#### jg91

##### Member
Hello All,

Long time reader of control booth but this is my first post. I am attempting to build a curved ramp for an upcoming production and need to calculate the angle that the ramp is on.

First and foremost, I want to make sure the ramp will be safe and walkable, but also need to make sure it will fit in the space. The upper platform that the ramp is going to is 6' tall and the ramp will be starting at ground level. My earlier calculations were that I need a 24' ramp, but my thought is that if the ramp is curved i get a long distance than a straight ramp. This may not be true but thats why I am here to find out.

Any ideas on how to calculate the angle of a curved ramp would be most help. Also if you have any other comments feel free to post them!

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#### BSchend

##### Member
A curved ramp at the same angle will only save you distance if the curve completes a full circle. Otherwise the ramp is the same surface area. You say your curved ramp is shorter, but I'm guessing that's by sacrificing the angle on the inside of the curve. Imagine if you laid a flooring on a spiral staircase. The outside edge would be flatter and the inside edge would be steeper, since more elevation is gained over a shorter distance.

#### jg91

##### Member
A curved ramp at the same angle will only save you distance if the curve completes a full circle. Otherwise the ramp is the same surface area. You say your curved ramp is shorter, but I'm guessing that's by sacrificing the angle on the inside of the curve. Imagine if you laid a flooring on a spiral staircase. The outside edge would be flatter and the inside edge would be steeper, since more elevation is gained over a shorter distance.

Thanks for the reply!! That being said, do you happen to know what size ramp I would need to have a walkable surface in order to get to a 6' platform?

#### BSchend

##### Member
Your 24' length is probably the shortest you could go. Anything shorter and the angle would be pretty severe.

#### bobgaggle

##### Well-Known Member
Not sure how it applies to you, but slope has been discussed here: http://www.controlbooth.com/threads/ramp-length-requirements.20294/

Also pay attention to the radius of the curve and the width of the ramp. If you're turning a tight radius you're going to render the inside of the ramp virtually unusable because it'll be too steep to walk on. Make sure it's wide enough to walk on safely/comfortably...

#### BillConnerFASTC

##### Well-Known Member
What am I missing? 6' in 24' is 1:4 - not acceptable in my opinion. You need good reason to ramp steeper than 1:8 - so 48' of run to get up 6'. Curved complicates construction but doesn't change the rise to run and if you base it on the center line, I don't believe it being steeper on the inside of the curve will be significant.

#### kicknargel

##### Well-Known Member
Note, too that curved ramps are pretty hard to build. The plywood has to actually be twisted - it's not in one plane. Can you have a series of ramps and landings? Or ramps and steps, to help lessen the amount of rise you need to get out of the ramp?

What type of production is this? Student / pro / community?

#### bobgaggle

##### Well-Known Member
Note, too that curved ramps are pretty hard to build. The plywood has to actually be twisted - it's not in one plane.

You can fake most of it, given the long 48'+ Run. You can facet it, which is a lot of math and layout skills. or you can built most of it in one plane, then at the top where it meets your platform, to the decking out of 1/8" luan (like 4-6 laminated layers with lots of framing) and twist that into flush with the platform. If you go that route I'd place the planar piece of the ramp and platform where they need to be, leaving a gap where you're going to use the 1/8". Put a ledger on the platform and end of the ramp, then start twisting/fitting the luan into place. Once you get one sheet glued/stapled in how you want it, build framing under it to fit. After that, contact adhesive or a glue wash on the top of the luan and start your laminations. If you laminate and frame properly it'll be incredibly stiff and stand up to a lot of abuse