DETAIL SURVEY PRINCIPLE

v = Different of Height
HI = Height of Instrument
HT = Height of Target


I. Way to get the height of RL B if RL A is known ;
RL B = RL A + Hi instrument + v – Hi target


II. Way to get the height of RL A if RL B is known ;
RL A = RL B + Hi target – v – Hi instrument

DETAILS SURVEYING

DEFINITION OF DETAIL


Detail survey is actually to get the position and height of points on the earth surface. Besides, it can describe the actual features either natural or man-made available on a surveyed area onto a map or plan. Details surveying and tachometry are both shared the same principle. Data that is collected in details survey are produced in three dimensional (x, y, and z). This survey is doing to get the vertical and horizontal controls. x and y value are gathered from the controlled traverse which is established in the beginning of survey work. Before pick up any detail surveying field work, firstly is to prepare a set of specifications which set out the aims of the survey, the accuracy required, the amount and type of detail that is to be located and the intensity of any spot levels that are to be taken. Details surveying prepared involves considering the purpose of the survey, its accuracy requirements and its end product and choosing suitable equipment, techniques and drawing media that will ensure that the specifications are achieved.

Detail normally picked up from the control network (traverse) by total station with internal memory. Specific codes used to represent the details for ease. On maps and plans symbols can be used to represent detail. There is no universally agreed range of symbols for use in map and plan production. Booking for detail survey is still required though the readings have been recorded in the total station memory for checking purpose.

There are four categories of detail:

: Hard Details – the constructed features such as road, buildings and drainage
system.

: Soft Details – the natural features such as river banks, tree and
Vegetation.

: Overhead Details – the features that located on the ground such as electric
power lines and telephone lines.

: Underground Details – the features that located below of the ground such
as water pipes and sewer runs.



In this hydrographic surveying project, detail survey performed on the land where horizontal and vertical control points located. This uses to describe the location of those points from the natural or man-made features available there.Detail can be survey or pickup using total stations. There are information detail must be survey:

Ä Planimetric Information such as Permanent building / structure; Visible boundary feature like walls, fences or hedge; Road, track; Railways feature with arranged access; Water feature; Earth works or other relevant point. The accuracy of planimetric detail shall be such that the plan position of any well define point of detail shall be correct at the plan scale when checked from the nearest permanent control station.



: Height Information shall be provide a spot height throughout the survey area,
Contours and Obstructed ground.

: Detail Symbol are actually to guide drafting man to plot the drawing such as :

: BO : building,
: JO : road,
: OF : fence,
: P : spot level,
: MH : manhole etc.

CONTROL NETWORK

Horizontal Control

Traverse is a method in the field of surveying to establish horizontal control networks. Traverse networks involved placing the survey stations along a line or path of travel, and then using the previously surveyed points as a base for observing the next point. Types of traverse are:

: Link traverse
: Polygonal/Loop traverses
: Open/Free traverse
: Close traverse




Vertical Control

Leveling is one of the methods available in surveying for determining heights of points above (or below) an agreed datum, typically mean sea level. When leveling, it is possible to measure heights within a few millimeters and this order of precision is more than adequate for height measurement in the majority of surveying projects. As well as leveling it is worth noting that heights can also be measured by using total stations, handheld laser distance meters and GPS. The equipment required to carry out leveling is an optical, digital or laser level.To control heights at surveyed area, an established temporary bench mark (TBM) required inside or near the surveyed area. TBM needs to be established by fly level from any bench mark found nearby. In surveying a bench mark is specifically any permanent marker placed by a surveyor with a precisely known vertical elevation (but not necessarily a precisely known horizontal location). These reference points may be chiseled into a wall, or more typically, marked by small brass or aluminum disks, iron pins or bolts that are permanently attached to a stable foundation, such as concrete posts, bridge abutments, buildings, or a specifically constructed concrete block. These markers are then used as starting (control) points by subsequent surveyors and other users to establish the elevation of nearby points.

Land Survey Datum (LSD)

= It is used for engineering project.
= Usually used the vertical datum from established BM.
LSD is differing from MSL because reduced level from established BM is referring to MSL at Klang Port.
=Reduced sounding refer to LSD can merge with land details refer to vertical datum from established BM.