Expand string by berm width

You can use this function to expand all segments of a selected string by a fixed berm width, using a gradient to increase the elevation of each berm if you wish. Similarly, you can use this function to contract the segments by a fixed berm width.

Prerequisites: A string is open in Graphics.

To run this function: Choose Design > Expand string > By berm width, or...

In the Function Chooser, type EXPAND STRING BY BERM WIDTH, and press ENTER.

You can make berm creation conditional on the difference in elevation to a target elevation or DTM surface. Conditional berm creation allows you to create a berm of the desired width in locations where the berm is required, and a berm of zero width in locations where the berm is not required, resulting in no berm for a portion of the berm length.

Note: This function works on both open and closed segments of the selected string.

Fields on the Expand String by Berm Width form

Field	Description
String	Display only. The string number of the selected string.
Minimum Z value	Display only. The minimum Z value of the selected string.
Maximum Z value	Display only. The maximum Z value of the selected string.
Define the method of expansion
Berm creation method	When creating a berm, you can choose to create a berm of the required width along the full length of the selected string, or only where the difference in elevation from each point on the selected string to a target elevation or DTM meets some criteria. Berm creation method allows you to create the berm under circumstances which are normal when excavating a pit. For example, in a pit where berms are required at 10 metre vertical intervals, when the pit walls are close to the ground surface, it may be desirable to create berms only where the difference in elevation from the nominal berm elevation to the ground surface exceeds 3 metres. The berm creation method provides this flexibility by providing berm creation options that depend on the difference in elevation from the berm elevation to either a target elevation or to a DTM surface. Note: For those berm creation alternatives which relate to a DTM surface, it is a prerequisite that you have previously loaded the DTM surface of interest using the LOAD DTM SURFACE function. The following list explains when a berm of the required width is created at each point of the segment. always. always delta z to elevation >=. only if the absolute value of the difference in elevation from the point to the target elevation is greater than or equal to Delta Z limit. delta z up to elevation >=. only if the point is below the target elevation and if the difference in elevation from the point to the target elevation is greater than or equal to Delta Z limit. delta z down to elevation >=. only if the point is above the target elevation and if the difference in elevation from the point to the target elevation is greater than or equal to Delta Z limit.. delta z to elevation <=. only if the absolute value of the difference in elevation from the point to the target elevation is less than or equal to Delta Z limit delta z up to elevation <=. only if the point is below the target elevation and if the difference in elevation from the point to the target elevation is less than or equal to Delta Z limit. delta z down to elevation <=. only if the point is above the target elevation and if the difference in elevation from the point to the target elevation is less than or equal to Delta Z limit. delta z to dtm >=. only if the absolute value of the difference in elevation from the point to the DTM surface is greater than or equal to Delta Z limit. delta z up to dtm >=. only if the point is below the DTM surface and if the difference in elevation from the point to the DTM surface is greater than or equal to Delta Z limit. delta z down to dtm >=. only if the point is above the DTM surface and if the difference in elevation from the point to the DTM surface is greater than or equal to Delta Z limit. delta z to dtm <=. only if the absolute value of the difference in elevation from the point to DTM surface is less than or equal to Delta Z limit. delta z up to dtm <=. only if the point is below the DTM surface and if the difference in elevation from the point to the DTM surface is less than or equal to Delta Z limit. delta z down to dtm <=. only if the point is above the DTM surface and if the difference in elevation from the point to the DTM surface is less than or equal to Delta Z limit.
Delta Z limit	If you choose a berm creation method that is dependent on the difference in elevation to a target elevation, or DTM surface, Delta Z limit is used to determine whether or not to create the berm.
Limiting elevation	The target elevation to use as the controlling feature for conditional berm creation if you choose a Berm creation method that relates to a target elevation.
Berm width method	The method used to determine the berm width. Options are; fixed width: The berm width is defined in the Default berm width field. descriptions: The berm width is taken from the D2 field of each point in the string. Note: If any point in a string has a non-numeric value, or no value, in the D2 field, the default berm width is used. slope strings: The berm width is determined by one or more slope strings. Note: To use this method you must load the slope strings. If any point in the string is not inside the slope strings, the default berm width is used. block model: The berm width for each point is determined by an attribute stored for the block that contains the point, in a loaded block model. The attribute is defined in the Berm width attribute field. Note: This option is available only if a block model is loaded. If any point in the string is outside the extents of the block model, the background value of the attribute is used.
Berm width attribute	The attribute, in the loaded block model, that defines the berm width method. Note: This field is active only if a block model is loaded and you have selected block model for the Berm width method.
Default berm width	The berm width to use for expanding the segments if the berm width method is fixed width, or if the berm width is otherwise undefined.
Berm gradient (%)	You can use a crossfall gradient to ensure appropriate drainage on the berm. The gradient is expressed as a percentage. A positive value causes an increase in elevation from the selected string to the new string. A negative value causes a decrease in elevation from the selected string to the new string.
Horizontal direction	expand: The selected string is expanded to create the new string. contract: The selected string is contracted to create the new string.

Output

A new string is created, with a string number that is one greater than the string selected. All segments of the selected string are copied and modified according the parameters you specified in the form. The new segments are displayed in Graphics. Any loops that form as a result of contracting portions of the segments are removed.

Note: When you use this function to create berms that intersect, the crossover that is created at one of the ramp edges, prevents you from using GRAPHICS CREATE DTM. To resolve this problem, you can manually remove the point that is causing the error.

Expand string by berm width

Fields on the Expand String by Berm Width form

Output

Troubleshooting