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43.6.4
Description
Roads - General
A DTM consists of several 3D triangles. DTMs do not include information relat-
ing the DTM to a centreline. Positions are defined by easting, nothing and
height values.
c
a
Road_006
a
Height difference from the triangle of the DTM found in the same ver-
tical line as the measured point
b
Easting of coordinate system
c
Northing of the coordinate system
A layer is a combination of lines that form a 3D surface relative to a centreline.
Thus it is possible to define points by chainage or station, offset and height.
Refer to "43.2.3 Design Data" for more information.
b
c
Road_007
a
Chainage or station
b
Layer Offset
c
Layer height difference
Road - Stake Offset and Stake Height Difference
When conducting a stake out, the aim is usually to mark the position of geo-
metric elements defined by the design. For example, in the graphic below, the
catch point of a slope. A point can be staked either directly or indirectly. For a
directly staked point, the peg ends up at exactly the position of the point to be
staked. Staking the same point indirectly, the peg will be placed with a certain
offset to the point.
b
a
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