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Traffic load is one of the important external loads of bridges and simulating the site-specific traffic load is important for bridge condition assessment. This study proposes a new microscopic model to simulate the stochastic traffic load of any time period at bridge site based on weigh in motion (WIM) data. A model for simulating the microscopic interaction between vehicles was first proposed, by which free driving, car following and sudden braking can be reasonably simulated. Axle-weight information from the WIM data was embedded into the model to precisely simulate the vehicle load. A new vehicle sequence generation method based on WIM data was then proposed to generate the site-specific vehicle sequence of any time period with consideration of non-stationarity. Finally, a framework for simulating the site-specific stochastic traffic load is established. The proposed framework is validated through application based on realistic WIM data in traffic-flow simulation and load effect quantification. Comparisons of simulation results with the existing methods were also conducted to show the reasonability and novelty. The results indicate that the proposed framework can produce reasonable site-specific stochastic traffic load over any time period based on WIM data. [ABSTRACT FROM AUTHOR]

Firstly, the application and research of steel switch sleeper are introduced, a series of problems in the application of existing steel switch sleeper are proposed, and a new type of steel switch sleeper with integral casting type is designed. The new steel switch sleeper material adopts QT400 - 18 and its section size is comparable to that of ordinary concrete sleeper, which does not affect the tamping of the large machine. Subsequently, the torsional vibration mode with main vibration frequency of 127.4 Hz and 130.9 Hz and bending vibration mode with main vibration frequency of 169.7 Hz are calculated and proposed for the new steel switch sleeper, and other high-frequency vibration modes mainly come from the vibration deformation of the free end at the top of its sidewall. Finally, in order to study the force and deformation characteristics of the new steel sleeper in practical application, the static model of the new steel sleeper in practical application is established by using the finite element method, and on this basis, the influences of the axle load, passing speed and stiffness of the lower bed of the steel sleeper on its own force and vertical displacement value are studied. According to the calculation: the strength of the new steel sleeper meets the requirements, and the self-deformation is small; when the axle load of the train is 17 t and the passing speed is 80 km/ h, the maximum equivalence force of the new steel sleeper is 64.4 MPa, the maximum vertical displacement of the top surface of the rail head is 1.42 mm, and the maximum vertical displacement of the new steel sleeper is 1.36 mm; when the passing speed is only increased to 120 km/ h, the force of the new steel sleeper is increased by 16.7% and the displacement index is increased by 16.2%; when the axle load of the train is only increased to 29t, the force of the new steel sleeper is increased by 71.3%, and the displacement index is increased by 71.1%; when the stiffness of the bottom track bed is increased by 1 time, the force of the new steel sleeper is increased by 22.5%, and the displacement index is decreased by 12.7%. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, an investigation was conducted to assess the performance of artificial intelligence (AI) and machine learning (ML) methods with distinct characteristics in various problem scenarios. Reinforcement tensile forces play a significant role in the design and performance of retaining walls (RWs). These are crucial for the stability and structural integrity of the retaining walls, preventing wall failure. For this, an attempt was made to predict the reinforcement tensile forces of the back-to-back mechanically stabilized earth (MSE) walls under train loading, which are necessary for upkeeping the transportation infrastructure. Six innovative models were created to counter this challenge that combines AI and ML techniques, i.e., LR, SVM, ANN, ANFIS, ANN-GA, and ANFIS-GA. Consequently, the genetic algorithm (GA) technique was also used to integrate new models, such as GA-ANN and GA-ANFIS. The input data for the models were derived from the parametric study conducted in the finite element analyses. Statistical measures, including root-mean-square-error (RMSE), mean-absolute-error (MAE), and coefficient-of-determination (R2), were analyzed and compared across multiple baseline methods to verify the accuracy of the suggested model. Results show that the proposed model's (ANFIS-GA) accuracy (R2) is 0.9876 and errors (RMSE and MAE) are 0.0191 and 0.0122, respectively. This model outperforms the baseline models in all relevant respects and shall precisely predict the tensile forces of the back-to-back MSE walls. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive mechanistic-empirical assessment of axle load legal limits policy on Brazilian roadways, considering the intricate balance between enhanced freight transportation and potential pavement deterioration. Focusing on the prevailing flexible pavements, the study explores factors such as asphalt concrete stiffness, thickness, and axle-load increments, accounting for variations in tire-load and pressure. The analysis reveals complex relationships between these factors and their impact on pavement distress mechanisms, particularly fatigue cracking and rutting. The investigation highlights the substantial influence of axle load legal limits adjustments, even seemingly minor ones, on pavement damage, ride quality, safety, and operational efficiency. A calibrated model for assessing mechanistic-empirical load equivalency factors (LEFs) was developed, offering insights into the disparities between the model and existing empirical equations used in the Brazilian Pavement Design Guide (BPDG). This comparison underscores the potential underestimation of axle load legal limits adjustments in the current approach, emphasizing the importance of informed decision-making in transportation policy. In conclusion, this study provides critical insights for policymakers and engineers while considering axle load policy adjustments. The findings emphasize the significance of accurate engineering considerations to sustainably balance economic growth, road safety, and efficient freight transportation within Brazil’s evolving road network.

