《门路勘测设计》温习题(国外英文资料).doc

《道路勘测设计》复习题(国外英文资料) The basis of highway grade determination: road use task/function/traffic volume The design speed weather is good, the traffic density hour, the average driver can keep safe and comfortable the maximum speed. When driving on a flat curve, it produces slippage/tilt. When the lateral force is greater than the lateral force, the car will slip. The overturning moment caused by lateral force is larger than that of the vehicle. The longitudinal stability of the car is overthrown/longitudinal slip/longitudinal stability guarantee 1 / line/circle curve characteristics of easement curve linear straight line: short route home/shorten the mileage and car driving direction clear line-of-sight good/fast/driver of train operation is simple, the line is simple, easy to layout, good overtaking conditions. But a long straight line, mechanical driving drab, fatigue, also easy to overtake and speeding, the driver is difficult to estimate, form prone to glare at night round curve: any point of curvature radius r = constant, layout than easement curve is simple. When a certain speed, centrifugal force is constant, driving on plane curve to occupy the road width: poor visibility conditions. Larger radius circle QuXu linear beautiful/driving comfortable easement curve curvature gradient, in between the linear and circular curve, the linear meet when the car turning trajectory journey; Curvature gradient, make the road linear fit and beautiful, good visual effect and psychological effect, make the horizontal alignment is more flexible, linear degrees of freedom, can be compatible with terrain/object and the environment/coordination/cooperate, make the plane linear arrangement more flexible/economic/reasonable; Compared with the circle curve, the curve calculation and the measurement are complicated What is the mitigating curve, what is the function Easement curve refers to the linear and circular curve or radius of the large difference between the two to the same circle