1、The road (highway)The road is one kind of linear construction used for travel. It is made of the roadbed, the road surface, the bridge, the culvert and the tunnel. In addition, it also has the crossing of lines, the protective project and the traffic engineering and the route facility.The roadbed is
2、 the base of road surface, road shoulder, side slope, side ditch foundations. It is stone material structure, which is designed according to routes plane position .The roadbed, as the base of travel, must guarantee that it has the enough intensity and the stability that can prevent the water and oth
3、er natural disaster from corroding.The road surface is the surface of road. It is single or complex structure built with mixture. The road surface require being smooth, having enough intensity, good stability and anti-slippery function. The quality of road surface directly affects the safe, comfort
4、and the traffic.The route marking is one kind of traffic safety facility painted by oil paint or made by the concrete and tiles on high-level, less high-type surface. Its function is coordinating the sign to make the effective control to the transportation, directing the vehicles skip road travel, s
5、erving unimpeded and the safe purpose. Our countrys road route marking has the lane median line, the traffic lane boundary, the curb line, the parking line, the conduction current belt, the pedestrian crossing line, the four corners center circle, the parking azimuth line. The route marking has the
6、continual solid line, the broken line and the arrow indicator and its color uses the white or the yellow.The arch of bridge is the structure which strides over rivers, mountain valley and channel. It is made generally by steel rod, concrete and stone. The tunnel is the cave which connects both sides
7、 of the road. The technique of this construction is very complex, the cost of the projects is higher than common road .However, it reduces the driving distance between two places, enhances the grade of the technical in building the road and guarantees the cars can drive fast and safely, thus reduces
8、 the cost of transportation.The protective project is to protect and consolidate the roadbed in order that it can guarantee the intensity and the stability of the road, thus maintains the automobile to pass through safely.In order to guarantee that safe operation of the highway transportation, besid
9、es the highway engineering and the vehicles performance, it must have some traffic signal, route marking, each kind of director and demonstrate facility. The highway marking uses certain mark and draw symbol, simple words and number, then installs in the suitable place to indicate the front roads co
10、ndition or the accident condition including the informational sign, the warning signal, the prohibitory sign, the road sign and so on.The road which Join city, village and industry, mainly are used for the automobile and has certain technical standard and the facility path can be called the highway.
11、 “The highway” in Chinese is the modern view, but it was not existed in old day. It gets the name from the meaning of being used for the public traffic. Where are the human, there are the road. It is a truth. However, the road is not the highway. If we talk the history about the road, the earliest h
12、ighway is that built by the old Egyptians for making the pyramid. Next is the street which built by the Babylon people about 4000 years ago. All these are much earlier than our country.About 500 B.C., the Persian Empire road has linked up East and West, and connected the road to China. It is the ear
13、liest and longest Silk Road. 2500 years ago, it might be the greatest road .The ancient Rome Empires road was once celebrated; it took Rome as the center, all around built 29 roads. Therefore it came out one common saying: every road leads to Rome.The roads construction is the process to enhance tec
14、hnique and renew the building materials. The earliest is the old road, it is easy to build but it is also to destroy. If there is too much water or cars, it will be uneven and even be destroyed. The macadam road appeared in the Europe which outbalanced the earliest mud road. Then the brick road appe
15、ared which was earlier than China. It was one great breach that we molded bitumen on the macadam road. From ancient times to the present, China has courier station and courier road, while the first more advance road was the one that from Long Zhou in Gang Xi to Zhen Nan Guan in 1906. The difference
16、between Road and pathThe path is the project for each kind of vehicles and people to pass through. According to its function, we can divide it into the urban road, the road, the factories and mines path, the forest road and county road.The classification of roadFirst, according to administrative ran
17、k, it includes national highway, province road, county road and the special road. Generally the national highway and province road are named main line; the county road is named branch line. The national road is the main line and has political and economy significance, including the important nationa
18、l defense road and the road collecting our capital with other provinces, autonomous regions and municipalities. It is also the road links the economy center, seaport hinge, factory and important strategic place. The highway striding over different provinces are built, protected and managed by the sp
19、ecial organizations which are approved by the ministry of communications. The provincial road is the main line built, protected, managed by the road manage department .It is full of political and economic sense to the whole province. The single way four levels of roads can adapt below each day and n
20、ight medium-duty truck volume of traffic 200.The county route is refers to has county-wide (county-level city) politics,the econom-icsignificance, connects in the county and the county the main township (town), the prin-cipal commodities production and the collection and distribution center road, as
21、 well as does not belong to the federal highway, provincial roads county border the road. The coun-ty route by the county, the city road Department responsible for the work is responsibleto construct, the maintenance and the management. The township road refers to mainly the road which for the towns
22、hip (town) the villa-geeconomy,the culture, the administration serves, as well as does not belong to above t-hecounty route between roads township and the township and the township and the exte-rior contact road. Township is responsible by the peoples government to construct, the m-aintenance and th
23、e management. The special-purpose road is refers to feeds specially or mainly supplies the factories andmines,the forest region, the farm, the oil field, the tourist area, the military importantplace and so on and the external relations road. The special-purpose road is responsibleby the special-pur
24、pose unit to construct, the maintenance and the management. May also entrust the local road department to construct, the maintenance and the management.Second, according to the use duty, the function and adapts the volume of traffic division.According to our country present Highway engineering Techn
25、ical standard the roadaccording to the use duty, the function and the adaptation volume of tra-fficdivides into highway,arterial road, second-class road, tertiary highway, four level of road five ranks:1st, the highway to feed specially the automobile and should control the difference c-ompletely re
