Maximum Vehicle Ramp Slope



I'm currently working on a parking structure and can't seem to find a definitive maximum vehicle ramp slope. Some places says 16% and even 20%, but I haven't found a specific Code that states this.

The space I have to work with is limited so the ramp slope has become crucial to the project at this point. Id love to hear about any experiences that any of you have had on any parking structure project with this situation.


Apr 22, 09 2:25 pm

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From 2006 IBC:

406.2.5 Ramps. Vehicle ramps shall not be considered as required exits unless pedestrian facilities are provided. Vehicle ramps that are utilized for vertical circulation as well as for parking shall not exceed a slope of 1:15 (6.67 percent).

so that's if you're parking on the ramp .. are you designing basically flat parking with a circular ramp at the end? or split level parking?

Apr 22, 09 5:03 pm


I'm designing flat parking levels with an express ramp for vertical circulation only.

Apr 22, 09 5:06 pm

Really depends on your local parking code.
check out this webpage of my city's design guidelines. Here we can go up to 15% but you need at least 20' at start and end at a shallower slope to avoid bottoming out the vehicle. As car geometry is the same globally I'd say this rule applies everywhere.

IF this still doesn't meet your objectives the only other solution is the dreaded Car elevator!

Apr 23, 09 2:07 am

seattle is sim to vancouver, w/ transition zones at either end of the max slope area.

Apr 23, 09 2:18 am

I have done 22% before, but it was a very unique circumstance. We needed to get from the street level to the third level parking in one shot. It is possible, it makes the city nervous, and i think it is a bit hazardous as you have very limited visibility of the top of the ramp until you are almost on top of it. As people tend to build up speed to get up it, I would recommend a shallower slope if asked to do it again unless there were no alternatives (such as this case). If the project does require something that steep another suggestion would be valet parking only. Every time i think of gramma and her Lincoln trying to drive up that ramp i cringe.

Apr 23, 09 12:39 pm

To clarify.. the city i was in at the time did not have a maximum slope for parking ramps.

Apr 23, 09 12:41 pm


Right now I have a 20% straight run with two transitions slopes of 12% at each end.

The structure is to accommodate employees for a Police headquarters, so hopefully no gramma but plenty of Crown Victorias.

Apr 23, 09 12:43 pm

you'll want to either make the aprons 10% or split them into 2 pieces.. for a double apron.. 10' at 7% then 10' at 14% for a 20% ramp and the reverse at the top. 8% is close to the maximum i would recommend for an apron unless you can verify you have adequate ground clearance for all vehicles you will accommodate. Not being a public garage will be a benefit. Good luck

Apr 23, 09 4:45 pm


Apr 23, 09 4:48 pm

I was amazed when I first entered a parking structure in Rio....they
have a crazy light system which lets the traffic move in one direction up or down. You have to wait for the green light.....then you go like hell. The ramp is just wide enough to accomodate an automobile.

Then again if you want your car washed the parking attendant is more than happy to have one of his buddies wash and wax your car while it is in the garage.

Happy ramping...

Apr 23, 09 7:39 pm
Jamil Khalid

the Maximum slope for covered ramp is 20% and for open ramp is 12% if you have limited space and it is open you can cover it with 20% slope or you can take a single story garage lift (elevator ) it is not too expensive nowadays.

Apr 24, 14 5:37 pm


i m currently doing a prjct multi level parking in which we give a basement,stilt,upper deck parking ... should anyone have a parking design standard.... and also a slope parking standard...........

plz give me ..........

Apr 5, 16 2:16 pm
Non Sequitur

^ do your own damn homework.

Lazy students.

Apr 5, 16 2:39 pm

The key is the 10-20' depending on the local code that has to be half the slope before reaching the top and bottom. 

Draw a section before you start in on the plans as this governs everything.  Also look into ways to reduce the structural depth and factor in the beams under the slabs in the design.  This can trip up your design if you are not carefull

Over and OUT

Peter N

Apr 5, 16 11:16 pm
Featured Comment

Max ramp slope, transitions at top and bottom, and parking space slopes are most likely regulated by the local zoning code, in the chapter covering parking.

If there are no rules about it in the jurisdiction, the practical max is 20% for most types of vehicles... and you'll want the two-stage transitions mentioned above by Gabriel if you're that steep.

That said, also look at the jurisdiction's (street) engineering standards... which will probably be posted on their website.  Those will tell you a lot about the jurisdiction's attitude regarding vehicular access facilities.

Lastly, be mindful of accessibility issues... If a sidewalk crosses your ramp, it can't have a cross slope exceeding 2%.

Good Luck.

Apr 20, 16 12:04 am

Guys what do you mean by 20% ?is it equals to the degree of angle?

Nov 25, 16 2:04 am
Non Sequitur
^ you're not very good at math.
Nov 25, 16 6:17 am

Clifford, it is rise over run expressed as a percent. You did it inabout 8th grade math class.

Nov 25, 16 8:47 am
anand hirawat

what if , we design a ramp for the bus movement?

Apr 22, 17 11:26 am

My area of practice is automotive facilities, specifically luxury car dealerships.  Often these have structured parking, and we have to carefully consider the ramps.  The question of code maximum percentages was correct as the IBC limited park-on ramps to 1:15 (6.67 %).  Express ramps in private parking garages are not regulated by any code I've seen and we've done them as steep as 20%.  15% is a better if you have the room.

As for transition, this is vital and you MUST understand the types of vehicles that will be driving on the ramp.   Low exotics are the most difficult to accommodate, and the design requires radius-ed transitions (not the 50% of the ramp slope as often quoted).  For the Porsche GT the radi are 150'-0" at the bottom of the ramp, 75' at the top.

May 27, 17 1:21 pm

Hi, I'm currently working the carport for a residential house. The finish floor level of the carport is 400mm higher than the road and I am having a doubt of the slopes, the slopes are; 1% from the wall of the house running to a length of 6m, and from the end point another 11% that runs to a length of 1.8m and lastly an 8% from the end point of the 1.8m length connecting to the road. Is the profile would be okay? Anyone? Thank you.

Jun 23, 17 4:24 am

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