Technical data

Chapter 5 Working with Surfaces
202
Key Concepts
■
The volume results are only as good as the surface definitions. The
more complete the surface data, the better the volume calculations.
■
The grid method offers a quick volume result. Because it is a grid,
however, you can potentially miss surface irregularities, such as a
curb or depressions, which would affect your volume results. This
method creates a volume surface that you can view and manage
from the Terrain Model Explorer.
■
The composite method uses all the data from the first and second
surfaces. This method creates a volume surface, and the results are
the exact surface difference total. This method creates a volume
surface that you can view and manage from the Terrain Model
Explorer.
■
The section method interpolates cross sections from the two
surfaces of the current stratum, and generates volumes using one of
two methods: Prismoidal or Average End Area. This gives you
sections that you can plot in order to verify areas and submittals.
This method does not create a volume surface.
To calculate volumes
Steps
Use
to look up
1
Define at least two surfaces, such as existing
ground and proposed ground.
Build a Surface
2
From the Terrain menu, choose Select Current
Stratum to create a stratum that defines the two
surfaces that you compare.
Define a Stratum
3
From the Terrain menu choose Site
Definition
➤
Define Site to define the site area.
A site is essentially a rectangular area in which all
volume calculations are performed. It also defines
the grid size that is used when creating a grid
surface.
Define a Site for Volume
Calculations
4
To calculate volumes using the section method,
select Terrain
➤
Section Volumes
➤
Sample
Sections to generate the cross section data.
Sample Section Data for
Volume Calculations