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Fundamentals of Earthmoving
Published in John E. Schaufelberger, Giovanni C. Migliaccio, Construction Equipment Management, 2019
John E. Schaufelberger, Giovanni C. Migliaccio
Grade resistance is the force due to gravity that a piece of equipment must overcome when moving up a grade as illustrated in Figure 6.2. When the equipment moves down a grade, the force of gravity that assists movement is called grade assistance. Grades are usually described in terms of percent slope which is equal to the change in elevation divided by the horizontal distance times 100. For example, a slope that rises 5 feet per 100 feet would be a 5% slope.
Measures to Control Soil Erosion
Published in Abrar Yousuf, Manmohanjit Singh, Watershed Hydrology, Management and Modeling, 2019
Abrar Yousuf, Jonas Lenz, Eajaz Ahmad Dar
The four parameters which are taken into account to design the terrace cross section are: Batter slopeDimension of the shoulderInward slope of bench terrace and size of drainage channelOutward slope in case of terraces sloping outwards Batter slope: The batter slope is provided to impart stability to the fill material. The batter slope depends primarily on the soil material used for filling. The range of batter slope varies with the soil type. Flatter (or milder) the batter slope, larger is the area lost in terracing. The vertical cuts are used in very stable soils and when the depth of the cut is not more than 1m. Batter slope of 0.5:1 is used in loose and unstable soils.Dimension of shoulder bund: The shoulder of larger cross section is necessarily used in terraces sloping outwards and table top terraces in order to retain the runoff water within the terrace. In the case of inward sloping terraces, the size of the shoulder bund should be nominal. The shoulder bund also provides stability to the terraces.Inward and outward slope: The inward and outward slope of the bench terraces depends on the type of soil and average rainfall of the area. The inward slope may vary between 2 to 10%, whereas the outward slope varies between 2 to 8%. The size of the drainage channel is calculated on the basis of runoff rate to be disposed from the terrace area. The proper grade in the range of 0.5 to 1.0% is provided in the drainage channel.
Longitudinal-vertical dynamics of a high-speed train rescued by locomotives during braking on grades
Published in Vehicle System Dynamics, 2023
Lai Wei, Jing Zeng, Sheng Qu, Caihong Huang, Qunsheng Wang
The braking forces are provided by the locomotives, while the gravitational forces by cars on the grade. Since the maximum braking induced in-train force is located at the central connection section, this section is assumed to be in the grade change position. Therefore, the gravitational forces are only generated by the locomotives. Ignoring the resistance forces, the overall longitudinal force applied to the trainset is given in Equation (1). where, Fb is the braking force applied by the locomotives, m1 is the mass of one locomotive, n1 is the number of locomotives on the grade, is the track gradient. A positive sign corresponds to an ascending grade, while a negative to a descending grade.
Torsion and vertical curvature of motion-trajectory curves
Published in Mechanics Based Design of Structures and Machines, 2023
Concept of vertical curvature is widely used in railroad literature and is associated with track grade (Shabana 2021a). The grade is defined as the ratio (percentage) between vertical elevation and longitudinal distance along track segment. In railroad literature, vertical-development angle is related to vertical curvature by relationship where is always assumed constant, restricting vertical-development angle to linear variation or to constant value. These definitions play fundamental role in design and layout of railroad tracks, particularly when considering spiral section which connects two track sections which have different curvatures and different super-elevations. Figure 5 shows curve curvature horizontal curvature and vertical curvature Vertical-curvature results shown in this figure demonstrate that a spiral section can be designed such that this section remains planar and untwisted without need for assuming constant vertical curvature. This can be achieved by using assumption of zero torsion presented in this study.
Statistical analysis of geometric characteristics and speed reductions for raised pedestrian crosswalks (RPC)
Published in Journal of Transportation Safety & Security, 2020
Amir Mohammadipour, Alireza Mohammadipour, Seyed Hafez Alavi
Based on the above physical dimensions, the following parameters are obtained: Where, is the street grade, is the first ramp grade, and is the second ramp grade. Consistent with the convention in highway geometric design, a positive grade indicates an upgrade and a negative one a downgrade. In practice, is always positive (upward); and is always negative (downward). and are algebraic differences in grade in percent between the first ramp and the approach end of the road and between the leave end of the road and the second ramp, respectively. In addition, because the RPCs flat top crowns are horizontal, the absolute values of and are numerically equal to the absolute values of algebraic differences in grade at the two ends of the top flat crown. Therefore, the four variables A1, , , and are associated with the four consecutive sudden changes in vertical acceleration experienced by drivers traversing an RPC. Consequently, these variables are expected to affect the speeds on the RPCs.