Traction Characteristics of Prepared Traffic Lanes

TRACTION characteristics of lugged and smooth tires were compared on prepared traffic lanes and on conventional seedbed conditions. Results indicated that elevated traffic lanes offer important traction advantages over seedbeds in wet soil conditions. In dry soil conditions, traction on elevated traffic lanes was sometimes less than on the seedbed conditions. A timeliness advantage in mobility for the elevated traffic lanes was found to be up to 2 days in extremely wet conditions. A non-elevated traffic lane showed no traction advantage in wet conditions. INTRODUCTION The potential advantages of the controlled traffic concept have been widely discussed. When "rootbed" and "roadbed" zones are distinctly separated, the desirable characteristics of each zone can be maintained. With this system of crop production, the detrimental effects of soil compaction on production can be minimized. The agronomic advantages of the uncompacted rootbed in the controlled traffic concept are not the only benefits. Prepared compacted traffic lanes offer potential for improved flotation, traction, and timeliness. The potential for traffic-related benefits has not been fully explored. PRIOR RESEARCH Various approaches to the controlled traffic concept have been investigated by many researchers (Taylor, 1983). Advantages of controlled traffic frequently cited include increases in crop yields of 20 to 50%, reduced requirements for deep tillage, reduced power and fuel requirements for crop production, and increased soil water holding capacity. However, references to the traffic-related benefits of controlled traffic are few. Several researchers have explored the controlled traffic concept using traffic lanes made from reinforced concrete (Kisu, 1971; Kisu, 1976; Kereselidze et al., 1974). These authors reported significant improvement in the operation of tea harvesting equipment on the concrete tread ways. Pollard and Elliott (1978) used a concrete treadway Article was submitted for publication in April, 1985; reviewed and approved for publication by the Power and Machinery Div. of ASAE in November, 1985. Presented as ASAE Paper No. 84-1031. The authors are: EDDIE C. BURT, Agricultural Engineer, and JAMES H. TAYLOR, Research Leader and National Technical Advisor, Traction and Controlled Traffic, National Soil Dynamics Laboratory, USDA-ARS, Auburn, AL; and LARRY G. WELLS, Associate Professor, Agricultural Engineering Dept., University of Kentucky, Lexington, KY. technique to evaluate the effects of soil compaction on barley production. They emphasized the increase in barley yield which resulted from the absence of soil compaction, but did not discuss traction or timeliness advantages. Taylor (1982) discussed the potential improvement in traction resulting from operation of pneumatic tires on compacted soil. He mentioned the lack of research results which directly address the traction, flotation, and timeliness of operations on controlled traffic lanes. Therefore, the objectives of the research reported in this paper were to: 1. Determine the net traction and tractive efficiency of pneumatic tires operating on elevated and nonelevated traffic lanes and on a simulated seedbed condition for selected soil types and soil moisture conditions. 2. Determine the time delay following a flooded soil condition for adequate mobility on elevated and nonelevated traffic lanes and on the simulated seedbed. PROCEDURES This research was conducted in the soil bins at the National Soil Dynamics Laboratory. Soils used for the elevated traffic lane tests were Decatur silt loam, Davidson clay, and Hiwassee sandy loam (Batchelor, 1968). The Decatur silt loam soil was subsequently prepared with a non-elevated traffic lane. Soils were prepared using soil bin preparation equipment to simulate a traffic lane and seedbed condition. The prepared seedbed condition had approximately 25 cm of soil over a plowpan, simulating a field that had been plowed and subsequently disked. Traffic lanes were built by placing soil on the lane area, leveling the surface, and then compacting the soil in approximately 8-cm layers. The final compacted elevated traffic lane was approximately 15 cm higher in elevation than the surrounding seedbed. Final surface elevation for the non-elevated traffic lane was the same as for the surrounding seedbed. All tests for this study were conducted using a single wheel agricultural tire test machine. This machine operates a test tire under computer control and has provisions for measuring the variables needed to evaluate the tire performance (Burt et al., 1980; Lyne et al., 1983). Tires used for this study were a commercially available 18.4-38 bias-ply tire with R-1 tread supplied by Firestone Tire and Rubber, and a 18.4-38 smooth tire modified and furnished by Caterpillar Tractor Co.* The smooth *Use of a company name does not imply USDA or University of Kentucky approval or recommendation of the product or company to the exclusion of others which may also be suitable. Vol. 29(2):March-April, 1986 393 tire had been buffed smooth and recapped to original lug dimensions with solid tread rubber (no lugs). Each tire was operated at an inflation pressure of 110 kPa and at a dynamic load of 23.3 kN. The rolling radius needed for travel reduction calculations for each tire was determined at zero net traction on a rigid surface. Inflation pressure and dynamic load were controlled at the desired levels during the radius tests. All tests on soil were run as continuously varying travel reduction tests. The travel reduction was initially set at approximately negative 5% and was then slowly and continuously increased through zero to approximately 40%. Dynamic load and inflation pressure were held constant during each test. Variables needed to determine net traction and tractive efficiency were recorded throughout each test run. The same test procedure was followed for both the traffic lane and the seedbed areas. Tire performance was evaluated on each test soil condition at three different soil moisture conditions. A saturated condition was developed by adding water for several hours from overhead until the soil bin was flooded. In bins prepared with elevated traffic lanes, the traffic lane extended 5 cm above the surface water level. For this condition, the elevated traffic lane was also saturated up to about 5 cm below the surface. Traction performance tests were conducted at this moisture condition to simulate field conditions immediately following a heavy rainfall. The second and third moisture conditions resulted from a delayed time period for drainage and drying following the flooded condition. The time delay period was adjusted for the different soils based on the drainage and drying rate. Soil moisture content at each test condition is given in Table 1. Approximately one-third of each soil bin was tested at each moisture condition. Accumulation of mud on the surface of the tires operated in wet soil conditions causes wide variations in tire performance. These variations presented difficult problems in the analysis of data. Therefore, the curves presented in this paper were drawn to best represent the overall trends in performance. RESULTS Decatur Silt Loam—Elevated Lane Fig. 1(a) shows net traction vs. travel reduction for the lugged tire run on Decatur silt loam on the elevated traffic lane and on the seedbed areas. This test was run 15 [TRAFFIC LANE. SEEDBED