The success of the mechanistic-empirical pavement design guide implementation depends largely on a high level of accuracy associated with the information supplied as design inputs. Truck axle load spectra play a critical role in all aspects of the pavement structure design. Inaccurate traffic information will yield an incorrect estimate of pavement thickness, which can either make the pavement fail prematurely in the case of under-designed thickness or increase construction cost in the case of over-designed thickness. The primary objective of this study was to create an accurate traffic design input module, and thus to improve the quality of pavement designs. The traffic input module was created with the most recent data to better reflect the axle load spectra for pavement design. The unclassified vehicles by weigh-in-motion devices were analyzed and a neural-network-model-based classification method was utilized to determine the appropriate allocations of unclassified vehicles to truck classes. The updated truck traffic information includes average annual daily truck traffic, truck volume monthly adjustment factors, truck volume lane distribution factors, truck volume directional distribution factors, truck volume class distributions, traffic volume hourly distribution factors, distributions of for single-axle, tandem-axle, tridem-axle, and quad-axle loads, average axle weight, average axle spacing, and average number of axle types.

Copyright of Agriscientia is the property of Revista AgriScientia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Forestry Society of Croatia / Sumarski List Hrvatskoga Sumarskoga Drustva is the property of Forestry Society of Croatia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A bridge influence line (BIL) and a bridge influence surface (BIS) reflect the relationship between the bridge responses and the loads on the bridge and have been commonly used in techniques such as bridge damage detection, bridge safety evaluation, bridge model correction, bridge weigh-in-motion, and so on. Conventionally, a BIL can be extracted from the bridge response under a moving vehicle with known axle loads, while a BIS can then be obtained by lateral interpolation from BILs obtained for key transverse positions. However, in the traditional BIL-extracting methods, the transverse distance between the coaxial wheels was not considered; that is, the coaxial left and right wheel loads are simply treated as one concentrated load (usually referred to as the axle load). Therefore, the obtained BIL is the bridge response under two loads rather than one. Hence, errors may be introduced to the obtained BILs and propagated to the interpolated BIS. Moreover, the potentially significant effect of the unbalance of coaxial wheel loads on BIL identification is ignored. In this research, a new method for determining a genuine BIL and BIS is proposed. The wheel load rather than the axle load was taken into calculation in this method, where the effect of the transverse distance between the coaxial wheels and the unbalance of the coaxial wheel loads was naturally taken into consideration. Laboratory experiments and numerical simulations were performed to verify the effectiveness of the proposed method. Furthermore, a comprehensive parametric analysis was conducted to investigate the effects of some important parameters such as vehicle velocity, lateral deviation of the center of gravity of vehicles, axle count, and road surface condition on the identification performance. The results show that the BIL and BIS can be identified with satisfactory accuracy. Both the bridge influence line (BIL) and the bridge influence surface (BIS) have been commonly used in techniques such as bridge damage detection, bridge safety evaluation, bridge model correction, and bridge weigh-in-motion because they reflect the relationship between the bridge responses and the loads on the bridge. However, in the traditional vehicle-based BIL/BIS calibration methods, the track width of the calibration vehicle was ignored, leading to the accuracies of the calibrated influence lines/surfaces being affected by the track width and the transverse unbalance of the calibration vehicle. To address this problem, a new method, which can eliminate the negative effects of the track width and transverse unbalance, is proposed in this study. It provides a more accurate solution for bridge influence lines/surfaces than the traditional methods. The obtained bridge influence line/surface offers a more accurate input for related technologies and applications such as the bridge weigh-in-motion techniques and therefore improves the accuracy of these related technologies. [ABSTRACT FROM AUTHOR]

