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Corridor Modeling Constraints

Using Template Constraints

The Create Parametric Constraint create constraint button and the Corridor Objects corridor objects button tool are found on the Corridor Modeling task menu. Use either tool to create a Constraint.

corridor objects dialog box
corridor modeling dialog box
constraint list

create parametric constraint dialog boxParametric Constraints or PC's have been defined to control almost every aspect or feature on the TC (Templates Corridor) Templates. Material depths, travel way, shoulder, cut and fill, widths and slopes as well as guardrail display and offset. These constraints are used to refine/define your design. You will use the constraints to transition your slopes from 2:1 - 4:1 - 6:1 as well as transition the roundings from 5 feet to 0 feet when going from a 4:1 fill to a 6:1 fill. Slope transitions should generally occur over 50 feet.

The LT and RT_EL_width's are defaulted to 0 offset from the CL but can be changed as above to create a turn lane or island.

When editing or creating multiple constraints using the Corridor Objects tool it is sometimes beneficial to use the Unlock - Activate Rule button unlock tool button. This allows you to create and edit constraints without each change or addition being processed. Reactivate the lock when done adding constraints, Close the tool then reprocess the corridor to have all the changes processed.

Constraints can be exported to a text file which can be edited and re-imported to create the constraints as shown here by copying the RT_EL_width constraints and editing them for the LT_EL_width.

pfe constraints

Some constraints control the display of template components like a switch thru display rules. The default value for RT_GR is -0.5, which has the Guardrail hidden. When the parametric constraint for RT_GR is set to positive (+) it turns on the display of the guardrail. LT_GR needs to be set to negative to turn it's display on.

The Dimension Height is another switch, by default it is set to -8. When the parametric constraint is set to positive it is turned on as well as being set at that height above the CL.

Some constraints like the LT & RT_EL_width can be set to 0, others which are used to extend and break slopes in superelevated areas like the LT and RT_Shldr_Break_width points should be set to a minimum offset of 0.005 so that the points slope property is still usable to create subsequent points.

Review Displaying Dynamic Cross Sections.

New Hampshire Department of Transportation
PO Box 483  |  7 Hazen Drive  |  
Concord, NH  |  03302-0483
Tel: 603.271.3734  |  Fax: 603.271.3914