2.0

Defining the Transition Regions on a Template
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Defining the Transition Regions on a Template
Transition regions are used to stretch templates horizontally and/or vertically in
order to accommodate areas where the roadway offsets or elevations are
irregular, such as when a road widens for a passing lane. By using transition
regions on a template, you do not need to have multiple templates to
accommodate these varying conditions. You can define up to sixteen transition
regions on a template, eight left and eight right.
The basic rules of defining a transition region are as follows:
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The control point is moved to the required offset and/or elevation when
transitioning is applied to the template.
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The region point is the outer edge of the template segment that will stretch
when the control point moves.
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To achieve the surface modification when a transition is applied to a
template, any surface line that is intersected by the vertical plane of the
region point will be modified between that point and the next point on the
surface toward the centerline.
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The control and region points can be at the same or at different locations.
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The control point can never be closer to the centerline than the region point.
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Only the top of the subgrade surface definition is modified by the transition
(the portion that is drawn before the template is defined). The bottom of the
subgrade is still calculated based on its depth and grade criteria.
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The Pinned or Dynamic option only applies to the central region between
the innermost left and right transitions.
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The template surfaces can cross the centerline only if the innermost left and
right transition regions are Dynamic.
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The transition region cannot stretch toward the centerline if the Constrained
option is used.
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The Hold Grade or Hold Elevation option is used when the template is
modified by a horizontal transition (offset) only. It is disregarded if a vertical
transition is applied.
NOTE
If you have already defined transition regions for a template, then you can
view this information by using the Display option of the Edit Template
command. Under the Display options, select the TType option. For more
information, see Redrawing the Template Display in this chapter.