by General Motors in Milford, USA. In subsequent years new testing areas and installations were added to it. Many European companies also built automobile proving grounds: Linas Montlhérj (France) in 1924–25, Motor Industry Research Association (MIRA, in England) in 1949–50, and others. Several automobile proving grounds have been built in Japan (Mitsubishi, Nissan Motors, Toyota in 1961–62) and in Australia (Holden, 1960). In 1964 the USSR constructed the Central Scientific and Research Automobile Institute (NAMI), which belongs among the largest in the world.

An automobile proving ground is a complex of test and service roads, installations, buildings, and structures which make it possible to conduct the necessary sorts of tests on cars of various types under conditions that guarantee comparability of results obtained at different times and assure the safety of the tests and an absence of obstacles. The automobile proving ground provides rapid circuit roads or speedways for tests involving long runs at high speed; “dynamometric” roads for testing fuel consumption and traction, speed, and braking characteristics; routes with various uneven hard surfaces as well as dirt roads and dirt and stone roads for testing fatigue strength and reliability (durability); and stretches of road with various types of artificial irregularities for testing driving smoothness and maneuverability and for determining the fatigue strength of parts and assemblies. Besides roads, automobile testing grounds also have the following testing installations: water basins; inclines of various steepnesses; areas and equipment for testing the construction safety of cars (collision with stationary obstacles, overturning, and the like); horizontal sites with hard, smooth surfaces for determining the maneuverability and stability of automobiles and tractor-trailer combinations; stretches of rugged terrain and natural and artificial obstacles for testing the roadability of automobiles; dust, rain, and climatic (cold and tropical) test chambers; wind tunnels; and the like. Automobile proving grounds also have garages, preventive maintenance shops, repair shops, storage depots, gas stations, meteorological and traffic monitoring points, and other laboratory, service, production, and auxiliary premises.

High-speed circular roads with hard, smooth (cement, concrete, or asphalt) surfaces are built up to 8 km long abroad, up to 14 km in the USSR, and up to 10 m wide. The road, unlike racetracks, has up- and downgrades that are typical for major highways of the first and second categories. A “dynamometric” road is a straight road with a level cross section and hard, even, cement-concrete or bituminous-concrete surface. The length of the road at the various automobile proving grounds ranges from 1.5 km (MIRA in England, Ford in the USA) to 3.6–4.2 km (Chrysler and General Motors in the USA) and 4.7 km (Automotive Scientific and Research Institute, USSR); the roadbed width ranges from 6 to 11 m, with one or two traffic lanes (that is, with a dividing strip). At their ends are return loops or areas usually designed for a speed of up to 40–60 km/h. A “Belgian road” is a road paved with uneven slabs of stone which reproduces the old paved roads of Europe, especially those of Belgium. Small surface irregularities are introduced through varying the levels of the adjacent slabs within a 25–mm limit. Large irregularities are created in the form of unevenly distributed bumps and dents with smooth contours and a depth of up to 75 mm. The stone slabs are set (with large gaps) in a sand-cement solution over a concrete foundation. Driving approximately 1,600 km on a “Belgian road” is enough to bring out defects that may be encountered in a passenger car during its entire lifetime on ordinary roads. For trucks this figure is usually doubled. A concrete road with short undulations has wavelike elevations of a regular nature that cause resonance oscillations in the automobile and in its individual assemblies and systems. The spacing of the undulations is 76±5 cm and their height 25 mm. The undulations are arranged perpendicularly to the axis of the road at a width of 3.3 m; on the remaining part of the roadbed (1.2 m) they run at a 68° angle to the axis of the road in order to shift the phase of the influences of the disturbing undulations to the wheels of the right and left sides of the automobile. A road with sinusoidal waves has a concrete surface with smooth undulations of a sinusoidal profile. The spacing of the undulations is 1 to 15 m, and their amplitude (extent) up to 400 mm (at maximum spacing). The undulations are arranged perpendicularly to the axis of the road and have at times a slanting or herringbone-like arrangement. A road with protuberances of various configurations is built with spherical segments, truncated pyramids, parallelepipeds, or railroad ties of varied heights and cross sections placed in various ways on the surface of the road. The surface of a noise-testing road (unlike that of a “Belgian road”) is made of granite slabs that are set on one level. Interacting with the wheels of an automobile, the microirregularities engender vibration and noises. To reverberate the noise made by the automobile, smooth walls of a fixed height are sometimes installed along the noise-measuring road. Cobblestone roads are made of naturally rounded stones of great durability. The paving of the roadbed is either level or contains irregularities of a given profile. Stone and dirt roads also include stretches completely unsuitable for travel (deep, loose sand, field, marshland, and snow-covered terrain). They are used for testing automobiles under especially difficult conditions.

Among test installations at automobile proving grounds are test upgrades—artificial ones with a hard surface or natural ones on rugged terrain; water basins (0.1 to 4 m deep) for assessing the water tightness and “fording capability” of automobiles; mud bath—tubs filled with mud the level and consistency of which can be regulated; and devices for determining the stability of automobiles exposed to strong crosswinds (accomplished by a series of air blowers placed along several dozen meters of the test road).