【正文】 of roads can adapt below each day and night mediumduty truck volume of traffic 200. The county route is refers to has countywide (countylevel city) politics,the economicsignificance, connects in the county and the county the main township (town), the principal modities production and the collection and distribution center road, as well as does not belong to the federal highway, provincial road39。s township and the township and the township and the exterior contact road. Township is responsible by the people39。s year mean diurnal volume of traffic 25000~55000. The six traffic lane highways ought to be able to adapt each kind of automobile reduce passenger vehicle39。s year mean diurnal volume of traffic 60000~100000. 2nd, the arterial road to supply the automobile and may according 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 vehicle39。s year mean diurnal volume of traffic 25000~55000. 3rd, the secondclass road to supply the automobile travel the twolane highway. Can adapt each day and nights 3000~7500 mediumduty truck volume of traffic generally. 4rd, tertiary highways to mainly supply the automobile travel the twolane highway. Can adapt each day and nights 1000~4000 mediumduty truck volume of traffic generally. The 5, four levels of roads to mainly supply the automobile travel the twolane or the singlelane highway. The twolane four levels of roads can adapt below each day and night mediumduty 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 consideration 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 features 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 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 rightofway. and estimated cost 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 out t\t one time or whether construction must be in stages with each stage initiated as funds bee 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 owners of adjacent property and the general public. Users of improved highways benefit from decreased cost of transportation, greater travel fort, increased safety and saving of time. They also obtain recreational and educational benefits. Owners of abutting or adjacent property may benefit from better access, increased property value, more effective police and fire protection, improved street parking greater pedestrian traffic safety, and the use of the street rightofway for the location of public utilities such as water lines and sewers. Evaluation of various benefits from highway construction 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 procedure. 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 generation, air pollution disturbance of areas traversed destruction of existing housing and possible alternate routes. Highway engineers must also assist in the acquisition of rightofway needed for new highway facilities Acquisition of the land required for construction of expressway lending into 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 ext