Levels
 Details of Construction
 Tilting Level
 Dumpy Level
 Automatic Level
 Levelling Staff
 Setting Up An Instrument
 Errors/Calibration

Levels

Examples Of Usage

Levels can be used for:

• Determining the height of a particular point
• Determining differences in height between points
• Determining the contours of a land profile
• Providing data for road cross-sections
• Providing data to calculate volumes for earthworks
• Setting out level surfaces for construction 
• Setting out inclined surfaces for construction

Factors Which Influence The Use Of Levels

• Clear lines of sight needed between known and unknown points. There is no need to physically travel between the target and reference points.
• Height precision is dependant upon the precision of instrument used and the length of the line of sight.
• Height accuracy is maintained through proper adjustment of the level and correct field procedures.

Survey Methods Used For

Levels determine differences in height between two or more points.

    Levelling

Models

To determine the difference in height between different points it is necessary to produce a line of sight. This requires the use of an instrument. In surveying, this instrument is known as a surveyor's level, often generically known as a dumpy level although, as we will see, this is not strictly correct. All of levels consist of a telescope with a cross hair or gun sight, mounted on a device that enables us to orient the device in a horizontal plane.

There are three types of levels:

• dumpy levels
• tilting levels
• automatic levels

The differences between the three types being in the way in which the instruments are designed to be adjusted to give a horizontal line.

Precision

The three types of levels can be further divided into different classes defined by their precision.

Precise

Very accurate instruments for geodetic or any other very precise levelling. It should be possible to level such an instrument to within +0.2".

Medium Accuracy

These are used for engineering surveys. They may be tilting or automatic instruments capable of being levelled within the range of 1/2 - 1".

Builders

Low accuracy, short range levelling such as setting out on building sites. Although described as being low accuracy instruments, this is relative to the other classes of levels and the results obtained with this class of instruments will be well within the tolerances required on the majority of construction sites.