Axle load data are an essential input for pavement design, yet for most North American agencies, there is uncertainty about the quality of axle load data obtained from weigh-in-motion (WIM) systems, the applicability of these data for pavement design, and potential opportunities to integrate axle load data from disparate sources. This article presents a novel and practical methodology to evaluate the quality of axle load data from WIM systems and roadside weigh scales through a series of hierarchical analyses designed to test data validity. When applied using data from Manitoba, Canada, the methodology quantified the uncertainty of axle loads measured at the weigh scales and piezo-quartz WIM, concluding that both could be used for pavement design applications. Data collected at piezo-polymer WIM sites exhibited poorer data validity; however, application of site-specific temperature correction factors significantly improved data validity at these sites. The article describes how other data quality dimensions, including spatial coverage, temporal coverage, and long-term data availability, could be considered when determining the suitability of disparate axle load data sources for pavement design. Application of the methodology enables a pragmatic evaluation of the quality and limitations of commonly-available axle load data, revealing uncertainties and data needs relevant for pavement design practice.

Simulating the stochastic traffic load has been an important issue for bridge condition evaluation. This paper proposes an improved cellular automaton for stochastic traffic load simulation with consideration of axle load and microscopic interaction. The cells, neighbors, transition rules and boundary conditions in the improved model are all redefined. The cell length can be manually defined with any value. The vehicle load can be precisely simulated using axle load if the cell length is set small or using concentrated load when a large cell length is defined. Acceleration based transition rules are proposed, and different acceleration for each vehicle can be computed to more reasonably simulate the microscopic behavior. The feasibility of the proposed model is validated through comparisons on traffic flow simulation and load effect quantification with in-field weigh in motion data and other models. The results indicate that the proposed model improves the existing models both in vehicle load simulation and traffic flow simulation and can be used for stochastic traffic load simulation for bridges with any length. [ABSTRACT FROM AUTHOR]

In India, the axle loads have increased substantially in the recent decades and a majority of such overloaded vehicles are expected to have increased tire pressure. Increased tire pressures have a significant impact on the performance of the pavement as the load is applied over a concentrated area. Very little data is available related to the magnitude of tire pressures currently observed in India and its impact on the rutting (Nr) and fatigue (Nf) life of bituminous pavements. This study aims at quantifying such information for India. A field survey was conducted at five weighbridges for 100 vehicles to measure the tire pressures and the corresponding axle loads. Considering all the rear axles, it was observed that the mean tire pressure was 833 kPa and about 50% of the vehicles operated with a tire pressure greater than 800 kPa. To illustrate the combined influence of axle load and tire pressure, pavement sections available in IRC: 37-2018 were chosen and evaluated for their rutting and fatigue performance. For instance, for 10% CBR and 50 Million Standard Axles (MSA) traffic, when the tire pressure was increased from 500 kPa to 1200 kPa, it was observed that Nf reduced by 41% and Nr reduced by 5%. The fatigue life of the surface layer is seen to be more sensitive to variation in tire pressure. Moreover, the magnitude of influence exerted by the tire pressure depended on the axle load to a large extent. [ABSTRACT FROM AUTHOR]

In the present paper, a new analog filter is proposed to check with high accuracy the axle load and gross vehicle weight of commercial vehicles moving at normal speed without disruption of traffic flow and ensure their respect to the transport regulation. The proposed technique is based on the zero crossing detector, designed as the basis component of the new analog filter which significantly decreases the range of measured errors according to the international standard. The promising results prove the effectiveness and the reliability of the filter under study. The intended accuracy is achieved since the maximum weighting error is less than 1% for the vehicle axles whereas the gross vehicle weight is less than 0.3% for a speed range of 40-100 km/h.

