Highway Engineering: Building for Economic Structure
Highway Engineering is the branch of engineering that deals with the design, construction and maintenance of road surfaces, and the organization and supervision of the personnel required in highway construction and maintenance. Included are the required earthwork and the drainage system (except bridges and culverts which are classed as structural engineering guard fences and direction and warning signs.
Highway planning, location designing, construction and maintenance constitute highway or highway improvement. Several aspects including general planning and financing must be considered. Technical planning includes traffic needs of the area for a given period (generally 20 years) the type of construction to meet those needs such as the most suitable location, layout and capacity of the new route in relation to the traffic requirement, terrain to be tranversed, value of land needed for the right of way and estimated project costs.
Technological advancement has improved expertise in highway engineering and its related fields of soils, road building equipment and materials. Designs are now more economical, more reliable; and these developments have revolutionized construction methods. The highway engineer is aware that a highway can be attractive as well as useful.
This report recommends that the final plans for a proposed highway should be made public for comments so that, it necessary, the plans could be modified accordingly.
The advent of motorized land transportation in the twentieth century, the continuing increase in the number of vehicles and the attendant requirements for safer, smoother, and more durable thoroughfares have been a challenge to the highway engineer.
The data presented in this report is gathered from technical books, interviews, and expertise culled from work experiences.
Planning a proposed highway involves the gathering of statistical information from every available source. Surveys must be made to decide on the prospective location, the designed features and adjacent structures; date must be gathered to determine the volume of future traffic, and the speed and density throughout the day, the kinds and weights of the different road vehicles and the point most frequently traveled on existing roads, etc.
The first step toward highway location is intensive reconnaissance survey to start with deliberate study of all available general routes that may marked for careful inspection on the ground. Reconnaissance in the field is often accomplished by using a compass for measuring angles and pacing or stadia to determine distances. A unique bridge site or single mountain pass may become a primary control it no alternative exists. Likewise for scenic highways, the position of timbered areas, waterfalls and other attractions may become primary controls Cost factor such as favorable or unfavorable soil conditions, the number and sizes of structures and amount of excavation and grade, can similarly be classified as secondary controls.
7.1.2 Aerial Reconnaissance
Airplane flights are used in conducting highway reconnaissance. Aerial examination of possible routes gives comprehensive pictures that cannot be gained from the ground. Flights after ground reconnaissance is completed are of great advantage in clearly relating the proposed road to details of the surrounding country.
After the reconnaissance, it is usual to run a preliminary location survey first and to be followed by a final location survey. These are commonly made by transit and chaining methods.
The design of a highway must be correlated with features of location, the terrain, consideration of present and future use, the over-all plan for development of the transportation system and must be based upon both local and regional needs.
The detailed design of a highway project includes drawings on blue prints to be used for construction. These plans show, among other information, the exact location, the dimension of such elements as roadway width, the final profile for the road, the location and type of drainage facilities and the quantities of work involved, including earthwork and surfacing.
7.2.1 Soil Study
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 material removed can best be utilized for filling or for constructing embankments across low areas elsewhere on the project. For this, the engineer must analyze the gradation and physical properties of the soil, determine how the embankment can best be compacted and calculate the volume of earthwork to be done.
Adequate drainage is the most important element in road and highway construction. Much of highway engineering is devoted to carry streams across the highway’s right of way.
After designs are specified on the basis of plans, the work of building the road is begun The preparation for the roadbed’s foundation called grading is done first. It includes round excavation, the formation of embankments and the smoothing of slopes. The first step is to remove all vegetation from the roadway section, an operation in which the bulldozer plays a large part. Then, a heavy earth-moving machinery moves materials from cut section into fill sections, where the materials is placed in layers, brought to the proper moisture content, and compacted to the required density.
7.3.1 Highway Pavement
Highway paving is the smooth waterproof having the material composition, strength and durability needed to withstand the estimated traffic and weather conditions. The types of pavement may be classified as low cost, intermediate and heavy duty.