Create Offset/Elevation Instructions

The Offset/Elevation instruction type defines a node based on the offset and elevation change relative to another node in the template. For example, you might create an "edge of pavement" Offset/Elevation node that has an offset of 5m at an elevation change of -40 cm relative to the alignment node.

Note: Because of the interdependent nature of template nodes, the instructions used to create the nodes must be in the correct sequence in the Instructions list. For example, you must add a node to the template before you can add another node that references that node for its location. The software builds the template step-by-step based on the sequence of the instructions.

To create a new Offset/Elevation template instruction:

Display the Edit Corridor Template command pane for the template for which you want to create a new Offset/Elevation instruction as described in Create Corridor Template Instructions.
If instructions are displayed in the Instructions section located beneath the template view, do the following. Otherwise, proceed to step 3.
1. In the Instructions list, select the instruction after or before which you want to insert the new instruction.
2. Click the Add Instruction button located at the top of the Edit Corridor Template command pane.
In the Instruction Type drop-down list, select Offset/Elevation.
In the Offset/elevation from drop-down list, select the node on which the offset and elevation for the new node will be based.
If you select <Previous Node>, the node created by the preceding instruction in the Instructions list is referenced. If there are no preceding instructions in the list, the node automatically created for the horizontal alignment is referenced.
Tip: You can also pick the 'from' node in the graphic pane of the template editor. To make the locations of nodes more obvious, select Options > Show node labels at the bottom of the editor.
Click the Offset button and select the appropriate offset type for the new node:
- Offset - Enter the offset distance between the Offset/elevation from node and the new node. Include a minus sign to indicate an offset to the left of the Offset/elevation from node. Or, click in the Plan View or template view to select the offset distance.
- Node to node - Select the node combination in the drop-down lists that provides the distance you want to use for the offset between the Offset/elevation from node and the new node. Or, select the nodes in the template view.
  The order of the nodes you select determines whether the offset is negative (extending to the left of the reference node) or positive (extending to the right of the reference node). If the first node you select is located to the left of the second node you select, the offset for the new node will be positive. If the first node you select is located to the right of the second node you select, the offset for the new node will be negative.
- Table - Click the More button to display the Edit Table dialog. Then specify the offset between the Offset/elevation node and the new node at each station in the corridor from the current template to the next template (or the end of the corridor).
  You can type the station in the Station field, or you can select it in the Plan View.
  In the Offset field, click the button to select between entering an offset distance or referencing a 2D line for the offset. If you select to enter an offset distance, you can either type in the distance or select it in the Plan View or template view. If you select to reference a 2D line, you can select the line in the Plan View or select the node representing the line in the template view.
- 2D line - Click in the field next to the Offset button. Then, select the line in the Plan View on which you want to base the offset, or select the node representing the line in the template view. The new node will use the same offset from the Offset/elevation from node as does the 2D line.
Click the Elevation button and select the appropriate elevation type for the new node:
- Delta elevation - Enter the difference between the Offset/elevation from node and the new node. Or, select the distance whose value you want to use for the delta elevation in the Plan View or template view.
- Elevation - Enter the actual elevation of the new node, select a point in the Plan View whose elevation you want to use, or select an elevation in the template view.
- Node to node - Select the node combination in the drop-down lists that provides the delta elevation you want to use to specify the elevation from the Offset/elevation from node to the new node. Or, select the nodes in the template view.
  The order of the nodes you select determines whether the slope is negative (sloping down from the reference node) or positive (sloping up from the reference node). If the first node you select is higher than the second node you select, the slope for the new node will be negative. If the first node you select is lower than the second node you select, the slope for the new node will be positive.
- Delta elevation table - Click the More button to display the Edit Table dialog. Then specify the difference between the Offset/elevation from node and the new node at each station in the corridor from the current template to the next template (or the end of the corridor).
  You can type the station in the Station field, or you can select it in the Plan View. You can type the delta value in the Delta Elevation field, or select the distance whose value you want to use for the delta elevation in the Plan View or template view.
- Elevation table - Click the More button to display the Edit Table dialog. Then specify the actual elevation for the new node at each station in the corridor from the current template to the next template (or the end of the corridor).
