SURVEY ENGINEERING 1

Introduction

• Levelling is the operation required in the determination or, the comparison of

heights of points on the surface of the earth.

• Levelling also is the procedure used when one is determining differences in

elevation between points that are remote from each other.

• An elevation is a vertical distance above or below a reference datum. 
• In land Surveying, the reference datum is mean sea level.

Uses of levelling

1. To get a different level of 2 points.

2. To build up Bench Mark and Temporary Bench Mark for the construction site.

3. To produce cross section or long section and producing land profile.

4. To produce contour map for each construction site.

5. To control the vertical level in setting out work.

6. To know the elevation of the construction site or any new development

Important word or terminology in Levelling

1. Reduced Level - reduced/original level for each points

2. Bench Mark (BM ) - is a permanent point of known elevation.

• Bench mark are established by using precise levelling technique and

instrumentation.

• Bench mark elevations and locations are published by the federal

department called Jabatan Ukur dan Pemetaan Malaysia (JUPEM).

3. Temporary Bench Mark (TBM)

• Is a semi permanent point of known elevation.

• TBMs can be flange bolt on fire hydrants, nails in the roots, top corners

of concrete culvert etc.

• The elevations of TBMs are not normally published but are available in

the field notes of various license surveyors.

Important word or terminology in Levelling

4. Turning point (TP)

• Is a point temporarily used to transfer an elevation.

5. Backsight (BS)

• Is a rod reading taken on appoint of known elevation in order to establish

the elevation of the instrument line of sight.

6. Height of instrument (HI)

• Is a elevation of the line of sight through the level (i.e. – elevation of BM +BS = HI).

7. Foresight (FS)

• Is a rod reading taken on a turning point, BM or TBM in order to

determine its elevation.

Pond Bubble

When pond bubble is centred the instrument’s standing axis.

is approximately vertical.

The compensator in the instrument take over and adjust

the optical Line of Collimation so that it is horizontal (hopefully)

When the instrument is rotated the compensator ensure that

a horizontal plane of collimation is swept out (hopefully).

Levelling Equipment

 1) Engineering level/dumpy level

• Useful for engineering work either in the building or construction sites.

• The accuracy is enough for the civil engineering work.

• The main body of this equipment is adjustable telescope.

2) Surveying staffs/rods

• Staffs used for ordinary levelling work are sectional and are assembled either

telescopically or by slotting onto one another vertically.

• Generally, the body or the rod is either fiberglass or wood.

• Normally lengths of staff is 5 meter and the reading value is in metric.

3) Tripods

• To support the dumpy level or engineering level equipment.

4) Measurement tape

• Use for measure the distance of two staff.

• The ideal distance between staff A and B is around 30 – 50 meter.

5) Log Book

                                                Basic concept of closing levelling