Figure 12.7
Set the Ditch Foreslope
subassembly to follow
the swale centerline
alignment and profile.
11. Click OK to dismiss the Target Mapping dialog. Click OK again to dismiss the Corridor
Properties dialog and rebuild the corridor. When viewed in 3D, the corridor should now
look like Figure 12.8.
Figure 12.8
The adjusted corridor
Note that the corridor has been adjusted to reflect the new target alignment and profile.
Also note that you may want to increase the sampling frequency. You can view the sections
using the View/Edit Corridor Section tools. You can also view the corridor in 3D by picking
it, right-clicking, and choosing Object Viewer. Use the 3D Orbit tools to change your view of the
Modeling a Peer-R oad Intersection
When you’re using the corridor model, an important distinction to make is that even though
you’re building a model, you aren’t designing it. Technically speaking, you could build the model
and design the intersection simultaneously; however, most users who attempt to ‘‘figure it out’’
as they’re constructing the model find the task tedious and frustrating.
The first step is to figure out how your intersection works. Give yourself some modeling guide-
lines, trends, and design constraints (but not actual hard elevations just yet), either onscreen or on
a small plotted schematic (see Figure 12.9).
Figure 12.9
Plan your intersection
model in sketch form.
Constant grade
around curbline
Grades adjust to match
road centerline profiles
cross section
cross section
cross section
High point
in middle
from CL out
Next, plan what alignments, profiles, and assemblies you’ll need to create the right combination
of baselines, regions, and targets to model an intersection that will interact the way you want.
Figure 12.10 shows a sketch of required baselines. Baselines are the horizontal and vertical
foundation of a corridor, as you saw in Chapter 11. Each baseline consists of an alignment and its
corresponding finished ground (FG) profile. You may never have thought of edge of pavement
(EOP) in terms of profiles, but after building a few intersections, thinking that way will become
second nature. The Intersection tool on the Create Design panel of the Home tab will create EOP
baselines as curb return alignments for you, but it will rely on your input for curb return radii.
Figure 12.10
Required baselines for
modeling a typical inter-
Baseline: Edge of Pavement Left
Baseline: Main Road
Baseline: Edge of Pavement Right
Baseline: Second Road
Figure 12.11 breaks each baseline into regions where a different assembly or different target
will be applied. The next exercise will give you hands-on experience in splitting regions along a
corridor baseline as a precursor to building an intersection automatically. Once the intersection
has been created, target mapping as well as other particulars can be modified as needed.
Figure 12.11
Required regions for
modeling an intersection
created by the Intersec-
tion tool
Region with intersection assembly
targeting Second Road Centerline
Region with typical assembly that
leaves off left lane and curb
Region with typical assembly
Region with typical assembly
Region with intersection
assembly targeting
Main Road Centerline
Using the Intersection Wizard
In Chapter 11, you learned briefly about regions. A baseline consists of a combination of an align-
ment and a profile, whereas assemblies are applied to specific regions. By default, every baseline
has one region, which you created in Chapter 11 whenever you made a new corridor. If certain
zones of a baseline require the application of a different assembly, you split a baseline into multiple
regions. The Intersection tool will do this for you automatically.
On the basis of the schematic you drew of your intersection, your main road will need two
assemblies to reflect two different road cross sections. The first assembly, as shown in Figure 12.12,
is the typical or ‘‘normal’’ case. The bulk of your neighborhood will use this typical assembly along
straight pieces that aren’t intersections, widening areas, or similar structures.
Figure 12.12
A typical assembly will
be applied to all ‘‘nor-
mal’’ regions.
The next assembly (see Figure 12.13) is a right laneonly assembly that you’ll apply through
the intersection. On the basis of your sketch, this particular main road won’t maintain a full crown
through the intersection; however, the right half of the road will be normal.
Figure 12.13
Right laneonly assem-

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