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Cross slope at off-street Parking Lot
2

Cross slope at off-street Parking Lot

Cross slope at off-street Parking Lot

(OP)
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.

RE: Cross slope at off-street Parking Lot

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

RE: Cross slope at off-street Parking Lot

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.

RE: Cross slope at off-street Parking Lot

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%.

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