Reverse Crown 1

[cr1973]

I want to use a reverse crown profile to drain water from a city owned driving and parking area. This area will be reconstructed and is small enough so that we don't need onsite drainage.

Is it ok to have 2 8ft panels, with a 2% and -2% slope each towards the middle? Will having a joint right at the flow line be a problem?

As you can tell, concrete design is not my strong point!

Any pointers will be appreciated! thanks!

 

[jheidt2543]

If you are in an area that has freezing tempertures during the winter, it may not be a good idea. What happens if the water freezes in the middle of the drive/parking area? You could have cars with one wheel on ice or people walking across ice in the middle of the drive/parking area. Just a thought.

 

[Maury]

I have seen this done in areas with low-volume, low-speed traffic and there didn't seem to be a problem. As jheidt said, drainage is important. What longitudinal slope will you have? If it's minimum grade, it may cause ponding. a slotted drain pipe down the middle could be useful.

 

[cr1973]

Well this reverse crown drive basically just leads to a water booster station and stand pipe. The only traffic will be the occassional utility or maintenance vehicle. This drive will lead to a large concrete staging area, about 40x50. The way the land lays, this staging area will drain back into a grassy area, and the access drive would drain inthe opposite direction, to the street, via reverse crown.

I am looking at a good .5 to 1% slope, longitudinally.

 

[GeoPaveTraffic]

In addition to the other comments I would add, don't put a joint at the lowest point in the pavement. This will tend to encourage water to get below the pavement and will likely lead to problems in the future. I would recommend placing a 2 to 3 foot wide gutter section in the center, with the 2% side slope, but no joint in the middle. Then you can construct your pavement section on either side.

 

[cr1973]

Good idea, I had thought of that aswell, but was unsure how well a 3' wide strip of concrete would hold up. Considering this is an extremely low traffic area, and most of the vehicle weight would be on the adjoining slabs, this strip of concrete would probably hold up fairly well.

 

[johnhan76]

Here in my area (flat) the minimum long. grade is .7%

 

[johnhan76]

Make sure you space your grates correctly or you will have a lot of flooding.

 

[cr1973]

Well I wasn't really planning on having any grates, I was jus going to channel the flow into the curb and gutter in the street.

 

[porchtec]

Peers and Seers, ...
I have the following questions:
#1. The width and thickness of the section used to pave the inverted crown invert?
#2. The number and size of the rebars that did the job in light traffic conditions?
#3. Unintended consequences and things that went wrong?
Thanks,
...porchtec <cspdjp@juno.com>

 

[dicksewerrat]

Write or call the City of Mpls. for their Alley pavement design and cross section. they have been using the same design for 50+ years with few problems. I think the Street Dept. Number is 612-673- 5600. But you may be able to go to their website.

http://www.ci.minneapolis.mn.us

 

[cvg]

recommend 8 inch thick Class A concrete, no rebar needed, expansion joints at maximum of 50 feet spacing.

 

[porchtec]

Thanks dicksewerrat and cvg. Both responses are appreciated. I'll be back with progress on this project.
...porchtec