When you change a span length, modifications made to the affected span(s) are removed; for example, structures and terrain features. There are three cases in Overhead Design Analysis (OHDA) that allow a span length to change and, therefore, result in removal of these span features.
Change Span Length on the Profile Tab
Changing a span length on the Profile tab can have effects you do not anticipate. If there is a span after the span you modify, changing the first span modifies the span length for both spans because the change that modifies the first span is added or subtracted from the following span. For example, consider a profile that consists of two spans of 200 feet each for a total of 400 feet.
When you change the first span to 150 feet, the following span automatically changes to 250 feet to keep the total profile length at 400 feet. Both spans have changed, so any structures and terrain features are removed. Notice that the base surface type remains.
Add a Pole Between Existing Poles
You may have a span that includes structures and terrain features, and you need to add a pole in the middle.
When you add a pole between existing poles, it affects the span length by splitting it between two spans. This action also removes any structures and terrain features that were in the original span, but the base surface type remains.
Change Line Angle of a Pole Without Including Downstream Poles
Changing the line angle of a pole affects the placement of the next pole in the profile, but it does not change the length of the span between the two poles because the downstream pole remains the same distance from the pole that was changed. In this situation, structures and terrain features are rotated along with the line angle. However, if downstream poles are not included in the angle modification, the pole that is downstream from the rotated pole does not change positions. This causes the span between the rotated pole and the next downstream pole to change, resulting in the removal of structures and terrian features from that span.
