Expand segment by berm width

You use this function to make a copy of a selected segment and expand or contract it by a fixed berm width. You can use a gradient to increase, or decrease, the elevation of each berm if you wish.

Prerequisites: A segment is displayed in Graphics.

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

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

You can make berm creation conditional on the difference in elevation to a limiting elevation or to a 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, so that there is no berm for a portion of the berm length.

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

When you run this function the following message is displayed:

Select the segment to be expanded

In Graphics select the string to expand.

Fields on the Expand Segment by Berm Width form

Field	Description
String	Display only. The string number of the selected string.
Segment	Display only. The segment 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 limiting elevation or DTM meets specific criteria. For example, in a pit where berms are required at 10 metre vertical intervals, when the pit walls are close to the ground, you might want to create berms only where the difference in elevation from the nominal berm elevation to the ground surface exceeds 3 metres. Note: For those berm creation alternatives which relate to a DTM surface, it is a prerequisite that you have previously loaded the DTM surface 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 Limiting elevation is greater than or equal to Delta Z limit. delta z up to elevation >=. only if the point is below the Limiting elevation and if the difference in elevation from the point to the Limiting elevation is greater than or equal to Delta Z limit. delta z down to elevation >=. only if the point is above the Limiting elevation and if the difference in elevation from the point to the Limiting 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 Limiting elevation is less than or equal to Delta Z limit. delta z up to elevation <=. only if the point is below the Limiting elevation and if the difference in elevation from the point to the Limiting elevation is less than or equal to Delta Z limit delta z down to elevation <=. only if the point is above the Limiting elevation and if the difference in elevation from the point to the Limiting 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 creating the berm is dependent on the difference in elevation to a limiting elevation, or DTM surface, this function uses Delta Z limit 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 uses a limiting 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 segment. Note: If any point in a segment 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 segment 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 segment is outside the extents of the block model, the background value of the attribute is used.
Berm width attribute	The attribute, present in the connected block model, that defines the berm width method. Note: This field is active only if a block model is connected 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 segment is expanded to create the new segment. contract: The selected segment is contracted to create the new segment.
Switchback characteristics
Add switchback	Selected: A switchback is added to the ramp. Cleared: No switchback is added to the ramp.
Ramp name	Display only. The names of the ramps on the segment being expanded.
Switchback angle	The angle, in decimal degrees, that the switchback will turn.
Switchback inner radius	The radius of the inner part of the curve of the switchback. By minimising this value, you can minimise the excavation volume.

Output

A new segment is created, with a segment number that is one number higher than the string number of the selected segment. The parameters you entered determine the coordinates of each point on the segment. The new segment is displayed in Graphics. Any loops that formed as a result of contracting portions of the segment are removed. If you selected to add a switchback to any of the ramps in the segment, the switchback is created with the angle and radius you specified.

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.

Troubleshooting

Message	Description
`String xxx, segment xxx, point xxx is a spike`	Spikes or foldbacks have been found in the segment being expanded. The new segment is not created. A marker is displayed at the point where the spike was found so that you can correct the problem.
The point selected is not in the working layer and cannot be edited.	This function is available only when the selected segment is in the active layer.