NCDOT Roadway Basic Template Fundamentals

The Power and Flexibility of Parametric Constraints
      In most cases, users should not have to modify components at the template level. Parametric constraints can be applied after the template has been dropped in Roadway Designer to change default constraints values as drawn. Parametric constraints can only be override by target styles and point controls.

Symmetrical vs. Asymmetrical Controls
      When mirroring a component, any constraints with a horizontal value will have a negative sign automatically added as a prefix to the label. Only horizontal associated constraints such as horizontal, slope, and vector-offset labels are affected. Vertical constraint labels such as pavement depths are not affected. As a result, the negative label will not display under the Parametric Constraints dialog box. This works well with symmetrical controls such as pavement widths and side slopes where both sides of the road can be set to one (same) value.

     If asymmetrical controls are desired, then the parametric constraint labels will have to be modified to be distinguishable and displayed in the Parametric Constraints dialog box. Users will have to do this at template level. For instance, if the right side of the side slope is fixed at 3:1 and left side of the road is fixed at 2:1, then change the label "SS_Fill Slope" and "-SS_Fill Slope" to "SS_Fill Slope RT" and "SS_Fill Slope LT", respectively. The same method can be used with asymmetrical pavement widths and bridge rail offsets designs.

For a complete list of available parametric constraints, see the Parametric Constraints Appendix.

Mirroring and Applying Affixes
      All components in the template library are built as the right side of the road only. When assembling the components together to create a complete template for both sides of the roadway, use "mirror" with Apply Affixes checked ON. This will separate the right side components from their left side counterparts. Use exclusively prefixes "LT_" for the left side and "RT_" for the right side. This preference can be saved in the project XIN.

Do this only when creating a complete template (both sides of the road), NOT when creating individual components (right side of the road only).

Core vs. Compound
      Core components and core end conditions are the primary fundamental building blocks for a complete set of templates. When two or more core components or end conditions are assembled together, they are then considered to be compound components or compound end conditions. In most cases, compound components and compound end conditions are the fastest, most efficient way to assemble a template because they are fully constrained. In rare cases, a template must start from each basic core component or core end conditions. Remember that some of the points inside core component and end condition containers are not fully constrained.

Backbone Only Templates (BBO)
      A template "backbone" is all of the components of a template excluding the side slope end conditions. A bridge template is by default a backbone only template. Road template backbone is defined from outside shoulder point to outside shoulder point (or berm to berm for C&G sections). The purpose of backbone only templates (BBO) is to allow users to choose various standard side slope end conditions to their project specific needs. Instead of building a complete template for every possible side slope end condition combinations, a single backbone only template can be used.

     For example, for a undivided facility shoulder section backbone only template, users can choose the standard local, arterial, or freeway side slope as an end condition. In addition, a fixed 2:1 or 3:1 side slope end condition can also be selected.

Two-Type Pavement and Shoulder Standards

Note that parametric constraints can be used to vary the pavement width as well as the paved shoulder widths.

Sequence/Order - "PIO"
      When assembling templates, components must be placed in certain sequence to ensure proper working order. Employ the "PIO" method (Pavement, Inside, then Outside). Whether the template is a divided facility or an undivided facility, always start with the pavement component first. Then work toward the inside of template. This may include inside shoulder, then median work. Inside components are not required for undivided facilities. Lastly, work toward the outside of the template. Start with the shoulders and end with the various end conditions.

Reference Points
      Reference points are used extensively throughout the template library. Reference points are a little bit different from null points. Because each core component only "see" the points that are placed within the component container, core components can exist by themselves. When assembling two or more core components together (compound components), it is necessary to establish "reference points" in order to constrain two points from two different core components.

     For example, to lock the rollover rate on the shoulder (OEOP point), the centerline PGL point must be "seen" by the shoulder component. Since the centerline PGL point is on the core pavement component, and not shoulder component initially, a "referenced" centerline PGL point is required to be established inside the shoulder component container. This way, the rollover lock can be set on the shoulder component without having all of the pavement component points attached.

     Reference points should have the same name to avoid confusion and they reside in the same location as their primary counterparts. However, they do not have to be fully constrained like their primary counterparts since component points have a system of overwrite priorities.

Point Overwrite Priority
     When two points are meshed together, the new point is overwritten by the original point (what's already there). The name and any constraints of the original point property are kept and the new point properties are discarded.

Insertion Point Handle
     It is important to note the location of the key insertion point handle in the lower left corner preview screen with the matching point on the active template container that it is designed to mesh up with. In most cases, it is at the component container origin ((0,0) but not always in case with median components) highlighted by a light blue square under the component preview screen.

     Since the point on the active template container that the key insertion point handle is designed to mesh up with is sometime not as apparent, it is critical that all documentations identify these two points. Note that along with the insertion point, other points in the active template container can also be designed to be overwritten when they are put together at the same location.

Display Rules vs. End Condition Priorities
     Display rules are written to display or undisplay certain components in certain condition. For example, when the seek EEOP point moves (EEOP line found), display a widening pavement component. If the seek EEOP point does not move, then by default undisplay the widening pavement component ( all new pavement section).

     End condition priorities are design to resolve conflicts with the various end condition "branches". In our standard side slope components, there are several branches that can tie to natural ground. EC priorities can be configured to display which branch is successful (displayed) while all other branches failed (undisplay).

     Display rules and end condition priorities have their own pros and cons. The NCDOT Roadway ITL uses both methods. However, the usage of end condition priorities is favored more over display rules because it is more "automatic" and no expression needs to be written. Our end conditions actually start at the grass shoulder point.

     If the pavement underneath the shoulder berm gutter (SBG) needs to be shown differently from the pavement layers under the normal paved shoulder condition, then the SBG end condition can be configured to a priority of 1 and first seek the SBG style to find the location. If successful, then display the SBG as the "parent" component and any components associated with the SBG end condition (SBG pavement layers) and any components or any side slope end conditions attached to it are considered "child" components, will all get displayed. To do this, the main branch needs to start all the way near the centerline and branches outward. Under normal condition (seek SBG failed, no SBG graphic present) the normarl shoulder end condition will have a priority of 2. SBG and any child associated components also fails and undisplayed.

Component Parent to Child Relationship
     Along with display rules and end condition priorities, assigning a parent-to-child relationship to a group of components is another method to display or undisplay end conditions and components. A group of components and end conditions (children) can have an assigned parent component. Any changes affecting the parent component will also affect its children components. However, any change to the child component or end condition will not necessarily affect the parent component. For instance, a shoulder berm gutter (SBG) component can be the parent component for the three layers of pavement for paved shoulders with SBG (which is the a separate set of components for paved shoulder in a normal shoulder without SBG situation), the SBG guardrail, and the SBG end condition. If the SBG component is displayed or undisplayed, so will the children components. If the SBG component is deleted, then the children components are also deleted. If one of the child components gets deleted, it does not affect the parent component.

Assigning a parent component can be accomplished by editing the child component.