Ramp Dimensions ?

[eyepea]

Any ideas on the maximum gradient I can have for a ramp for vehicles pls ?

Let me explain the situation:

Am making an additional vehicle entrance to the house. The ground is about 2 feet higher than the road. So either I have to lower the ground level in the area where the vehicle will come in, let me call it, parking area, or make ramp to, or do both.

I need to allow most kinds of vehicles to use the ramp without hitting the underside and both front in and reverse should be possible. Well vehicles with higher ground clearance will have no issues, but need to allow for cars with low ground clearance and low front buffers too.

If I need to lower the parking area, it should be a minimum due to various reasons (like pipes running under, which I will have to lower or re-route - a bit of a bother).

This means the height of the ramp has to be the maximum possible.

The length of the ramp has to be the minimum possible as I want the parking area to be flat, and I cannot extend the ramp into the road.

Hope you got an idea of my requirement.

I search around and got the recommended dimensions for the gradient for ramps to be about 1:10 for heights up to 1.5m. (for higher level differences it was 1:12 ugh).

But this was for parking lots.

The length of the parking area is about 15 feet.

The length I would like to have for the ramp is about max 3 feet, 2 feet better. That is allowing for the gate pillars and also having the ramp over the drain that runs along the side of the road.

If I have a gradient of 1:10, almost entire parking area would be a ramp. Not OK.

A gradient of 1:10 looks quite shallow. I have seen entrances of houses with very steep ramps. But then perhaps only jeeps with high ground clearance might be going on them. A car might hit the underside while starting on the ramp or going over. (don't want to try and find out ).

Some of you may wonder, if the recommendations in the web say 1:10, why ask.

Well 1:10 or 1:12 as I said is for parking lots which might accommodate all possible vehicles including perhaps who knows - motorized wheel chairs and also to meet various standards and speed of travel etc and all of it may not be applicable to a local situation.

Also if the level difference is low, the gradient could perhaps be steeper.

For example, there is no ramp or gradient for a 4 - 6 inch high pavement and most vehicles will not have a problem going over it (if you don't mind the bump ).

I could compromise and have a max gradient for the ramp with say a max ramp length of 3 feet (or preferably 2 feet), and to fit that max ramp height allowed, lower the parking area the minimum possible value.

What kind of max gradient can you guys recommend for this situation ?

Any links to a previous topic covering this (could not locate) or any other site with the required info, pls let me know.

Thanks

[Davy]

Interesting question. First of all, I’m happy to see that you have done your homework before posting on the forum.

Reading through your requirements, you don’t seem to be having many options. If the garage floor is 2feet above the road level and if you can only extend a ramp that is 2feet in length (along the ground), you’re going to form an angle of 45 degrees which is too steep for most cars.

I did some Googling myself just a while ago and it looks like the recommended angle is 15 – 20 degrees max. After some calculations, the length of the ramp (along the ground) would have to be ranging from about 5.5 feet to 7.4 feet for 20 and 15 degrees respectively.

If we assume that you’re going to go for a 20 degree angle, we’re looking at 5.5 feet along the ground from the road to your wall, which is way over your restrictions. So, have you thought about having one part of the garage floor sloped down (the part towards the wall) while the rest is flat? Since only a small part is sloped down, it’s very unlikely that either the front or the rear wheels (of the vehicle being parked) will be sitting on the slope.

If you’re going for the above method, you might have to go for a sliding gate or a roller door.

Just my 2 cents. Hope this helps. Good luck!

[Rumesh88]

In fact in building a ramp for vehicle entrance, the slope is only one of the several parameters. In this particular situation I'm afraid the limitations are really restricting any prospects of a practical solution unless you compromise on certain things. However, what you need to consider is as the vehicle with the lowest clearance to wheelbase ratio come out of the ramp the undercarriage should not touch the knee of the ramp. You can have curved knee or better still design a curved ramp for that matter!. This however is difficult to construct and would not be aesthetically very appealing. The other alternative is to design the ramp in let's say four steps of 4 inch height assuming you don't mind the bump (even with curved or sloped knees. Mind you it is not a very pleasant experience when you pass your car everyday over a four inch high step!). The width of two steps added together should be greater than the longest wheelbase you have in mind. This ensures that your rear wheel passes the first knee before the front wheel gets on to the third knee.

See if this solution works for you.

[eyepea]

Thanks for the info and the ideas.

Yes quite a few points to consider!

Many thanks!

[SeanD]

International standard minimum for (non-motorized) wheelchair ramps is 1:12. Then again, I don't think that's really followed in Sri Lanka as I've seen plenty of buildings that have a ramp that's hard to climb even on foot, just "for the sake of it." 1:12 is probably OK for any vehicle.