The center of gravity of a vehicle (CG) is a critical parameter in influencing the quality of driveability and safety, such as for preventing rollover accidents. Therefore, it is important to identify a vehicle’s CG in practical situations. In particular, it is strongly desired to make it possible to measure the height of the CG of trucks and trailers freighted with various voluminous and heavy loads on business operation. The technology of Weigh-In-Motion (WIM) is being developed to identify the gross weight of trucks and trailers and detect overload. In this paper, the authors propose a method for the estimation of a vehicle’s CG, especially the height of CG, based on the WIM system. The basic theory is described at first, and the validity is shown by means of basic experiments using a light truck and a motorbike.

In 2013, Finland introduced legislation increasing gross vehicle weights (GVW) on a number of trucks. Since the actual impact on road damage is nearly impossible to quantify in advance, the present analysis of road surface measurements is intended to provide knowledge regarding the impact on road damage. Rutting is influenced by many conflated phenomena. To indicate and capture the effect on road damage due to the new maximum GVW for certain truck- and trailer combinations, the analysis follows two different but mutually supporting lines of reasoning, empirical and theoretical, respectively. Analysis of measured rut depth is supported by theoretical calculations. Theoretical findings clearly indicate that the relative increase in road damage induced by higher GVW is larger than the increase in relative payload capacity. There was a rapid fleet shift towards heavier trucks after 2013, and statistical (empirical) analysis of road surface measurements shows an increase in rutting after this introduction. [ABSTRACT FROM AUTHOR]

In this study, we aimed to determine the reliability of estimating the specific fuel consumption by using ANN instead of long and costly testing approaches. For this purpose, specific fuel consumption was determined at different axle loads, tire pressures and drawbar forces for a 60 HP tractor. In addition, the results were also estimated with the help of Artificial Neural Networks, which is one of the machine learning methods. The tests were carried out on the Tractor Draft Test Track. In the study, three different drive tire inner pressures (160 kPa, 120 kPa and 80 kPa), four different dynamic axle loads (1796 daN, 2076 daN, 2276 daN, 2476 daN) with adding extra loads and four different traction forces (500 daN, 1000 daN, 1500 daN, 2000 daN) were tested for their effects on specific fuel consumption. Specific fuel consumption values varied between 290.7-542.1 g/kWh depending on the draft force in the tests. Despite the 38% increase in the axle load, a 3.5% decrease occurred in the specific fuel consumption values. Specific fuel consumption values increased when tire inner pressure increased. Specific fuel consumption increased by 1.03% when a 100% increase in tire pressure was realized. In ANN, the most successful model was determined by trying different training algorithms, transfer functions and the number of neurons in the hidden layer. In the most successful network model, MAE, RMSE values for the prediction of specific fuel consumption were found to be 0.005331,0.007551 respectively. [ABSTRACT FROM AUTHOR]

Occurrence of top down and bottom up fatigue cracking in asphaltic pavements is common. Conventional pavement analysis methods ignore the existence of cracks in asphaltic layers. However, it seems that the responses of cracked pavement would not be the same as a pavement without crack. This paper describes effects of crack type, position and length, and vehicles tire inflation pressure and axle load on the performance of cracked asphalt pavement. Tensile strain at the bottom of asphaltic layer, the vertical strain on subgrade, maximum deflection on the surface, rut depth and the stress intensity factors of cracked pavement, with top down and bottom up crack have been computed using 3D Finite Elements method in ABAQUS. Moving load of standard single axle with different loads and tire pressures have been used in the analysis. Standard 8.2 ton single axle load at different tire pressures of 552(80), 690(100), 828(120) and 1035(150) kPa(psi) and single axle at different loads of 5, 8.2 and 15 ton, all at the same tire pressure of 690 kPa, have been used. Results show that the pavement responses increase with increasing tire pressure and axle load with higher values and rate of increase with increasing tire pressure and axle load for the cracked pavement compared with the pavement without crack. For the pavement structure investigated in this study, it was found that, in general, top down crack results in higher responses than bottom up crack.

