Terrain edit surface driving me nuts

[Anonymous]

hello all,
i am having a problem when editing an existing surface using land desktop companion 2008. the surface is a large area, 12,000 feet by 3500 feet, with the survey line running west to east every 500 feet. the surface is along a beach, with about 500 feet upland and 3000 feet submerged, so the elevations range +16 feet to -30 feet. the surface is created and built using survey points. then we start to clean it up. everything starts out fine for editing. editing the surface we use only the commands under TERRAIN > EDIT SURFACE or the edit surface tool bar. we save the surface frequently and re-import the 3d lines to refresh the view. then the problem starts, i choose add surface line, to change where the breaklines fall. normally, i would connect 2 points and whatever existing lines were there, they would be replaced by the new line and other new lines would be created by terrain to match the line i just created. now when i "add line", if i cross over say 4 existing terrain lines, instead of erasing them, it break those existing lines where the new line crosses and creates a surface point where one should not be created. we use "flip face" whenever possible, and it helps, but will not work in every situation.

this has been happening on 2 separate computers.
both have:
xp sp3 (this also happened on both computers when they had sp2)
civil 3d 2008
land desktop companion 2008

computer "a"
intel core 2
2.4 ghz
4 gigs ram

computer "b"
intel pentium 4
3.4 ghz
4 gigs ram

[Jeff_M]

Rather than " i choose add surface line, to change where the breaklines fall." you will likely get better results by drawing a polyline along the breakline(s) and adding these to the surface as breaklines. This usually results in far fewer manual edits being required.

I'm not sure why adding lines is creating the additional points...I don't recall seeing that issue before (but it's been 4 years since I've used LDT in production, so my memories of it are fading). I do know that problems arise when you end up with edits crossing previous edits.