Cattle grid
The modern cattle grid for roads used by automobiles is said to have been independently invented a number of times on the Great Plains of the United States around 1905–1915.
Cattle grids are common worldwide and are widespread in places such as Australia, the Scottish Highlands, or the National Parks of England and Wales.
[6] Cattle grids, as they are called in Great Britain, Ireland, and South Africa, are known by a wide variety of other names in other parts of the world.
Mata burro ('donkey killer') is the preferred name in Brazil and Venezuela, while guarda ganado ('cattle keeper') is what they are called in Argentina.
Placed in or on the ground and filled, a finished cattle grid with 4,000-pound-per-square-inch (28 MPa) concrete reinforced with 5⁄8-inch (16 mm) fiberglass (GFRP) rebar can support vehicle loads of up to 32,000 pounds (15 t) per axle.
The light-dark pattern of lines on pavement resembles a true cattle grid to animals, and by association think they will not be able to cross.
Experts say that "a cow's depth perception is such that it makes little or no distinction between painted stripes on a dark background and bars over a pit.
A station owner in Queensland, Australia, told a reporter that after some of his old bulls leaped a painted grid, the younger ones lost their fear of walking across.
[18] Drawbacks include the necessity of spraying vegetation with herbicides to keep weeds from shorting out the grid if there is no barrier between the wires and the ground.
One that was patented in Illinois in 1955 and another invented in New Zealand in 1979 are similar; each resemble "something like the framework of an old-fashioned metal bed" connected to a battery or high-powered fence charger.
[19] Another type was patented in two versions by an Oregon inventor in 1956–57; it consisted of 20 current-carrying synthetic rubber strips mounted on a wooden frame.
The invention proved highly effective in deterring all animals, including dogs, and it was maintenance free, easy to drive over, and safe.
[19] A fourth type, homemade, consists of two sections of woven wire or steel plate laid on a concrete slab and set apart from one another on either side of a fenceline.
[29][30] In areas with heavy snowfall and long periods without a thaw, snow can accumulate beneath a grid and allow animals to walk across.
Horses are particularly vulnerable to cattle grid injuries, as their single-toed hooves can slip between the bars and trap their legs in an easily broken position.
[26] However, a Texas Highway Department official reported that adding three 20-inch (51 cm) painted stripes—arranged yellow, white, yellow—on the road in front of a cattle grid deterred goats from approaching or crossing the guard.
