Precast jersey barrier as retaining structure

[Awre]

It is proposed to use precast Jersey barrier to retain a pedestrian walkway. The walkway is leveled with the top of the barrier. The barrier will rest on a crushed stone base. The height of the barrier has to be around 36" +/-.
I found typical barrier (Type 1) at NJDOT which is 32" high:

http://www.state.nj.us/transportation/eng/CADD/v8/v8RoadwayDetails/pdf/056_CD-607-3BarrierCurb.pdf

The above detail shows the barrier is anchored to a concrete base which is not the case for my intended purpose. Rough calculations shows the 32" high barrier's weight is estimated around 450 lb/lf, and to retain same height of soil including L.L. surcharge of about 100 psf the barrier weight should be increased (about 550 lb/ lf). I think this could be achieved if the barrier's base is wider.

-Is there a standard barrier type that would provide the height/weight requirements?
- Is better to dowel the barriers together or place them loose?

Thanks

 

[BigH]

I am not familiar enough with the different variations that various agencies use - but, as a thought for consideration with respect to overturning which is what you imply, why not anchor some geogrids or "metallic strips" to the barrier and make a makeshift mechanically stabilized earth wall? The strips would likely only have to go back, conservatively for about 3 ft but would provide a wider gravity structure. Again, just a thought from a guy heading off to Bali in a few hours!

 

[fattdad]

Any chance it'll be hit by a car?

f-d

¡papá gordo ain’t no madre flaca!

 

[PEinc]

I would check what type of barrier your state normally uses or what type the contractor has in stock. Some barriers have end connections, some don't. Some have vertical precast holes for anchoring to paving, some don't. Check what is commonly available in the project area.

http://www.PeirceEngineering.com

 

[oldestguy]

When are you going to have a surcharge of 100 psf all along the thing. You might get a vehicle with "point loads" on the walkway, but the walk slab will spread that some and the earth will further spread these lateral loads along the gravity wall.

A "run of thumb" for a gravity wall is that it will be stable if the base is at least as wide and one third the height. The New jersey" barriers I have seen come close to that


What about railings? If you set them in the walkway slab, that places the "live loads" somewhat back from the wall.

Why New Jersey barrier? If cheap or free, yes. However, cheap walls can be made from reject concrete blocks at ready mix plants. They measure about 2 x 2 x 4 to 6 ft. and have more weight per ft. of height as compared to the barrier. These also look like stone on the fronts. A 4 ft. high wall easily meets the "rule of thumb". They key together along the line and have notched tops for geogrid anchoring for higher walls.

 

[Qshake]

These days, the SBC is used by civil designers quite a bit as a effective solution between the old CIP wall (small height) and a small block retaining wall. Roadway designers use these barriers, where they need to have them anyway and can make them pull double duty.

I've not seen a safety barrier wall where the retained side was subject to a surcharge. But that is more likely due to seeing them where they're open for all, on the roadway. Typically, they hold back a slope with a 3 to 1 or steeper.

Also having them used as doublt duty (barrier and retaining wall) means that the barrier is at a roadway and so the resistance is enhanced with the moment slab that is referred to above.

As to heavier bases, there are a myriad of SBC out in industry and you need only talk to the contractors to find which is best for your project. If the barrier is long enough, the contractor will want to slip form this and so your going to be dependent on the type of slip form he has. If the barier is relaively short in length, then they will use forms and the forms are split so you can actually get what ever width you need.

Regards,
Qshake

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