Axle load

About: Axle load is a research topic. Over the lifetime, 2178 publications have been published within this topic receiving 16487 citations.

Subsoil compaction by vehicles with high axle load—extent, persistence and crop response

Abstract: Extent and persistence of soil and crop responses to subsoil compaction caused by vehicles with high axle loads are reviewed and methods to protect the subsoil from permanent deterioration are discussed Traffic by vehicles with high axle loads on soils with high moisture contents generally causes deep subsoil compaction At an axle load of 10 Mg, compaction typically penetrates to a depth of 50 cm With still higher loads, compaction to a depth of 1 m has been reported Subsoil compaction is very persistent At depths of more than 40 cm it is virtually permanent even in clay soils in regions with annual freezing Deep subsoil compaction also causes persistent and possibly permanent reductions of crop yields Complete amelioration by mechanical loosening is usually impossible and definitely expensive From a soil productivity point of view, limits for mechanical stresses in the subsoil are needed These may have the form of axle load limits for the vehicles or a combination of limits for the axle load and for some other important factors, such as the ground contact pressure of the running gear or the per cent water saturation of the soil at the time of trafficking Guidelines for such limits should preferably be worked out in an international joint effort

Effects of heavy-vehicle characteristics on pavement response and performance

Abstract: The high wheel loads of heavy trucks are a major source of pavement damage by causing fatigue, which leads to cracking, and by permanent deformation, which produces rutting. Among heavy trucks, all do not cause equal damage because of differences in wheel loads, number and location of axles, types of suspensions and tires, and other factors. Further, the damage is specific to pavement properties, operating conditions, and environmental factors. The mechanics of truck-pavement interaction were studied to identify relationships between truck properties and damage (fatigue and rutting). Computer models of trucks were used to generate wheel load histories characteristic of the different trucks and operating conditions. Influence functions, obtained from rigid and flexible pavement structural models, were used to predict responses along the pavement resulting from the truck motions. The pavement responses were evaluated to estimate overall pavement damage caused by each truck. The study assessed the significance of truck, tire, pavement, and environmental factors as determinants of pavement damage. Maximum axle load and pavement thickness have the primary influences on fatigue damage. Truck properties, such as number and location of axles, suspension type, and tire type, are important but less significant. High temperatures in flexible pavements and temperature gradients in rigid pavements adversely affect the damage caused by truck wheel loads with a fairly strong interaction. The report discusses and quantifies the influence of these variables.

Interaction Between Heavy Vehicles and Roads

Abstract: This paper discusses road damage caused by heavy commercial vehicles. Chapter 1 presents some important terminology and a brief historical review of road construction and vehicle-road interaction, from ancient times to the present day. The main types of vehicle-generated road damage, and the methods that are used by pavement engineers to analyze them are discussed in Chapter 2. Attention is also given to the main features of the response of road surfaces to vehicle loads and mathematical models that have been developed to predict road response. Chapter 3 reviews the effects on road damage of vehicle features which can be studied without consideration of vehicle dynamics. These include gross vehicle weight, axle and tire configurations, tire contact conditions and static load sharing in axle group suspensions. The dynamic tire forces generated by heavy vehicles are examined in Chapter 4. The discussion includes their simulation and measurement, their principal characteristics, the effects of tires and suspension design on dynamic forces, and the potential benefits of using advanced suspensions for minimizing dynamic tire forces. Chapter 5 discusses methods for estimating the effects of dynamic tire forces on road damage. The two main approaches are either to examine the statistics of the forces themselves; or to calculate the response of a pavement model to the forces, and to calculate the resulting wear using a material damage model. The issues involved in assessing vehicles for 'road friendliness' are discussed in Chapter 6. Possible assessment methods include measuring strains in an instrumented pavement traversed by the vehicle, measuring dynamic tire forces, or measuring vehicle parameters such as the 'natural frequency' and 'damping ratio'. Each of these measurements involves different assumptions and analysis methods for converting the results into some measure of road damage. Chapter 7 includes a summary of the main conclusions of the paper and recommendations for tire and suspension design, road design and construction, and for vehicle regulations.

A study of dynamic wheel forces in axle group suspensions of heavy vehicles

Abstract: A wheel force transducer was used to measure dynamic wheel loads for speeds ranging between 40 km/h and 80 km/h over road surfaces ranging from as-new construction to the maximum tolerable roughness as measured using the NAASRA roughness meter. The effects of tyre inflation pressure and axle group load were taken into account and a factorial experimental design was used to determine dynamic loading, expressed as a form of coefficient of variation termed the dynamic load coefficient (dlc), as a function of speed and roughness for each suspension type. It was found that, for practical purposes, the dlc for each suspension type is a function of the product of the speed and the square root of the NAASRA roughness value. The centrally-pivoted drive axle suspensions (walking beam and single point types) show a dlc increasing with spring stiffness. Although the trailer suspensions and the torsion bar drive axle suspension showed, in general, lower dlc's than the centrally-pivoted drive suspensions, it was concluded that the level of dynamic loading generated by all suspensions is large. Three out of five drive axle suspensions were found to cause severe dynamic pavement loading. At least one of these does not comply with current Australian regulations for load sharing suspensions, and a quantitative test of dynamic loading is suggested. Most suspensions were found to share the load between the wheels to within 10 per cent of an equal share and this level is proposed as a quantitative criterion of load sharing ability. One currently accepted type did not load-share adequately and it is concluded that a test is needed and in some cases proper fitment of the suspension to the chassis needs to be ensured. (Author/TRRL)