外文文献翻译
乳头肥大(含：英文原文及中文译文)
文献出处：Y Hassan. Geometric Design of Highways[J] Advances in Transportation Studies, 2016, 6(1):31-41.
英文原文
Geometric Design of Highways
Y Hassan
A. Alignment Design
The alignment of a road is shown on the plane view and is a ries of straight lines called tangents connected by circular curves. In modern practice it is common to interpo transition or spiral curves between tangents and circular curves.
The line shape should be continuous, sudden changes from flat line to small radius curve or sudden
change of long line end connected to small radius curve should be avoided, otherwi a traffic accident may occur. Similarly, arcs with different radii end-to-end (complex curves) or short straight lines between two arcs with different radii are bad lines unless an easing curve is inrted between arcs. The long, smooth curve is always a good line becau it is beautifully lined and will not be abandoned in the future. However, it is not ideal that the two-way road line shape is compod entirely of curves, becau some drivers always hesitate to pass through curved road gments. The long and slow curve is ud in the
smaller corners. If you u a short curve, you will e "kinks." In addition, the design of the flat and vertical ctions of the line should be considered comprehensively and should not be only one. No matter which, for example, when the starting point of the flat curve is near the vertex of the vertical curve, rious traffic accidents will occur.
保健油>墨西哥风情V ehicles driving on curved ctions are subjected to centrifugal force, and they need a force of the same magnitude in the opposite direction due to the height and lateral friction to offt it. From the viewpoint of highway design, the high or horizontal friction cannot exceed a certain value. The maximum, the control values for a certain design speed may limit the curvature of the curve. In general, the curvature of a circular curve is reprented by its radius. For the linear design, the curva
乐于助人的名言ture is often described by the curvature, ie, the central angle corresponding to the 100-foot curve, which is inverly proportional to the radius of the curve.
A normal road arch is t in a straight ction of the road, and the curve ction is t to a super high, and an excessively gradual road ction must be t between the normal ction and the super high ction. The usual practice is to maintain the design elevation of each midline of the road unchanged. By raising the outer edge and lowering the inner edge to form a super high, for the line shape where the straight line is directly connected with the circle curve, the super high should never start on the straight line before reaching the curve. At the other end of the curve at a
certain distance to reach all the ultra-high.
If the vehicle is driving at a high speed on a restricted ction of road, such as a straight line connected with a small radius circle curve, driving will be extremely uncomfortable. When the car enters the curve ction, the super high starts and the vehicle tilts inward, but the pasnger must maintain the body becau it is not subjected to centrifugal force at this time. When the car reaches the curve ction, centrifugal force suddenly occurs, forcing pasngers to make further posture adjustments. When the car leaves the curve, the above process is just the opposite. After inrting th极品公子3
e relaxation curve, the radius gradually transitions from infinity to a certain fixed value on the circle curve, the centrifugal force gradually increas, and ultra-high levels are carefully t along the relaxation curve, and the centrifugal force is gradually incread, thereby avoiding driving bumps.
The eament curve has been ud on railways for many years, but it has recently been applied on highways. This is understandable. The train must follow a preci orbit, and the uncomfortable feeling mentioned above can only be eliminated after the ea curve is ud. However, the driver of a car can change the lateral position on the road at will, and he can provide a relaxation curve for himlf by making a roundabout curve. But doing this in one lane (sometimes in other lanes) is very dangerous. A well-designed relaxation curve makes the above roundaboutness
音的笔顺笔画顺序unnecessary. Multi-cluster safety is a measure, and roads are widely ud as transition curves.
For a circular curve with the same radius, adding an easing curve at the end will change the relative positions of the curve and the straight line. Therefore, whether or not to u an easing curve should be determined before final alignment survey. The starting point of the general curve is labeled PC or BC and the end point is labeled PT or EC. For curves with transition curves, the usual marker configurations are: TC, SC, CS, and ST.
聊斋志异之阿宝
For two-way roads, the road width should be incread at sharp bends. This is mainly bad on the following factors: 1. The driver is afraid to get out of the edge of the road. 2. Due to the difference in the driving trajectory of the front and rear wheels of the vehicle, the effective lateral width of the vehicle increas; 3. The width of the front of the vehicle that is inclined relative to the centerline of the road. For roads that are 24 feet wide, the added width is negligible. Only if the design speed is 30 mil / h and the curvature is up to 2 ft. However, for narrow roads, widening is very important even on smooth curve ctions. The recommended widening values and widened designs are shown in ". Highway linear design."
B. Longitudinal slope line
The vertical alignment of the highway and its impact on the safety and精彩绝伦的意思
economy of vehicle operation constitute one of the most important elements in highway design. V ertical lines consist of straight lines and vertical parabolas or circular lines called vertical slope lines. When a grade line ris gradually from a horizontal line, it is called an uphill, and vice versa, it is called a downhill slope. In the analysis of slope and slope control, designers usually have to study the effect of changes in slope on the midline profile. In determining the slope, the ideal situation is th
e balance of excavation and filling, and there is no large amount of borrowers and abandoned parties. All the earth moving is carried down as far as possible and the distance is not long. The slope should change with the terrain and be consistent with the direction of ascent and descent of the existing drainage system. In the mountains, the slopes should be balanced to minimize the total cost. In the plain or grassland areas, the slope is approximately parallel to the surface, but higher than the surface at a sufficient height to facilitate drainage of the surface. If necessary, winds can be ud to remove surface snow. If the road is approaching or running along a river, the current height of the slope is determined by the expected flood level. In any ca, the gentle slope should be t at the excavation ction compared to the short vertical ction connecting the short vertical curve due to the upslope downslope, and the ction from the downslope upslope should be t at the fill. Road ction. Such a good linear design can often avoid the formation of a mound or depression
