L3Geometricdesignofhighways公路线型设计

1、刘克瑾河南工业大学土木建筑学院土木工程专业英语lesson 3 geometric design of highwaysvtext a alignment designvalignment lanm()nt n. 队列，线形；v课文a 线路设计vtext b gradesv课文b 坡度vtext c sight distance v课文c 视距geometric ,dmetrk adj. 几何学的v1/9 the alignment of a road is shown on the plane view and is a series of straight lines called tan

2、gents connected by circular curves. in modern practice it is common to interpose transition or spiral curves between tangents and circular curves.vtangent tn(d)()nt n. 数 切线，数 正切 adj. 切线的，相切的；vinterpose ntpz vi. 干预；插入；vtransition trnz()n; trn-; -s- n. 过渡；转变；vcircular skjl adj. 循环的；圆形的；vspiral spar()l

3、 n. 螺旋；旋涡；螺旋形之物 adj. 螺旋形的；盘旋的 vt. 使成螺旋形；使作螺旋形上升 vi. 盘旋；成螺旋形；螺旋形上升（过去式spiraled/spiralled，过去分词spiraled/spiralled，现在分词spiraling/spiralling，第三人称单数spirals，副词spirally）vspiral curve 螺旋曲线vcircular curve 圆形曲线v1/9 the alignment of a road is shown on the plane view and is a series of straight lines called tang

4、ents connected by circular curves.v in modern practice it is common to interpose transition or spiral curves between tangents and circular curves.v翻译？v1 /9 the alignment of a road is shown on the plane view and is a series of straight lines called tangents connected by circular curves. v翻译v公路的线路显示在平

5、面图上，是一系列由圆曲线连接的切线而成。vin modern practice it is common to interpose transition or spiral curves between tangents and circular curves. v翻译v在现代实践（做法）中，在切线和圆曲线之间插入过渡线（螺旋线）是常见做法。v2 /9 alignment must be consistent. sudden changes from flat to sharp curves and long tangents followed by sharp curves must be

6、avoided; otherwise, accident hazards will be created. likewise, placing circular curves of different radii end to end ( compound curves ) or having a short tangent between two curves is poor practice unless suitable transitions between them are provided. long, flat curves are preferable at all times

7、, as they are pleasing in appearance and decrease possibility of future obsolescence. however, alignment without tangent is undesirable on two-lane roads because some drivers hesitate to pass on curves. long, flat curves should be used for small changes in direction, as short curves appear as kink.

8、also horizontal and vertical alignment must be considered together, not separately. for example, a sharp horizontal curve beginning near a crest can create a serious accident hazard. v2 -1/9 valignment must be consistent. sudden changes from flat to sharp curves and long tangents followed by sharp c

9、urves must be avoided; otherwise, accident hazards will be created. likewise, placing circular curves of different radii end to end ( compound curves ) or having a short tangent between two curves is poor practice unless suitable transitions between them are provided. vconsistent knsst()nt adj. 连续的连

10、续的vradii reda n. 半径（radius的复数）vcompound curve 复合曲线vsharp curve 急弯曲线；锐曲线；急弯；小半径曲线vtransitiontrnzn n. 过渡；转变v2 -2 /9 vlong, flat curves are preferable at all times, as they are pleasing in appearance and decrease possibility of future obsolescence. however, alignment without tangent is undesirable on t

11、wo-lane roads because some drivers hesitate to pass on curves. long, flat curves should be used for small changes in direction, as short curves appear as kink. also horizontal and vertical alignment must be considered together, not separately. for example, a sharp horizontal curve beginning near a c

12、rest can create a serious accident hazard. flat curve 平缓曲线；平滑曲线；大曲率曲线preferable pr frbl adj. 更好的，更可取的；更胜一筹的pleasing pli:zi adj. 令人愉快的；obsolescence ,bsulesns n. 废弃；undesirable ndzarb()l adj. 不良的；不受欢迎的；kink kk n. 扭结；蜷缩 vt. 使扭结 vi. 扭结v2 /9 alignment must be consistent. sudden changes from flat to sharp

13、 curves and long tangents followed by sharp curves must be avoided; otherwise, accident hazards will be created. likewise, placing circular curves of different radii end to end ( compound curves ) or having a short tangent between two curves is poor practice unless suitable transitions between them

14、are provided. long, flat curves are preferable at all times, as they are pleasing in appearance and decrease possibility of future obsolescence. however, alignment without tangent is undesirable on two-lane roads because some drivers hesitate to pass on curves. long, flat curves should be used for s