The influence of the cargo weight loaded on the vehicle and the total gross mass of the vehicle on the braking characteristics is often researched from the road safety reason. However, there is not enough knowledge about the influence of weight and load distribution on the loading area of small trucks or vans on their braking characteristics. This article presents the results of measurements of braking decelerations of the van of N1 category and the braking characteristics of a vehicle loaded with different cargo mass with different cargo locations on the loading area. The impact of the longitudinal cargo position on the loading area on the load of the individual axles and thus on the braking deceleration of the vehicle was investigated. The influence of the height of the center of gravity on the dynamic axle load during braking was also determined. Method of direct vehicle deceleration measurement was used by a decelerometer. There were calculated cargo weight and cargo position influences on the dynamic axle load during braking according to the vehicle deceleration.

Whitetopping technique for rehabilitation of bituminous pavements has been considered as a cost-effective solution when the life cycle cost of pavement is considered. Thin whitetopping is a preferred overlay when both the structural and functional capacities of the pavement are required to be enhanced. IRC:SP:76-2015 outlines the procedure for construction of thin whitetopping in India. While IRC:SP:76-2015 suggests that thin whitetopping can be used on rural roads and medium to moderately heavy volume roads, the traffic composition related to the same is not clearly specified. In this study, an attempt was made to specify the limiting traffic characteristics for thin whitetoppings in terms of the axle load and their number of repetitions. To estimate the effect of traffic, the actual traffic data collected from four National Highways in India were used and the whitetopping design was carried out as per IRC:SP:76-2015. To increase the total load carrying capacity of the whitetopping overlay, especially in locations experiencing heavier traffic loads, mixes with different dosages of polypropylene fibres were designed and silica fume was added to enhance the bond between fibres and concrete. Eight different mixes were prepared with different combinations of fibre dosage (0.8%, 1.3% and 1.8%) and silica fume (8% and 13%) in addition to a control mix and a mix with 8% silica fume and no fibres. The mix with 8% silica fume and 1.8% fibres exhibited the highest equivalent flexural strength and the control mix with no fibres and silica fume exhibited the lowest equivalent flexural strength. These two mixes were considered to estimate the effect of axle loads. In most cases, it was seen that thin whitetopping without fibres failed in design for the actual traffic conditions as the fatigue response was highly sensitive to the axle loads. When the axle loads were limited closer to the legal axle loads specified in IRC:3-1983, it was seen that even the mix without fibres was able to sustain the design traffic. [ABSTRACT FROM AUTHOR]

Purpose. The research is aimed at determining changes in the state of the geometrical parameters of the railway track, depending on the passing tonnage in dynamic interaction with the 25 tf/axle load rolling stock. Methodology. For data acquisition, the authors carried out a statistical analysis of the indicators of digital measurements of the track condition by KVL-P track-measuring cars. Using the program of calculating the mean-square deviation of the geometric parameters of the track, the deviation of the track parameters within the test sections was estimated. Findings. During the observation period it was found that on average the intensity of track strain accumulation increases. However, according to the results of the factor dispersion analysis with 0.95 probability, it is impossible to unequivocally state the impact of the factor of using the cars with an axial load of up to 25 tf/axle on the deterioration of the track condition parameters. Herewith it should be noted that the share of cargo carried in the cars with axial load of up to 25 tf/axle during the observation period was less than one per cent. According to the values of the mean-square deviation, the state of the geometrical parameters of the track and their predicted changes were estimated, which showed that the increased axial load will lead to decreased life of the rails, which are the most expensive elements of the track structure, shortened service life of the railroad switches and increased labor costs for workers involved in track repair and maintenance. The corresponding reduction of inter-repair periods, which corresponds to the standards, is projected. In order for heavy-duty wagons not to destroy the infrastructure, there must be at least two limitations: by the types of goods transported and by the speed of movement. Originality. The authors conducted a study to assess the impact of cars with 25 tf/axle load on the state of the geometric parameters of the railway track and proposed solutions to the issue of introducing the 25 tf/axle load rolling stock in Ukraine. Practical value. On the basis of the obtained results it is possible to estimate the impact of the axial load on the intensity of the track condition changes and to predict the reduction of inter-repair periods in connection with the track deterioration and in accordance with the train speed restriction.

