When building sidewalks and parking lots, creating accessible curb cuts can be done by creating a custom loadable void family.
- [Instructor] A very common requirement in any sort of sidewalk or parking lot is to have accessible ramped areas for wheelchair access. And, in order to model those, there's a few different techniques that you can use. So if you watched last week's tip, then you saw that I used the technique that's over here on the right of my screen where I actually used the shape editing tools on the floor element and then just simply moved those points in the Z direction to create that curb cut directly in the floor element in (mumbling) as part of the floor element.
But there's another technique that you can use instead and that's to create a loadable family that will have a void inside of it and that void will cut away from the floor slab achieving essentially the same thing. But in a family that you can use in multiple locations. So, the nice advantage of the family approach is you only need to build one of these and then you can use it like any other family in any project, or in any situation. So it's a little bit more flexible than having to build it each time you need it. So, in this video, I want to show you how this family was built.
Now, actually, we're not going to build this one. This one here, if we look down at my status bar I just simply select it and show you the name right here, you'll see that it's called curb cut tree. So my first attempt at doing this I was trying to build the void along the slope of the ramp. And that meant that I had all these very slight angles to deal with and therefore, I was getting into a lot of trigonometry in order to calculate how to build that void. And, as you can see, it worked. It's quite acceptable as a curb cut ramp. But, it's just a little bit more complicated of a family.
Well then it dawned on me that if I just thought of it a little bit differently then I didn't need to use trigonometry at all. What I could do instead, is just use a blend and build it vertically as a blended element and it greatly simplifies what's required to build that family. So that's the one I'm going to build with you here today because I, in the end, I like that solution better. So, I'm going to switch over to that file that I've gotten started. And I've called it curb but blend void. And this is a face based family. So if you were going to build this from scratch you would go to new, and family.
And then you would choose the face based generic model template. Which is, this one right here. Now, it's possible to also use the floor based template, it looks kind of the same. The difference is this one would require a floor host where the face based is a little bit more flexible because you can actually use it on any type of element. So, most of the time it's going to be a floor but I just want to keep it as flexible as possible so I went with face based. But it's entirely up to you. So I'm going to do the rest of the work here in the floor plan.
So there's a rough level floor plan. And, I'm going to try not to repeat too much of what we did in last week's tip. So I'll just sort of summarize. I've got essentially the same reference planes here that I had in that starter file, as well. So, down here right at the edge of this extrusion element I have a reference plane that I called edge. Up here, I have another one that I've called buffer area. So the distance between those two reference planes is the length of my ramp.
I've created a parameter here called ramp length for that purpose. Then I've got another reference plane back here for the sidewalk width. And I just put that in here even though that's not going to be driving any geometry. So it's just sort of there for reference. Okay, so there's my sidewalk depth back there. Then I've got the right flare and the left flare right here. And of course, those are being calculated at a different slope than the ramp is. So, I have a different formula driving those. And then of course, I've got the ramp width.
Now one of the advantages of doing this as a family is, all of these parameters can be flexed. Ramp length, ramp width, and flare. If I open family types and show you some of these you can see that my curb height is currently .5. I've set the units of this family to feet. Decimal feet. But, it is feet, so .5 feet or six inches is the height of my curb. I've got my sidewalk size at five feet. My ramp width at four feet. And then notice that my flare and ramp length are being calculated.
They're being calculated by taking the slope and multiplying that by the curb height. So, here's the slope of 10% for the flare and 8.33% for the ramp. Now I prefer to see those slopes in percentages. And, the way that I did that and the way that I set this file to decimal feet was to go to manage. Click on project units. For length, I simply chose decimal feet and a custom number of decimal places. And, for slope, I changed it to percentage at three decimal places.
Now, it really doesn't matter what unit format you use. It's just a matter of how it formats it on screen. So it's really a matter of your personal preference. So, all of that establishes the reference planes which is the overall shape of the ramp curb cut. So all that we have to do now is build the blend. So, to build the blend, I'll go to Create. And if I take you to the front view I've got a reference plane down here called bottom. That's where I'm going to draw this blend. So, back to the floor plan.
Go to Create. Click the blend. And I want to click the set button here and make sure that my reference plane bottom is my current work plane. I'll click Okay. So I'm drawing the bottom surface of the blend. Now, ideally, I would want it to be just a line across here, but you can't do just a 2D line. It's got to be a shape because we're creating a solid element. So, that's why I created this reference plane out here. Now, I just lock that one a few inches away just to give me that long thin rectangle.
So here's the long thin rectangle that I'm going to draw. From here to there. And I'll just lock that all the way around. Click the modify tool. So this distance here is arbitrary. It's not really important. But of course, the width is being determined by the ramp width. Now I'm going to click edit top. And here's the shape that does matter because this is the shape of the flared ramp. So I'm going to stick with the line tool here. And just snap to the inner sections of the various reference planes that I've drawn.
Now, that's the basic shape that I need. But I want to make sure that it moves and flexes with those reference planes when we change any of the parameters. So I'm going to go to my align command. Pick this reference plane. And lock that line to it. This reference plane here called edge and lock that line to it. Now, it's really important that you pick the reference plane and not the edge of the slab. Okay, so make sure it says reference plane there. And then I also want to make sure that I'm doing the end points of these diagonal lines.
So there, there, there, and there. And that will ensure that everything flexes the way we expect as any of those dimensions vary. Now when I click Finish it will create the blend form. And, the best way to see that is in 3D. And we still have two issues to contend with. The first is, the blend is too tall. So as you can see, it's popping up above the surface of the floor slab. So that's because the default blend, the thickness, is just one foot.
Well I'm going to click the small little associate family parameter button right here for the second end. And associate that with the curb height parameter. Therefore, whatever height we make the height of the curb this void will always match that height. So that takes care of that. And then all we need to do is take this solid blend and turn it into a void. Now, before I do that, I just want to comment on one last thing. That little thin rectangle that I did at the front was simply because, if you recall, I really wanted to just have a line there.
But, I just made it over hang the edge. So you could see that this little wedge piece that over hangs the edge will be inconsequential it won't affect the shape of our ramp at all when we finish it. So, I've got this selected. I'll scroll down here. And instead of a solid, I'll change it to a void. Then I'll click cut geometry. Select the extrusion. And then the void. And then that completes my curb cut shape. Now, one last thing.
Back to reference level floor plan. And this edge reference plane right here if we scroll down in the properties I've defined that as the origin for this family. Now I left the center reference plane in this direction as the origin, which means that the insertion point is right there at the intersection between those two reference planes. So let's test it out. Let's click load into project. That takes me back to my curb cut project that we were working in before.
And, it defaults to place on vertical face because it's a face based family. I want to change that to place on face. And then just simply click anywhere on the edge of this curb. And it will place that object and it will automatically cut right into the floor slab. And again, if we look at that in 3D you can see the final result here. And the nice thing about this technique is I can place this as many times as I need throughout my project. So if I have lots of curb cuts throughout a large parking lot area I don't have to define each one of those with a series of points and reference planes using the technique we looked at last week.
With the family, we just simply place them wherever you'd like them to go. And another nice advantage of this is if you edit the type properties of this element, you can vary any of these numbers and flex the shape of this ramp. So if I wanted it to be wider, for example. Or if I wanted to change the ramp slope that you can see in this project the slope is in rise over run. So, let me just say that it was two over 12 instead of one over 12. That will change the depth of that ramp.
So that's the other nice advantage of doing this as a family, is that everything remains flexible and you can make as many variations of this as required by your project.
NOTE: The exercise files for this course can only be opened in the most recent version of Revit (Revit 2017).
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