Parking Lot Grade Breaks

[kingpawn]

I'm designing a parking lot on the side of a mountain. Actually, it's not the side of a mountain but with the terrain it looks like it.

What is the design criteria to make sure an automobile does not bottom out in sags and crests?

Thanks for any feedback............

 

[CarlB]

Well you could find yourself a design vehicle (long wheelbase/low undercarriage) and calculate the grade break at which it drags. I suggest not exceeding 10% if possible.

 

[kingpawn]

Well.....at the entrance the municipality requires you to slope up from the flow line of the gutter at 5.5% and I need to slope back down at 8% to 10%. I think if I put in a 10 ft long vertical curve I will be fine.....thanks for your response

 

[saruman26]

In general, keep the net (algebraeic) difference between the two grades at around 10% or less.

 

[msquared48]

I believe AASHTO and similar highway design manuals have guidelines for what you need.

Mike McCann
MMC Engineering

 

[civilperson]

A change in grade requires vertical curve to prevent bottoming out.