InRoads - Generate Front/Top of Curb Feature

[Crystalct1]

Here's the issue: Our surveyors, and most I've worked with, bring back survey for curbs by giving two lines: one represents the gutter line, one represents the back of curb. Assuming the front of curb is the same elevation as the back of curb, I always have to generate another offset feature for the front of curb so that the curbs are shaped correctly in cross-section. Seems easy enough. Generate longitudinal feature using the back of curb feature as the reference and primary with offset/offset setting. Use about 0.7 or so for the horizontal, and 0 for the vertical.

Problem is that the original surveyed linework never seems to be consistently parallel to one another. This means that I end up with a front of curb feature that is overhanging the gutter in some places and a little too far away in others, giving more of a slope on the front curb face than I find acceptable. What I would like to do is to use the gutter line as the primary feature so I can follow IT by 0.05 or so instead of the back of curb line. But there is no way to use the elevations from the back of curb feature while using the gutter feature as the primary feature. Is there?

Has anyone a better solution than just manually editing all the overhangs?

 

[mechamb]

Crystalct1, I have always used the flowline feature as the offset line. I go over in the horizontal 0.05 and then whatever the vertical is 0.5 that way you are less likely to have the crossing breaklines.

HTH,
Bob Mecham

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[Crystalct1]

mechamb, the problem I have with what you suggested is that I do not want the top of curb feature to be 0.5 higher in elevation than the gutter. This is not accurate; this is an estimate of something for which have surveyed data...Defeats the purpose, doesn't it? The surveyor has given me a back of curb feature whose elevations are true. I want those elevations to be the same elevations on the front of curb feature. So, I am looking for a way to generate a feature that is 0.05 horizontally offset from the gutter line, but uses the exact same elevations as the actual surveyed back of curb feature. This is a job for generate longitudinal feature (GLF), but with which controls? I want a feature that is offset horizontally from one feature, using the elevations from another? I STILL find it odd that Bentley has no tool that does this simply.

Here's what I decided to do:

First generate a graphic-only line, GLF at 0.05 offset horizontally from the gutter line, vertical control at any constant elevation - I use 0 so when I view it isometrically, this graphic is far away from the actual features.

Then generate another graphic-only line, using GLF at 2 feet horizontal offset from the back of curb feature, with vertical control transverse slope of 0%. (It doesn't have to be 2 feet, just has to be enough so that it is in front of the gutter line, in the street somewhere).

For both of these graphics, the exterior arc setting is left at the default of 5^, so that any "curves" in the features will be adequately replicated in the generated graphics. And I use graphics-only, because I just need temporary graphics to set slopes and positioning. Of course, this means that your locate lock will have to be set to graphics as opposed to features in order to use the temporary graphics as controls.

Lastly, turn off the "graphics-only" setting to create the front of curb feature. Using GLF with horizontal control "along selected feature" and vertical control as "project slope", generate a perfect front of curb using four inputs: (1) the back of curb feature as the primary element, (2) the graphic-only line (the one in the street somewhere) as the secondary element, (3) the graphic-only line that is 0.05 away from gutter as the selected horizontal feature, and (4) the back of curb feature as the reference element.

A few interesting tidbits: For the generation of the actual feature, I have found that the reference feature interval should be set to about 5 and stroke tolerance at about 0.04, just in case the gutter line has been defined by more points than the back of curb. This is important because it is better to use the back of curb (and not the gutter line graphic) as the reference feature. Using the back of curb as the reference feature, the generated feature will duplicate the amount of points on the back of curb, and that USUALLY works out fine, without increasing the interval. On the other hand, if you use the 0.05 offset graphic as the reference feature, it will copy the amount of points on the gutter, which looks great horizontally, but you encounter vertical problems in the area of a depressed curb (DC). By not using the back of curb as the reference feature, you run the risk of not picking up those differences in elevations at the DC. So, use the back of curb as the reference, but the interval must be increased because if there are "curves" in the gutter feature (like around corners) and the back of curb points are not as dense in the area, you run the risk of the new feature not having enough points to remain parallel with the gutter and stay ALONG the generated graphic at 0.05. Crazy! But yes, you'll request ALONG SELECTED FEATURE and in some cases, it will NOT be along the selected feature if you don't increase the reference feature interval. And then, you'll end up with the same problem we were originally trying to avoid - crossing features.

Then all you do is delete your temporary graphics with a couple of clicks, with MicroStation graphic group lock on, so that all points and anything generated by feature styles gets deleted at once.

This absolutely takes a LOT longer to explain than to do. Also, I have saved the preferences for each of the three uses of GLF above, which helps too. Maybe I am just anal, but what I end up with looks 100% better than anything else I've ever seen from anyone. My surveyors do not give me a back of curb feature that is even close to parallel to the gutter, so I cannot just horizontally offset that feature by any number - it will either cross in front of the curb, or end up giving me a too-much slanted front curb face in cross-section.

Or maybe I am just totally missing a simpler way to do this?

 

[Crystalct1]

I subsequently realized that the creation of the temporary graphic offset at 3 feet into the street is unnecessary. If you simply use the back of curb feature as the primary and secondary, InRoads knows what to do. It doesn't need them to be two separate items. And it is cleaner with the single item. Occasionally, I was getting a tiny 0.01 or so difference in elevation in the resulting feature. I guess because as it would project between vertices across the back of curb feature and the 3-foot offset graphic, a small amount of interpolation was introduced. No big deal, but it bothered me because I felt like it should be exactly the same elevation as the feature generated at the back. Using the single item eliminates this "glitch".