下载掌阅APP，畅读海量书库
立即打开
Once the road authority has decided to construct a new major road， then it will employ either its own engineers or a consulting engineer to survey the alternative routes and carry out the road design.Information is required， for each of the possible routes， about the detailed ground levels of the terrain， which can now be obtained by aerial photography which is accurate to 6 inch. Details of the types of material for the construction of embankments， and of the geological strata， must be obtained from trial pits and bore holes taken along the line of the route and at bridge sites. The local climatic conditions， such as fog， frost and rain， must also be established. In developed countries，information is required about land values and various environmental factors which may need public enquiries.
From the survey information， the line and level of each of the possible roads will be chosen in accordance with the standards of gradient， sight lines and other factors laid down by the traffic authority. This should minimize the amount of material which has to be excavated and carried to“fill” the adjacent embankments. It is also important to keep the size of bridges needed to cross railways， rivers and other roads to a minimum. Taking into account these various factors， the choice of route is made and the design is carried out.
Arrangements are then made to purchase the land on which the road will run. Detailed drawings， specifications and bills of quantities are prepared so that constructors can tender， normally in competition with each other， for the construction of the work. The consulting engineer or highway authority will usually provide a resident engineer and site staff to ensure that the work is carried out successfully by the constructor in accordance with the drawings and specifications. Within the requirements of the design， the constructor will be responsible for deciding upon the methods of construction to be used.
When the construction team moves on to the site， it is first necessary to clear the line of the new road and fence it where animals may stray on to the works. Trees are cut down， stumps and rocks are grubbed up by bulldozer or where necessary， blasted out by explosives. It may also be necessary to build temporary haul roads ① and bridges or fords at the site of the river bridges.
The base of embankments and the slopes of cuttings must be protected from the action of ground water which could cause them to collapse. A primary drainage system is therefore constructed before starting earthworks along the length of the road to cut off the natural ground drainage， and prevent it from entering the works. This is usually done by digging a shallow cut-off ditch with a hydraulic excavator which has a shaped bucket. At the low point of the natural ground， the water flowing in these ditches is taken across the road line in piped or reinforced concrete culverts and allowed to flow away through the existing streams or ditches.
The topsoil is first stripped and stacked ready for spreading on the slopes of cuttings and embankments towards the end of construction. This work is usually done with catepillar tractors towing box scrapers. The main cutting and embankment work is then started， using rubber-tyred scrapers. These are single or twin-engined machines which have a horizontal blade that can be lowered to cut a slice of earth from the ground and collect this earth in the bowl of the scraper. When the scraper bowl is full—some machines can carry up to ② 50 cubic yards （38.2 m 3 ）—the blade is raised and the loaded scraper travels to the “ tip” area on the embankment. Particularly in hard digging， it is necessary for the scraper loading operation to be assisted by a pusher bulldozer which pushes the scraper while it is loading to speed up the operation ③ . For certain types of material， such as chalk ④ which may soften in wet weather， or when the excavated material has to be carried for more than two miles （3 km）， the excavation may be done using face shovel excavators loading into dump trucks. When rock is encountered， it is first shattered with explosives and then loaded by face shovel.
At the embankment， the earth is spread by the scrapers into a thin layer about 12 in.（305 mm） thick which is leveled by bulldozers and then compacted by caterpillar tractors towing rollers， or by self-propelled rollers which work more quickly. It is vital that the successive embankment layers are properly compacted so that the embankment is stable. The inevitable earth settlement will also be kept to a minimum to prevent damage or excessive maintenance to the finished road.
On completion of the earthworks， further shallow drain trenches， about 4 ft （1.2 m） deep， are constructed to keep the top layer of cutting or embankment free from water， which would weaken it.Pipes are laid in those trenches， which are then filled with gravel. In or adjacent to these trenches are laid further pipes to carry the water collected in road gullies from the finished road surface ⑤ .
survey v. 勘探，踏勘
terrain n. 地域，领地
aerial a. 空中的
stratum n. ［复］ strata 岩层，地层；薄片；阶层
geological stratum 地质层
gravel stratum 砂砾层
pit n. 坑，槽
trial pit 探井，试坑
bore v. 挖坑
gradient n. 坡度，倾斜度；梯度，陡度
purchase v. 购买
bills of quantity 费用
tender v. （常与for连用）投标（做某事），履行（某契约）
consulting engineer 顾问工程师
resident engineer 工地工程师，驻地工程师
stray v. 离群，走离；走失；迷失；闲逛
stump n. 树桩，残根
grub n. 挖，掘；（常与up，out连用）连根挖出
bulldoze v. （用推土机）清除，平整，挖出
bulldozer n. 推土机，（推土机前的）推土刀
blast v. 爆炸，炸开
explosive n. 炸药，爆炸物
ford n. 过水路面
cutting n. 挖方
collapse v. 坍塌
earthworks n. 土方（工程）
hydraulicity n. 水凝性（水泥）
hydraulic excavator 水力冲泥机
bucket n. 铲斗，勺斗
culvert n. 涵洞，管道，阴沟
strip v. 剥去，除掉，脱
stack v. 堆叠
caterpillar n. 履带，坦克车，战车
caterpillar tractor 履带式拖拉机
tow v. 拖，牵引
scraper n. 平土机，铲土机，电耙
box scraper 箱形电耙
blade n. 刀片，叶片
slice n. 薄片，一份，部分
shovel n. 铲，挖掘机
face shovel 正铲挖土机
excavator-type shovel 挖掘机
dump v. 倾倒（垃圾）
encounter v. 遇到，相遇
shatter v. 破碎
level v. 使……平坦，平等；夷平，摧毁
inevitable a. 不可避免的，必然的
settlement n. 沉降，陷落，下沉
trench n. 沟渠，管沟
gully n. 冲沟，集水沟
in accordance with 根据，按照
sight lines 视线，瞄准线
take… into account/ consideration 考虑
in competition with 与……竞争
decide upon 决定
single or twin-engined machines 单发动机或双发动机机器
speed up 加快，加速
earth settlement 土方沉降
①temporary haul roads指筑路时为运输材料而修的临时运输便道。
②up to sth.意为“多达”“直到”，例如：Research suggests that up to half of those who were prescribed the drug have suffered side effects.研究表明，在那些服用药物的人当中，有多达一半的人会受到副作用影响。
③while it is loading是时间状语从句。 to speed up…是目的状语；本句可译为：特别是在挖掘硬土时，铲土机在操作时还需用一辆后推式推土机将其顶住以加速操作。
④chalk意指白垩，是一种松软的方解石粉块，CaCO 3 ，含有不等量的硅石、石英、长石或其他矿物杂质，通常为灰白色或黄白色，从贝类化石中制得。
⑤这是一个倒装句，介词短语作状语置于句首引起倒装，主语是further pipes to carry the water collected in road gullies from the finished road surface。 in和adjacent to共用了宾语these trenches。本句可译为：在路边的沟里或附近铺设排水管，以排除从路面的水沟中汇集的水。