Iowa DOT's policy
is to be
sensitive to the environment
and foster and enhance
environmental stewardship.
IOWA DEPARTMENT OF TRANSPORTATION
Presents
ROCKS AND ROADS
Unit 4: How are highways designed?
B. Drawing Viewpoints
Have you ever tried to draw a three-dimensional (3D) object? It is very difficult to draw a 3D object on a flat sheet of paper. In order to get around this difficulty, engineers show different two-dimensional (2D) viewpoints that together show the total object. To show most 3D objects it is necessary to draw three different viewpoints.
Imagine an object, such as a cardboard box, is sitting on the floor. You would need to draw three pictures based on what you see from three different locations relative to the cardboard box. These views might be above the cardboard box looking down, and views from the left and right looking back at the cardboard box. When you look at all three drawings, you can then picture what the object should look like.
The top, left and right sides of the cardboard box would all look the same in a one-dimensional drawing.
If an object is symmetrical, two or even three of these viewpoints might show the same thing. There is also a type of drawing called an isometric view that shows a 3D object on a 2D drawing.
Engineers have special names for these different viewpoints on the construction plans. The first of these, the plan view, shows the project from above, as if you were looking down on it from an airplane.
The second of these, the profile view or elevation view, shows the project from way off to the side looking back at the project.
The third view, called a cross section view, shows what you would see if you were to make a slice through the project and look down the roadway.
