Creating a Curved Ramp

Hello guys!
I have this quite complex “building” here. In the middle, where the gap is, i want to build a ramp that starts from the bottom in the front of the building, to the top in the back of the building…

My approach was to take the edges from that gap, and drape them as a line onto a inclined, flat surface. I then used the follow me tool to extrude a rectangle along this line to make the ramp.
At first, it looked ok. However, the surface of the ramp is not horizontal… it gets all distorted… i guess its because the path is not straight and has alot of curves in it… but it should be possible to have a curved ramp whose surface is horizontal? I just cant figure it out!
Here are the rest of the pictures for a better understanding :slight_smile:

Any help would be greatly appreciated!
Thank you very much!


I would ‘PushPull’ a grouped path to full height, and use a ‘ramped’ surface to intersect it and remove the top geometry…

can you post the skp?


oh of course… it’s so much easier and faster this way… however, i think this leads to the same result essentially…
sure, here you go ramp.skp (317.0 KB)

thanks so much for your reply!

You have a number of issues to consider…
First I assume this building has several stories.
I also assume that this ramp is intended to allow people to access these stories.
If so, then it needs flat landings [length>=width] at each entrance location.
It also needs intermediate landings - most building codes will limit a ramp to rise no more than ~2m before a flat landing [length>=width].
Also building codes will restrict the ramp’s slope to say 1:20 - so that sets so limits too.

I think you ought to do the ramp/landings in individual pieces - one piece per rise or story.
Make it a group or component, make it wider that the gap it’s fitting in, then intersect it with the model and remove the unwanted parts…

The are plugins which do a followme without the twist - but there’s much to consider before getting there…
e.g. Extension | SketchUp Extension Warehouse

your path and building should possibly need to match up first…

they are quite different from each other…

take a section slice from the buildings and overlay it on you path outline…


thank you so much for your step by step solution! it works great for curves like that, but in my model, you see, the curve at the end is almost 90 degrees… so the pitch of the simple, straight ramp I made in the beginning, actually becomes a pitch in the ramp itself (this “twisting”) omg so complicated…

and yes you are completely right, i will have to make landings for the entrances :slight_smile:

but i think that little plugin you suggested is exactly what i was looking for! incredible… thank you! im in heaven… :smiley:


Couldn’t you draw the curved shape from a top view, then extrude it up too far and make it a (solid) group. Then draw a large rectangle and make it a group. Place the rectangular plane into the Extruded Curved Surface at the level and angle of the ramp you want. Assuming both groups were solids (volume measurements showing in Entity pane) then go to the Solid Tools. Trying to follow the " this cuts that out but leaves only the remaining…" explanations isn’t recommended. Use the 2nd from the right called “Trim”.

First select the inclined plane group. Then click on the icon “Trim” . The cursor will now have a tiny ‘2’ attached and the message at the bottom will read; “Select the 2nd solid” or something like that. Now click on the Extruded Curved Surface.

Don’t move a muscle! You now have the inclined plane still selected, but the Extruded Curved Surface looks the same but has actually been neatly cut in two pieces, above and below the plane. Careful what and how you select things, and you can “have your way” with what’s now appearing. If it was me, I’d next select the top half of the Extruded Curved Surface completely, left to right. Make this a group and you’ll have captured everything into what is now 3 groups.

As a carpenter/framer/house builder we encountered a similar problem back before personal computers, (but after color tv).

To craft the hand rail out of a steel rod, for a spiral stair case with a diameter of 5’, we wanted to roll a length of 5/8" round steel rod into a circle to establish the handle’s circular shape. Then we could pull up one end to match the height of the spiral stair case, but of course the diameter of the circle would shrink, a lot.

After a long weekend end of ‘special oracle’ consultation someone figured out that it was a comparison in right angled triangles; The height of the stairs and diameter of 5’ were the altitude and base of one right triangle; The height of the stairs and the circumference of the spiral were the altitude and base of the 2nd right triangle. The hypotenuse of the 2nd triangle was the railing length and our new circle’s circumference.

I think what ‘Chris’ is describing at the end of his ramp, is a constantly increasing ratio of what is described above, or has introduced yet another dimension of each upward iteration being also smaller in shape. Wow, NASA stuff.
I’ll bet that water going down a drain is the algebra he’s looking for.

Nice approach.
From a practical viewpoint and assuming these types of structures will be built of concrete, I’m curious about connection detail, as in how does a horizontal piece ‘sit’ onto a vertical piece supporting it? Edges of concrete can’t be built out to the fineness that we draw and that ‘cut-off’ point is relative to the weight of things. I’ve decided not to draw any concrete counters with ‘under-mount’ sinks, because the sinks are only practical with slimmer materials like Granite, for an example. If this ramp is well supported underneath the connection would be much different than if it were more of a bridge.

I’ve noticed some people drawing windows, draw the corners as components or groups first and then fill in sides as needed. Part of the reason they do that is to avoid re-drawing connection details I think. It makes them almost too troublesome to edit as a caveat.