Option

Description

Use Design Criteria

Select this checkbox to use design criteria during the road design process.

Design Speed

Select the design to be used for the current project.

Vertical Settings

Grade Pen

Click to select the pen colour in which grade envelopes should be drawn.

Terrain Type

Select the type of terrain through which the vertical alignment is being applied.

Curve Type

Specify whether the vertical curves must have a parabola or circular shape. This setting is stored in the roads file. Therefore, each road will have its own curve type setting.

Superelevation Settings

Crossfall at straights

Enter the superelevation rate for straights for each side/carriageway.

Super Settings

Click to display the Super Settings. The label indicates which formula is being used, as specified in the Super Settings dialog.

Super Graph

Click to display the Superelevation rates graph.

Save As button

Click to save the settings to a *.vdc, design criteria file.

Load button

Click to load a *.vdc, design criteria file. You can load a file with the UK standards from our "Example" folder.

Restore Defaults button

Click to restore the contents of the spreadsheets to the TRH or UK standards. The following dialog box displays.

 confirmation message displays.

Option

Description

Speed

The design speed increments can be altered by double-clicking in the appropriate row header.

Min Radius

Enter the minimum curve radius per design speed.

Min Curve Len

Enter the minimum radial curve length per design speed.

Max Curve Len

Enter the maximum radial curve length.

Small Deflection Limit (deg)

For deflection angles less than this value, the minimum length of the curve specified in the Min Curve Len column, will be increased by Increment for each 1 degree decrease in the deflection angle.

Increment

Enter the increment by which the minimum curve length will be increased, for each degree less than the Small Deflection Limit.

Compound Crv Max R1/R2

Enter the maximum radius-ratio for compound curves. Flatter curve radius divided by the sharper curve radius.

Min Tangent Length

Enter the minimum tangent length for broken-back curves. Two successive curves will not be recognized as broken-back curves if the tangent is greater than 500 m.

Tr Curves For R <

Enter the radius that the program will use when deciding whether transition curves will be used or not. Transition curves will be used if the horizontal radii are less than these values.

Max Tr. Len (X*R) ^0.5

Enter the value of X in this column (X*R)0.5. Transition curves lengths may not be greater than the values calculated by this formula.

Option

Description

Min K Crest

Enter the minimum K value for crest vertical curves at this design speed.

Min K Sag

Enter the minimum K value for sag vertical curves at this design speed.

Min Len

Enter the minimum length of any vertical curve at this design speed.

Max Grade Flat

Enter the maximum grade between VPI's in flat terrain at this design speed.

 Max Grade Rolling

Enter the maximum grade between VPI's in rolling terrain at this design speed.

Max Grade Mountainous

Enter the maximum grade between VPI's in mountainous terrain at this design speed.

Option

Description

Slope Factor

Enter the relative slope factor for the relative design speed (s).

Min Runoff

Enter the length of superelevation run-off per design speed (L).

Max Super

Enter the maximum superelevation value. This is the largest superelevation value that will be used.

Compound curve L

If the length of the first circular curve (CT) of a compound curve pair is less than this value, Case 1 will be applied, otherwise Case 2 will be applied. These cases are explained in the design process.

Broken Back Max Tangent

Two consecutive curves with a common tangent of less than the value specified in this column, will be considered a broken-back curve. See design process.