  You can type the station in the Station field, or you can select it in the Plan View. You can type the elevation in the Elevation field, select a point in the Plan View whose elevation you want to use, or select an elevation in the template view.
In the Name drop-down list, select the name you want to use for the new node. Or, type in a new template node name. Selecting or entering a template node name is optional. For additional information, see Create, Edit, and Delete Template Node Names.
If you plan to connect this corridor to one or more intersections and/or cul-de-sacs, select lane properties in the Type of code above list:
- Lane edge - Select this for an instruction that ends with an edge of pavement (EoP) node. It can then be used to connect to a corresponding lane edge node automatically generated in an intersection or cul-de-sac.
- Shoulder - Select this for an instruction that ends with an edge of shoulder node. It can then be used to connect to a corresponding shoulder node automatically generated in an intersection or cul-de-sac.
In the Material layers list, check boxes for the material layers on which you want the line segment created by the instruction to appear. Selecting a layer is optional. However, if you do not select a layer, no line segment is created. (Corridor line segments are displayed in the Plan View and 3D View. If you export the corridor, they are used to create the exported corridor surface.) For additional information on material layers, see Understanding Corridor Material Layers and Corridor Surfaces and Create, Edit, and Delete Material Layers.
If you have any of the boxes for subgrades checked in the Material layers group, the Material above list is enabled. Select a pre-defined material as the material above the instruction that you are editing, or select <New> to open the Material and Site Improvement Manager where you can define materials. If shrinkage, bulkage, or compaction factors have been specified for an earthen material, they will be used in any corridor volume calculations.
Note: For other instruction types, it the instruction is not assigned to a material layer, you cannot assign a Material Above. This does not apply to the Offset/Elevation instruction, however; you can assign the material and it is applied to the area where the offset/elevation node is computed. If that area already has a material assigned, then this instruction is ignored.
Note: The use of material layers requires a license. See the Subscription Plans page. For a license matrix by command, see the License page in the TBC Community. Also see View and manage licensed features.
If you want to specify rollover parameters for the new node, do the following:
Note: Rollover parameters can be applied to a superelevated curve to ensure that slope differences between segments (for example, a driving lane and a shoulder) are kept to a minimum for safety and comfort at design speed.
1. Check the Define rollover parameters check box. The Maximum delta field and Minimum delta field display.
2. In the Maximum delta field, enter a positive number (from 0 through 20) for the maximum slope percent the segment created by the new node can vary from the segment created by the Offset/elevation from node. This is typically applicable to the outside lane and shoulder of a superelevated segment.
  The value entered in the Maximum delta field must be the same or greater than the number entered in the Minimum delta field.
  For an example of how this parameter works, see Rollover Parameter Examples.
3. In the Minimum delta field, enter a number (from -20 through 20) for the minimum slope percent the segment created by the new node can vary from the segment created by the Offset/elevation from node. This is typically applicable to the inside lane and shoulder of a superelevated segment.
  A positive number specifies that the slope for the new node will be downward from the slope for the previous node (typical for drainage). A negative number specifies that the slope for the new node will be upward from the slope for the previous node (not typical).
  The value entered in the Minimum delta field must be the same or less than the number entered in the Maximum delta field.
  For an example of how this parameter works, see Rollover Parameter Examples.
To turn off default transition logic that might, for example, connect a node in one corridor template to an incorrect node on the next template, uncheck the Transition allowed box.
Note: The default logic may be incorrect in rare cases in which templates are complex or far apart. Unchecking this box lets you define such transitions manually instead (using a table of values when adding instructions). In TBC versions before 5.70, any value type that was defined over a station range was never interpolated. So tables do not use this checkbox. Only constant values, such as an offset going from 10 units to 20 units between templates, are interpolated.
Do one of the following:
- Click the Add After buttonto insert the new instruction after the selected instruction in the Instructions list.
- Click the Add Before buttonto insert the new instruction before the selected instruction in the Instructions list.
  Note: If there are no instructions in the Instructions list, click either button to insert the new instruction as the first instruction in the list.

The new instruction is inserted into the Instruction list. The new node and line segment (if created) are displayed in the template view. The fields are cleared and you can repeat this procedure to create and add more instructions to the template.

Note: Once you have created corridor template instructions for one side of a corridor centerline, you can use the Mirror Instructions command button (located at the top of the Edit Corridor Template pane) to copy them to the other side of the centerline with reversed offsets. This can save you time and help you avoid errors when creating a corridor template. See Mirror Corridor Template Instructions for more information.