About the only time I see them are as break lines inserted to contain features that might have been blown over during design. Files from engineers are usually not loaded with these lines. 3D lines vary in elevation and are the best way to create curbs and other road and parking lot features. 3D LinesĬontours have one elevation their entire length. However, this can become a problem when there is not much dirt to move, and crews need more exact information. One can argue that it is just a starter file, and this is too much detail. The problem can spike when elevations do not match between contours and 3D lines. Any of the three lines that make up the road, (edge of pavement, face of curb, and top back of curb) can be drawn and then offset to get things closer.The straight segments created by the function can cause crossing line and new headaches. Edge of pavement CAD lines can sometimes be elevated as they cross the contours.There are no real easy ways out of the issue except to connect them with 3D lines. The triangles will link in a bad way and make a surface that not only looks bad but does not perform. In this image the problem is with roadway contours. The problem is they take time to draw and auto functions can make the cleanup harder than just connecting the dots yourself. Linking contours with break lines can solve some issues.That may be fine for a new subdivision road but not for a rehab project or lane additions those are usually close to grade to start, and you may make a bigger mess doing a quick surface. At the right is a mess that should be a nice retention area.You need to go through the model and see if each high and low area look good. Ditches and berms are easily flattened and there is no simple way to verify their existence.You will not get detail to get you within a half-foot, do not even try. At some point, you need to decide what a contour only surface should have. Here is a screen shot of the improved density and some spike removal. A ditch is being blown over and slopes are not smooth and even. It needs break lines in order to make sense.Some areas have long runs without anything and it is too dense in other spots. This may be considered work that takes too long for a quick start, but the spikes and bad information will cause more issues than they fix. In this case we cannot send this out, work needs to be done. You need to trust me they are a decent representation of the surface.Ĭreating a quick surface shows there are some problems. Initially, these contours do not look so bad. Contours undergo a lot of changes during data production but are often a quick way to get something out. ContoursĬontours are referred to as 2D lines because they are all the same elevation and still 3D because they are part of a surface. I will go through the advantages of each data type for a quick surface and what they do (alone or with other elements) to get you moving. Surfaces can be any combination of these three things. When I talk about a surface, we are looking at the 3D elements that are elevated to make a model, contours, 3D lines, and points. I am speaking of the people in the office who get the call four minutes after the CAD files hit everyone’s inbox and the voice on the other end is wondering where the model is. My hat’s off to you, most jobs do not get enough warning to make them pretty from the start. When someone finally gets the files, and crews have been on the job for three weeks, a quick (and very dirty) surface turned around overnight is better than nothing.Įverybody talks about only sending out “perfect” models. From a time-management standpoint, we can build a surface faster than the time it takes to break it apart, find the issues, and put it back together. We never use an engineer’s surface sent with CAD files because we are being paid to build it correctly. There are many reasons you may be compelled to do a quick fix on a bad surface and get it in the field.