26、spectively toward the dividing strip on roads travel the multiple highway. The four traffic lane highways ought to be able to adapt each kind of automobile reduce passenger vehicles year mean diurnal volume of traffic 2500055000. The six traffic lane highways ought to be able to adapt each kind of a
27、utomobile reduce passenger vehicles year mean diurnal volume of traffic 4500080000.The eight traffic lane highways ought to be able to adapt each kind of automobile r-educe passenger vehicles year mean diurnal volume of traffic 60000100000.2nd, the arterial road to supply the automobile and may acco
28、rding to need to control the difference respectively toward the dividing strip on roads travel the multiple highway. The four traffic lane arterial roads ought to be able to adapt each kind of automobil reduce passenger vehicles year mean diurnal volume of traffic 1500030000. The six traffic lane ar
29、terial roads ought to be able to adapt each kind of automobile reduce passenger vehicles year mean diurnal volume of traffic 2500055000.3rd, the second-class road to supply the automobile travel the two-lane highway.Can adapt each day and nights 30007500 medium-duty truck volume of traffic generally
30、. 4rd, tertiary highways to mainly supply the automobile travel the two-lane highway. Can adapt each day and nights 10004000 medium-duty truck volume of traffic generally.The 5, four levels of roads to mainly supply the automobile travel the two-lane or the single-lane highway. The two-lane four lev
31、els of roads can adapt below each day and night medium-duty truck volume of traffic 1500. Highway engineering includes Highway planning location design and maintenance. Before the design and construction of a new highway or highway improvement can be undertaken there mint be general planing and cons
32、ideration of financing As part of general planning it is decided what the traffic need of the rea will be for a considerable period, generally 20 years, and what construction will meet those needs. To assess traffic needs the highway engineer collects and analyzes information about the physical feat
33、ures of existing facilities, the volume, distribution, and character of present traffic, and the changes to be expected in these factor. The highway engineer must determine the most suitable location layout, and capacity of the new route and structures. Frequently, a preliminary line or location and
34、 several alternate routes are studied. The detailed design is normally begun only when the preferred location has been chosen.In selecting the best route, careful consideration is given to the traffic requirements terrain to be traversed value of land needed for the right-of-way. and estimated cost
35、of construction for the various plans. The photogrammetric method, which makes use of aerial photographs is used extensively to indicate the character of the terrain on large projects where it is most economical. On small project,Financing considerations determine whether the project can be carried
36、out tt one time or whether construction must be in stages with each stage initiated as funds become available. In deciding the best method of financing the work, the engineer makes an analysis of whom it will benefit. Important highways and streets benefit* in varying degrees, three groups* users ow
37、ners of adjacent property and the general public.Users of improved highways benefit from decreased cost of transportation, greater travel comfort, increased safety and saving of time. They also obtain recreational and educational benefits. Owners of abutting or adjacent property may benefit from bet
38、ter access, increased property value, more effective police and fire protection, improved street parking greater pedestrian traffic safety, and the use of the street right-of-way for the location of public utilities such as water lines and sewers.Evaluation of various benefits from highway construct
39、ion is often difficult but is a most important phase of highway engineering. Some benefits can be measured with accuracy, but the evaluation of others is more speculative. As a result numerous methods arc used to finance construction, and much engineering work may he involved in selecting the best p
40、rocedure.Environmental evaluation. The environmental impact of constructing highways has received increased attention and importance. Many projects have been delayed and numerous others canceled because ot environmental problems. The environmental study or report covers many factors, including noise
41、 generation, air pollution disturbance of areas traversed destruction of existing housing and possible alternate routes. Highway engineers must also assist in the acquisition of right-of-way needed for new highway facilities Acquisition of the land required for construction of expressway lending int
42、o the central business areas of cities has proved extremely difficult i the public is demanding that traffic engineers work closely with city planners, architects, sociologists and all groups interested in beautification and improvement of cities to assure that expressways extendinx through metropol
43、itan areas be built only after coordinated evaluation of all major questions, including the following;(1) Is sufficient attention being paid -to beautification of the expressway itself? (2) Would a change in location preserve major natural beauties of the city? (3) Could a depressed design he logica
44、lly substituted for those sections where an elevated expressway is proposed? (4) Can the general design he improved to reduce the noise created by large volumes of traffic? (5) Are some sections of the city being isolated by the proposed location?Detailed design. Detailed design of a highway project
45、 includes preparation of drawings or blueprints to be used for construction. These plans show, for example, the location, the dimensions of such elements as roudway width* the finaj profile for (he road, the location and type of drainage facilities, and the quantities of work involved, including ear
46、thwork and surfacing.In planning the grading operations the design engineer considers the type of material to be encountered in excavating or in cutting away the high points along the project and how the rnaterial removed can best be utilised for fill or for constructing embankments across low areas
47、 elsewhere on the project. For this the engineer must analyze the gradation and physical properties of the soil, determine how the embankments can best be compacted, and calculate the volume of earthwork to be done. Electronic calculating procedures are now sometimes used for the last step. Electron
48、ic equipment has also speeded up many other highway engineering calculations. Powerful and highly mobile earth moving machines have been developed to permit rapid and economical operations., Selection of the type and thickness of roudway surfacing to be constructed is an important part of design. Th
49、e type chosen depends upon the maximum loads to be accommodated, the frequency of these loads and other factors. For some mures, traffic volume may be so low that no surfacing is economically justified and natural soil serves as the roadway. As traffic increases, a surfacing of sandy cluy, crushed slag, crushed stone caliche crushed oyster shells, or a combination of these may be applied. If gravel is used, it usually contains sufficient clay and fine materi
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