Cross slope at off-street Parking Lot 2

[sdynamic]

Some municipalities have standards on the minimum cross slope for the off-street parking lot. Some have minimum 2% cross slope at the parking lot.

Is this for a drainage purpose? I think minimum 2% cross slope is relatively high for shopping center parking lots to use "shopping carts".

What would be a recommended or appropriate "Minimum Cross Slope at Parking Lot" without any drainage issue? 1% or less?

Thanks and have a wonderful day.

 

[gibfrog]

In the "poorly drained Florida coastal flat lands", 0.5% cross slope is consideed minimum. Tolerable "bird baths" are 1/4" deep. The steeper the slope, the less "bird baths". Many "big box" retailers that nationally have a 2% minimum sople allow a 1% in the "poorly drained Florida coastal flat lands". A 1% slope is usually enough to avoid "bird baths" from most qaulified paving contractors.

ADA parking code allows a maximum 2% slope (1 in 48) in any direction in a normally "flat" handicaped parking space & adjacnet van loading isle. A 2% slope is considered "flat" in most of the USA and per the ADA.

Clifford H Laubstein
FL PE 58662

 

[cvg]

I have seen numerous parking lots with slopes far in excess of 2% which helps with drainage. However if shopping carts are to be used, I would keep the slopes less than about 4 - 5%

bird baths occur because a) grading and paving operations are not accurate and low spots are created or b) ground and pavement settles causing a low spot. The low spots trap water which then saturates the pavement subgrade further weakening it and eventually causes pavement failure. In order to eliminate them you need a combination of good compaction, accurate staking, and close control on final grading and paving. But without significant slope which is commonly thought to be a minimum of 2%, the bird baths are almost unavoidable. Even in flat land Florida, steeper slopes than 1% can be designed and built with no problems.

 

[brandoncdg]

My partner is fine with doing 0.5% on concrete. Most people think this is too flat though and probably not realistically buildable in the field.

Civil Development Group, LLC
Los Angeles Civil Engineering specializing in Hillside Grading

http://www.civildevelopmentgroup.com

http://www.civildevelopmentgroup.com/blog

 

[civilman72]

To summarize the posts above - shopping centers I've worked on require a max slope of 4.5%, for shopping carts. Asphalt should be 2% minimum and concrete at 0.5% in drainage pans and 1% for sheet flow. So if you have asphalt paving, grades should be 2%-4.5%, with concrete 1%-4.5%.