Static weight estimation of a vehicle in motion is challenging, especially when the vehicle is accelerating and decelerating. This paper presents a new estimation method for accelerating and decelerating vehicles. This method uses at least two miniature load measurement devices cascaded in traffic lane and consideration of transfer load between the front and rear wheels of a motorbike. Both individual axle load and the gross mass of the motorbike are estimated with accuracy under field conditions.

Accurately and reliably measuring the gross weight and static load of the axles of moving vehicles, especially trucks, is important for preventing road damage and improving traffic safety and monitoring efficiency. This type of vehicle weight measurement is called “weigh-in-motion” (WIM). The conventional purpose of WIM is solely the estimation of the vehicle gross weight. However, WIM is also valuable for estimating the static axle load and the height of the vehicle’s center of gravity, and possibly additional measurements. In this study, a method based on the averaging principle is proposed for signal processing in WIM systems. A preliminary experimental investigation, which involved two types of motorbikes and a light truck as test vehicles, and miniature plate-type measurement devices built by the authors, is presented. The gross weight and the static load of each axle of the vehicles, which traveled at various speeds up to approximately 40 km/h, are estimated with high accuracy.

This study presents the structural responses of flexible pavement which were subjected to different axle group loads. Three types of axle group loads, e.g. single axle-dual wheel, tandem axle-dual wheel, and tridem axle-dual wheel, were applied over the field for the instrumented trial section. The corresponding structural responses were measured using a series of embedded instrumentations e.g. pressure cells, asphalt strain gauges, strain gauges, thermocouples, moisture sensors etc. A 3-dimensional (3-D) finite-element analysis (FEA) model and the multi-layer linear-elastic analysis (LEA) were developed to estimate structural responses which were then compared with the field measurement data. Both FEA and LEA assumed the pavement layer materials to be homogeneous, isotropic, and linearelastic. The elastic moduli of pavement layers were determined from the falling weight deflectometer (FWD) based on the backcalculation procedure. Results from the analysis indicated that both FEA and LEA were in good agreement with the field measurement results with some exceptions for strains under the asphalt concrete surface. [ABSTRACT FROM AUTHOR]

In Nigeria, goods haulage is currently dominated through heavy trucks, whose effect on the pavement deterioration can be enormous, because the truck wheel/pavement interaction plays a key role in deterioration of pavement life. This study aims to measure the truck wheel/pavement contact characteristics with a view to develop its quantitative damaging influence on a pavement structure. Axle load distribution, tyre inflation pressure and tyre/pavement contact area of selected tyre types for different axle configurations were determined for four classes of trucks being used by a major haulage outfit in Nigeria, Messrs Dangote Industries Limited. The results obtained showed that the tyre pavement contact length depends on tyre load as the length increases with increase in tyre load, while tyre pavement contact width is averagely constant with tyre load increase. It is concluded that design and use of tyres should allow for large contact areas with small tyre pressures to lessen the menace of pavement deterioration, and also there is need for a strict control for standards of truck loads that travel on Nigerian road.

The objective of this work was to evaluate the effect of repeated traffic with a light-weight tractor on the physical/mechanical properties of an Aridisol soil from eastern Almería (Spain). The soil has been used for almond (Prunus amigdalus L.) production for the past 29 years. A light modal tractor (≈15 kN overall load) and different traffic frequencies or treatments; namely, 0 (control, no traffic), and 1, 5, 7, and 10 passes, respectively, were used. The following variables were measured: cone Index (CI); bulk density (BD); total soil porosity (TSP); water infiltration into soil (I), and ruth depth (RD). The results showed that, only treatments 7 and 10 led to significant increases in CI and BD throughout the soil profile (0-450 mm). Changes in TSP in those treatments were consistent with changes in soil bulk density. No significant differences in RD were found when the tractor passed 1 or 5 times. All traffic treatments resulted in significant compaction in the topsoil layer (0-150 mm) and soil physical conditions that would be regarded as unsuitable for establishment of most arable crops.

