Chapter 11
Easy Does It: Basic Corridors
The corridor object is a three-dimensional road model that combines the horizontal geometry of
an alignment, the vertical geometry of a profile, and the cross-sectional geometry of an a ssembly.
Corridors range from extremely simple roads to complicated highways and interchanges. This
chapter focuses on building several simple corridors that can be used to model and design roads,
channels, and trenches.
By the end of this chapter, you’ll learn to:
Build a single baseline corridor from an alignment, profile, and assembly
Create a corridor surface
Add an automatic boundary to a corridor surface
Understanding Corridors
It its simplest form, a corridor is a three-dimensional combination of an alignment, a profile, and
an assembly (see Figure 11.1).
You can also build corridors with additional combinations of alignments, profiles, and assem-
blies to make complicated intersections, interchanges, and branching streams (see Figure 11.2).
The horizontal properties of the alignment, the vertical properties of the profile, and the
cross-sectional properties of the assembly are merged toget her to form a dynamic model that
can be used to build surfaces, sample cross sections, and much more.
Most commonly, corridors are thought of as being used to model roads, but they can also be
adapted to model berms, streams, lagoons, trails, and even parking lots (see Figure 11.3).
Creating a Simple Road Corridor
The first ingredient in any corridor is an alignment. This alignment is referred to as a baseline.A
baseline requires a corresponding profile and an assembly. A corridor can have multiple base-
lines, and a baseline can be divided into regions. You’ll see how regions are used a little later in
this chapter. (Corridors with multiple baselines are discussed in Chapter 12, ‘‘The Road Ahead:
Advanced Corridors.’’)
When you create and iterate a design, you may be tempted to use its default name, such as
Alignment-64 or Basic Lane-(3)(3), instead of a much more meaningful name. Before building a
corridor, even a simple corridor, it is important to make sure your alignments, profiles, assemblies,
and subassemblies have good names. If you get into the habit of giving your objects significant
and meaningful names e ven for the simplest corridor you w ill be rewarded when you build
larger corridors (see Figure 11.4).
Figure 11.1
A simple corridor
Figure 11.2
An intersection modeled
with a corridor
Figure 11.3
modeled with a corridor
Figure 11.4
Check the names
of your alignments,
profiles, assemblies, and
This exercise gives you hands-on experience in building a corridor model from an alignment, a
profile, and an assembly:
1. Open the Simple Corridor.dwg file, which you can download from
masteringcivil3d2010. Note that t he drawing has an alignment, a profile view with two
profiles, and an assembly, as well as an existing ground surface.
2. Change to the Home tab and select Corridor Create Simple Corridor from the Create
Design panel. The Create Simple Corridor dialog opens.
3. In the Name text box, give your corridor a meaningful name, such as Project Road. Keep
the default values for Corridor Style and Corridor Layer (see Figure 11.5).
Figure 11.5
Change the corridor
name to something
meaningful for easy
4. Click OK to dismiss the dialog.
5. At the Select baseline alignment <or press enter key to select from list>: prompt,
pick the alignment in the drawing. Alternatively, you could press
and select your align-
ment from a list.
6. At the Select a profile <or press enter key to select from list>: prompt, pick the
Finished Ground profile (the profile with labels) in the drawing. Alternatively, you could
and select your profile from a list.
7. At the Select an assembly <or press enter key to select from list>: prompt, pick the
vertical line of the assembly in the drawing. Alternatively, you could press
and select
your assembly from a list.
8. The program will process and build the corridor. Dismiss the Panorama if it appears over
the road centerline alignment as shown in Figure 11.6.
Figure 11.6
The completed simple
Utilities for Viewing Your Corridor
Once your corridor is built, chances are you will want to examine the corridor in section view
and use 3D to view the model and check for problems. For a station-by-station look at a corridor,
pick the corridor and choose Corridor Section Editor from the Modify panel. The Section Editor
contextual tab opens (see Figure 11.7).
Figure 11.7
The Section Editor
contextual tab with
the Corridor Edit Tools
panel pinned open
The Station Selection panel on the Section Editor contextual tab allows you to move forward
and backward through your corridor to see what each section looks like. There are also options

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