15、mall changes in direction, as short curves appear as kink. also horizontal and vertical alignment must be considered together, not separately. for example, a sharp horizontal curve beginning near a crest can create a serious accident hazard. v3 /9 a vehicle traveling in a curved path is subject to c

16、entrifugal force. this is balanced by an equal and opposite force developed through superelevation and side friction. from a highway design standpoint, both superelevation and side friction cannot exceed certain maximums, and these controls place limits on the sharpness of curves that can be used wi

17、th a design speed.v3 /9 a vehicle traveling in a curved path is subject to centrifugal force. this is balanced by an equal and opposite force developed through superelevation and side friction. from a highway design standpoint, both superelevation and side friction cannot exceed certain maximums, an

18、d these controls place limits on the sharpness of curves that can be used with a design speed.centrifugal ,sentrfjug()l; sentrfjg()l n. 离心机； adj. 离心的；centrifugal force 离心力side friction 横向摩擦superelevation ,sju:p,elivein n. （铁路或公路的）超高; 弯面倾斜度;道路弯面加倾度超高超高 （ superelevationsuperelevation ） 公路平曲线路段，为抵销离心力，

19、提高外侧路面之高度standpoint stn(d)pnt n. 立场；观点sharpness :pnis n. 锐利；锐度design speed 设计速度v4 /9 vusually the sharpness of a given circular curve is indicated by its radius. however, for alignment design, sharpness is commonly expressed in terms of degree of curve, which is the central angle subtended by a 100-

20、ft length of curve. degree of curve is inversely proportional to the radius.v4 /9 vusually the sharpness of a given circular curve is indicated by its radius. however, for alignment design, sharpness is commonly expressed in terms of degree of curve, which is the central angle a 100-ft length of cur

21、ve. degree of curve is inversely proportional to the radius.vindicated nd,ketd v. 表明（indicate的过去分词）；指出；显示vradius reds n. 半径，半径范围；vin terms of 依据；根据；用；按照；在方面；以措词vdegree of curve, 曲率vsubtend sbtend vt. （弦、边）对（弧、角）；对向vft-foot, 英尺1ft=12in=0.3048mv5 /9 vtangent sections of highways carry normal cross slo

22、pe; curved sections are superelevated. provision must be made for gradual change from one to the other. this usually involves maintaining the center line of each individual roadway at profile grade while raising the outer edge and lowering the inner edge to produce the desired superelevation. where

23、the alignment consists of tangents connected by circular curves, introduction of superelevation is begun on tangent before the curve is reached, and full superelevation is attained some distance beyond the point of curve.vtangent section 切线段vcurved section 曲线段vcross slope 横坡；横向坡度vprofile grade 纵断面坡度

24、vprovision prv()n n. 事先准备；防备（未来的需要）vintroduction of 引进；引入vattained vt. 取得，得到，获得（attain的过去式）vpoint of curve 曲线起点 ;曲线始点v5 /9 vtangent sections of highways carry normal cross slope; curved sections are superelevated. provision must be made for gradual change from one to the other. vthis usually involve

25、s maintaining the center line of each individual roadway at profile grade while raising the outer edge and lowering the inner edge to produce the desired superelevation. vwhere the alignment consists of tangents connected by circular curves, introduction of superelevation is begun on tangent before

26、the curve is reached, and full superelevation is attained some distance beyond the point of curve.v6-1 /9 if a vehicle travels at high speed on a carefully restricted path made up of tangents connected by sharp circular curve, riding is extremely uncomfortable. as the car approaches a curve, superel

27、evation begins and the vehicle is tilted inward, but the passenger must remain vertical since there is no centrifugal force requiring compensation. when the vehicle reaches the curve, full centrifugal force develops at once, and pulls the rider outward from his vertical position. to achieve a positi

28、on of equilibrium he must force his body far inward. as the remaining superelevation takes effect, further adjustment in position is required. this process is repeated in reverse order as the vehicle leaves the curve. when easement curves are introduced, the change in radius from infinity on the tan

29、gent to that of the circular curve is effected gradually so that centrifugalv6-2 /9 force also develops gradually. by careful application of superelevation along the spiral, a smooth and gradual application of centrifugal force can be had and the roughness (can be) avoided.approach prt n. 方法；途径；接近 ;

30、 vt. 接近； vi. 靠近tilt tlt n. 倾斜 vt. 使倾斜；使翘起 vi. 倾斜；翘起take effect 生效；起作用easement izm()nt n. 缓和；减轻easement curve 缓和曲线far f adj. 远的；久远的 adv. 很；遥远地；到很远的距离；到很深的程度 n. 远方v6-1 /9v if a vehicle travels at high speed on a carefully restricted path made up of tangents connected by sharp circular curve, riding is

