Create or Edit Horizontal Design Parameters

Description

Create or edit a horizontal design parameter set.

Access

Alignment / Design / Design Parameters Parameters / Horizontal / Insert new items or Copy items or Edit items

Requirements

Design module

Controls

Control	Description
Name	Type the name for the design parameter set.
Description	Type a description for the design parameter set.
	Insert a new line in the design parameter set.
	Delete selected rows from the design parameter set.

Parameter List

The columns displayed are dependent on the horizontal design parameter selected:

Column	Description
Velocity	Type the design speed for which the parameter is applicable in the project velocity units.
Deflection Angle	Type the maximum deflection angle allowed at intersection points at the specified design speed, before a curve must be fitted.
Side Friction	Type the maximum allowable coefficient of side friction between the vehicle and the road at the specified design speed.
Superelevation	Type the maximum superelevation at the specified design speed. Note: Type the value in the project grade units and the project angular units if the grade units are configured to 'Angle'.
Minimum Curve Length	Type the minimum curve length required at the specified design speed. Note: For combined curve this length includes both transition curve and the circular curve.
Transition Length	Type the minimum transition length at the design speed to build up the superelevation at an acceptable rate. Note: If a transition curve is not required at the design speed, configure the minimum length to zero. When the curve computation in the standard is configured to maximum, this parameter table is also used to determine the radius of the combined curves.
Maximum Radius	Type the radius of the computed circular curve where transitions are no longer required.

Notes

Insert a row for each design velocity then type the acceptable parameter for the design velocity.
Click OK to accept the parameter set and apply the parameters to existing alignments that use the design parameter set.
Configure the angular units, grade units and velocity units in the unit options.
Use the Import Configuration tool, to import a horizontal design standard into an existing project or template.

Possible errors

Warning

Description

One or more alignment curves could not be computed. Use the Horizontal Intersection Point dialog to resolve these cases.

You have edited a design parameter table that is already in use by at least one alignment. A curve that abides by the new design parameters cannot be created at at least one intersection point. On the Alignment tab, click

then select Horizontal and examine the intersection points with the curve type highlighted red. You can adjust the design velocity, the parameters or the alignment vertices so that your design parameters are suitable. Alternatively you can choose to override the automatic curve generation at the intersection point and select a different method for creating the curve.