Culvert construction: the plan location and invert grade of culverts are shown on the construction plan and profile. The intersection of the culvert and the highway is shown on plan and is identified by its highway stationing (chainage) number, and length of culvert of the construction profile shows the inverts for each end of the culvert. The grade stakes references the culvert and gives the cut or fill to the top of the footing for the open footings culverts, to the top of the slab for concrete box culverts, or to invert of the pipe for pipe culverts. If the culverts is long intermediate grade may be required. There are 3 types of culver 1, open footing 2. concrete box 3. Circular, are etc in our case the culvert will construct according to the plan or design shown us at specified interval of change.
Accuracy requirements for structure construction are generally of the highest order for survey layouts. Accuracy requirements for long-span bridge is 1/10,000. It is depend upon complexity of structure, type of construction made real specified ultimate design use of the facility. The accuracy required for any specific project can be specified in contract documents or it can be left to the common sense and experience of the surveyor.
Preliminary surveys for bridge includes base holes drilled for foundation Investigation bridge designers indicate the location of a series of bore holes on highway design plan. The surveyor locates the bore holes in field by measuring centerline changes, offsets and ground elevators. As the bridge design progresses, the surveyor may have to go back to the site several times to establish horizontal and vertical control for additional bore holes, which may be required for final footing design and also he establish the field points by polarities from coordinator movements.
The surveyor may also establish the points by the more traditional and change and offset measurements.
Field project report reporting the bridge construction since we are surveyor we have to go several times to the field to locate the bore holes, horizontal and vertical control station for additional bore holes and finally we ready it for construction.
Highway Drainage and Design
Highway drainage is the process of removing and controlling excess surface and subsoil water within the right of way. This includes interception and diversion of water from the read surface and sub grade. The installation of suitable surface and sub-surface drainage system is an essential part of highway design consideration.
During rains, part of the rain water flows on surface and part of it percolates through the sol mass as gravitational water until it reaches the ground water below the water table. Removal and diversion of surface water from the roadway and adjoining land is termed as surface drainage. Diversion or removal of excess soil water from the grade is termed as sub-surface drainage some alter is retained in the pores of the soil mass and on the surface of soil particles by surface tension and absorptive forces, which cannot be drained off by normal gravitational method and this water is termed as held water. Importance of highway drainage
Significance of Drainage: – an increase in moisture content causes decreases in strength or stability of a soil mass. The variation in soil strength with moisture content also depends on the soil type and the made of stress application.
Drainage is important because of the following reasons:
Excess moisture in soil sub-grade causes considerable lowering of its stability.
Increase in moisture causes reduction in strength of many pavement material
Excess water on shoulder and pavement edge causes considerable damage.
Erosion of soil form top of un surfaced roads and slopes of embankment, cut and bill side also due to surface water.
The surface water is to be collected and then disposed off. The water is first collected in longitudinal drains, generals in side drains and then the water is disposed off at the nearest stream, valley or water causes.
Cross drainage structures like culverts and small bridges may be necessary for the disposal of surface water from road side drains.
Collection of Surface Water: – the water from the pavement surface is removed by providing the comber or cross slope to the pavement. The rate of this cross slope is decided based on type of pavement surface and amount of rainfall.
In rural highways, he water which is drained from the pavement surface has also to drain across the shoulders before it lead to the side drops. Hence the shoulders of these roads are constructed with suitable cross slope so that the water is drained across the shoulders to the side drains. These side drains of rural roads are generally open ditch (unlined drains of trapezoidal shape. These side drains are provided parallel to the road alignment and hence these are called longitudinal drains. In embracement the longitudinal drains are provided on one or both sides of formations. Covered drains or drainage trenches properly filled with layer of course and gravel may be used.
In urban roads because of the limitations of the land width and also due to the presence of foot path, dividing island, and other roads facilities, it is necessary to provide underground longitudinal direction between the cerb and the pavement for short distances. Section of a typical catch pit with grating to prevent the centers of rubbish into the drainage system