31、 extremely uncomfortable. vas the car approaches a curve, superelevation begins and the vehicle is tilted inward, but the passenger must remain vertical since there is no centrifugal force requiring compensation. vwhen the vehicle reaches the curve, full centrifugal force develops at once, and pulls

32、 the rider outward from his vertical position. to achieve a position of equilibrium he must force his body far inward. vas the remaining superelevation takes effect, further adjustment in position is required. v6-2 /9 vthis process is repeated in reverse order as the vehicle leaves the curve. vwhen

33、easement curves are introduced, the change in radius from infinity on the tangent to that of the circular curve is effected gradually so that centrifugal force also develops gradually. vby careful application of superelevation along the spiral, a smooth and gradual application of centrifugal force c

34、an be had and the roughness ( can be ) avoided.approach prt n. 方法；途径；接近 vt. 接近；着手处理 vi. 靠近tilt tlt n. 倾斜 vt. 使倾斜；使翘起 vi. 倾斜；翘起take effect 生效；起作用easement izm()nt n. 缓和；减轻easement curve 缓和曲线v7 /9 veasement curves have been used by the railroads for many years, but their adoption by highway agencies ha

35、s become only recently. this is understandable. railroad trains must follow the precise alignment of the tracks, and the discomfort described here can be avoided only by adopting easement curves. on the other hand, the motor-vehicle operator is free to alter his lateral position on the road and can

36、provide his own easement curves by steering into circular curves gradually. however, this weaving within a traffic lane ( but sometimes into other lane ) is dangerous. properly designed easement curves make weaving unnecessary. it is largely for safety reasons, then , that easement curves have been

37、widely adopted by highway agencies.vrailroads n. 铁路（railroad的复数）；铁路部门vhighway agency 公路管理局agency n. 机构vsteering str n. 操纵；指导；掌舵 v. 驾驶；掌舵（steer的ing形式）vweave wiv vi. 迂回行进 vt. 使迂回前进vtraffic lane 行车道；通车车道v7 /9 veasement curves have been used by the railroads for many years, but their adoption by highway

38、 agencies has become only recently.v this is understandable. railroad trains must follow the precise alignment of the tracks, and the discomfort described here can be avoided only by adopting easement curves. von the other hand, the motor-vehicle operator is free to alter his lateral position on the

39、 road and can provide his own easement curves by steering into circular curves gradually. vhowever, this weaving within a traffic lane ( but sometimes into other lane ) is dangerous. properly designed easement curves make weaving unnecessary. vit is largely for safety reasons, then , that easement c

40、urves have been widely adopted by highway agencies.v8 /9 vfor the same radius circular curve, the addition of easement curves at the ends changes the location of the curve with relation to its tangents; hence the decision regarding their use should be made before the final location survey. the point

41、 of beginning of an ordinary circular curve is usually labeled the pc ( point of curve ) or bc ( beginning of curve). its end is marked the pt ( point of tangent ) or ec ( end of curve ). for curves that include easements, the common notation is, as stationing increases: ts ( tangent to spiral ), sc

42、 ( spiral to circular curve ), cs ( circular curve to spiral ), and st ( spiral to tangent ).v8/9 vfor the same radius circular curve, the addition of easement curves at the ends changes the location of the curve with relation to its tangents; hence the decision regarding their use should be made be

43、fore the final location survey. vthe point of beginning of an ordinary circular curve is usually labeled the pc ( point of curve ) or bc ( beginning of curve). its end is marked the pt ( point of tangent ) or ec ( end of curve ). vfor curves that include easements, the common notation is, as station

44、ing increases: ts ( tangent to spiral ), sc ( spiral to circular curve ), cs ( circular curve to spiral ), and st ( spiral to tangent ).label leb()l n. 标签；vt. 标注；贴标签于notation nte()n n. 符号；stationing n. 驻军 v. 驻扎（station的ing形式）;布点; 定位v9/9 von two-lane pavements provision of a wilder roadway is advisab

45、le on sharp curves. this will allow for such factors as (1) the tendency for drivers to shy away from the pavement edge, (2) increased effective transverse vehicle width because the front and rear wheels do not track, and (3) added width because of the slanted position of the front of the vehicle to

46、 the roadway centerline. for 24-ft roadways, the added width is so small that it can be neglected. only for 30mph design speeds and curves sharper than 22(degree) does the added width reach 2 ft. for narrower pavements, however, widening assumes importance even on fairly flat curves. recommended amo

