Cattle guards are available in many different styles and designs and the proper load-carrying capacity is critical for an effective crossing. Too much capacity is not economical while not enough can be catastrophic.
Cattle Guard Ratings
The American Association of State Highway and Transportation Officials (AASHTO) establishes the required cattle crossing requirements for use in public roadways. Below is a brief chart of load ratings:
There are many different calculations that go into establishing each required rating. The distance between axles of the vehicle play an important role in the stress that is imparted on the support structure below. This is further complicated by the passing of two heavy vehicles on the same guard.
For a glimpse into how complicated they can be, see the pdf calculations used by the State of Minnesota by clicking here! The numerous factors that are involved in a safe crossing have lead to a national load rating that simplifies the public roadway requirements for contractors.
Public Use Cattle Guard Ratings
The minimum requirement for most public roadways is the HS-20, 16 ton per axle capacity. The AASHTO provides guidelines for structural designs for use within highway boundaries. It was created in 1914 to provide guidelines for the design of structures within highway boundaries.
The highway rated guards are available in both round top rail and flat configurations.
The term flat, refers only to the very top of the rail and is designed to provide a smoother crossing for higher speed traffic. Below, you can see the picture of the rails used.
This guard creates large gaps that create a physical barrier to flat-hoofed cattle. The distance between the rails won’t allow livestock to balance their hooves enough to put weight on their leg. This prevents them from even trying to cross.
They are an effective design and provide a more comfortable ride for cars and trucks while crossing.
The HS20-rated round rail guards are more economical than the flat. They’re very popular around the country and are typically used in slower traffic areas.
The design features not only the spacing between the rails as a deterrent, but the round top rail is a deterrent on it’s own. The rounded surface won’t allow a flat hoof to easily balance on it. This creates extremely uncomfortable and treacherous footing hoofed animals and they won’t put any weight on their hoofs due to the instability.
Cattle Guard Sizes
Barn World offers a large selection of both round and flat top rail options. Most are available in a 6′ or 8′ distance in the direction of travel. The guards can be bolted side-by-side or end-to-end for extra length or widths. They are designed for public highway use and confirm to the AASHTO load rating requirements
If we can help plan your project or forward a quote for your review, please let us know and we’ll be happy to help!
Barn World – www.BarnWorld.com (720) 238-2190