Soil compaction has detrimental effects on the physical, mechanical and hydraulic properties of soils, and affects important soil processes and function, and crop productivity. This work was conducted to investigate soil compaction impacts in integrated arable croppinglivestock systems managed under conventional tillage (CT) and no-tillage (NT). The work examined the combined effects of cattle trampling and farm machinery traffic on: soil strength, soil deformation, and water infiltration into soil. The following treatments were applied to soil (Entic Haplustoll, 60% sand) managed under CT and NT: three traffic intensities (1, 5, 7 passes) performed with light (2WD, 53 kN) and heavy (4WD, 100.4 kN) tractors, and two stocking densities (400 and 700 kg ha-1), respectively. Controls were also used to represent the condition of the soil without any effect of livestock or field traffic. In both tillage systems, soil penetration resistance (strength) increased and water infiltration into soil decreased as traffic intensities or stocking rates applied increased. There was a significant traffic intensity × stocking rate interaction, which influenced the depth and extent of soil compaction at depth. Despite these results, stubble grazing during fallow should not be discouraged as this practice offers mixed farming systems several agronomic and financial benefits. If stubble was to be grazed, the system would need to be carefully managed: (1) avoid 'random' traffic using permanent or semipermanent traffic paths to minimise the field wheeled area, (2) vacate livestock from the field, or confine it to a sacrificial area, when the soil water content exceeds a critical level above which soil damage is likely, and (3) maintain more than 60%-70% ground cover. Tillage repair treatments can be targeted to those sacrificial or 'hot-spots' areas so that localised, as supposed to widespread, compaction problems are rectified before the next crop is established. [ABSTRACT FROM AUTHOR]

Increasing the axle load causes track deterioration and permanent settlement of the ballast layer. In the ballasted railway tracks, due to the inevitability of unequal settlements in the ballast layer, part of the rail due to high flexural rigidity will become suspended, which causes the formation of the track with unsupported and partially supported sleepers. This situation increases rail vertical displacement and reactions on adjacent sleepers. Several models have been presented to study the effect of unsupported sleepers on dynamic responses of train-track interaction. In this paper, by applying mathematical model, unsupported and partially supported sleepers have been modeled and equations of motions for train-track interaction were written by assuming nonlinear behavior of rail and wheel contact. Following by solving the equations via numerical integration in the time domain, the effect of axle load and pad stiffness on rail vertical displacement were investigated. Results of the analysis suggested that through increasing the axle load rail displacement increased by 13 % in the unsupported sleeper and from 5 to 10 % in the partially supported sleeper. Also, by increasing the pad stiffness rail displacement decreased from 2 to 13 % in the unsupported sleeper and from 1 to 6 % in the partially supported sleeper. [ABSTRACT FROM AUTHOR]

In Nigeria, goods haulage is currently dominated through heavy trucks, whose effect on the pavement deterioration can be enormous, because the truck wheel/pavement interaction plays a key role in deterioration of pavement life. This study aims to measure the truck wheel/pavement contact characteristics with a view to develop its quantitative damaging influence on a pavement structure. Axle load distribution, tyre inflation pressure and tyre/pavement contact area of selected tyre types for different axle configurations were determined for four classes of trucks being used by a major haulage outfit in Nigeria, Messrs Dangote Industries Limited. The results obtained showed that the tyre pavement contact length depends on tyre load as the length increases with increase in tyre load, while tyre pavement contact width is averagely constant with tyre load increase. It is concluded that design and use of tyres should allow for large contact areas with small tyre pressures to lessen the menace of pavement deterioration, and also there is need for a strict control for standards of truck loads that travel on Nigerian road. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)