47、unts of and procedures for curve widening are given in geometric design for highways.vprovisionprovision prv()n n. 事前准备vadvisable dvazb()l adj. 明智的，可取的，适当的vshy away from 回避，退缩；躲避；vtransverse trnzvs; trnz-; -ns- n. 横断面；贯轴；adj. 横向的；横断的；贯轴的vrear wheel 后轮；后车轮vvehicle width 车宽vtrack trk vi. 追踪；vt. 追踪；通过；

48、循路而行；n. 轨道；足迹，踪迹；小道vslanted sl:ntid, slnt- adj. 斜的；有倾向的 v. 使倾斜（slant的过去式和过去分词）vmph ,em pi: eit abbr. 每小时英里数（miles per hour）vassume sjum vt. 承担；假定；采取；v9 /9 von two-lane pavements provision of a wilder roadway is advisable on sharp curves.v this will allow for such factors as (1) the tendency for driv

49、ers to shy away from the pavement edge, (2) increased effective transverse vehicle width because the front and rear wheels do not track, and (3) added width because of the slanted position of the front of the vehicle to the roadway centerline. vfor 24-ft roadways, the added width is so small that it

50、 can be neglected. only for 30mph design speeds and curves sharper than 22(degree) does the added width reach 2 ft. vfor narrower pavements, however, widening assumes importance even on fairly flat curves. recommended amounts of and procedures for curve widening are given in geometric design for hig

51、hways.vfinish lesson 3 geometric design of highways vtext a alignment designvalignment lanm()nt n. 队列，线形；v课文a 路线设计vtext b gradesv课文b 坡度vtext c sight distancev课文c 视距v1/9 vthe vertical alignment of the roadway and its effect on the safe and economical operation of the motor vehicle constitute one of t

52、he most important features of road design. the vertical alignment, which consists of a series of straight lines connected by vertical parabolic or circular curves, is known as the “grade line”. when the grade line is increasing from the horizontal it is known as a “plus grade”, and when it is decrea

53、sing from the horizontal it is known as a “minus grade”. in analyzing grade and grade controls, the designer usually studies the effect of change in grade on the centerline profile.vnew words and expressionsvgrade 坡度grade control 坡度控制grade line 坡度线，纵坡线grade length 坡长grade reductionminus grade 下坡 降坡p

54、lus grade 上坡 升坡maximum grade 最大纵坡minimum grade 最小纵坡sustained grade 持续坡度level grade 平坡steep grade 陡坡vparabolic ,prblk adj. 抛物线的parabolic curve 抛物线vchange in 在方面改变v1/9 vthe vertical alignment of the roadway and its effect on the safe and economical operation of the motor vehicle constitute one of the

55、most important features of road design.vthe vertical alignment, which consists of a series of straight lines connected by vertical parabolic or circular curves, is known as the “grade line”. vwhen the grade line is increasing from the horizontal it is known as a “plus grade”, and when it is decreasi

56、ng from the horizontal it is known as a “minus grade”.vin analyzing grade and grade controls, the designer usually studies the effect of change in grade on the centerline profile.v2/9vin the establishment of a grade, an ideal situation is one in which the cut is balanced against the fill without a g

57、reat deal of borrow or an excess of cut to be wasted. all hauls should be downhill if possible and not too long. the grade should follow the general terrain and rise and fall in the direction of the existing drainage. in mountainous country the grade may be set to balance excavation against embankme

58、nt as a clue toward least overall cost. in flat or prairie country it will be approximately parallel to the ground surface but sufficiently above it to allow surface drainage and, where necessary, to permit the wind to clear drifting snow. where the road approaches or follows along streams, the heig

59、ht of the grade line may be dictated by the expected level of flood water. under all conditions, smooth, flowing grade lines are preferable to choppy ones of many short straight sections connected with short vertical curves.vbalance against 和.保持平衡vhaul n. 搬运，运土，运程vterrain tren n. 地形，地势；领域；地带vin the

60、direction of 朝方向，向方向vmountainous mantns adj. 多山的；巨大的；山一般的vbe set to 被定在；被设为vtoward twd; twd; td prep. 向；对于；为了；接近；表示动作行为所向 adj. 即将来到的，进行中的voverall cost 总成本；全部成本；总值vprairie prer n. 大草原；牧场vwhere necessary 必要时；需要时；必要地方vdrifting snow 气象 低吹雪；飘雪；吹雪vunder all conditions 在所有条件下vpreferable to 更可取的，更好的vchoppy