Jersey barrier install#
Jersey barrier drivers#

New Jersey highway engineers had found that white Portland cement was much more reflective than standard gray cement-almost two and a half times more visible at night. Its most innovative feature was its 2-inch-thick outer layer of white concrete. 22 one was formed and cast in place, on site. Unlike the Grapevine Grade barrier, the U.S. One-inch-diameter steel dowels anchored the curb to the roadbed. Only 16 of those 19 inches extended above the surface of the pavement the rest was buried to provide stability. It was, as Engineering News-Record reported, “designed to clear the mudguards and running boards of cars that sideswipe the curb and to deflect automobiles back onto the roadway without a sudden stop that might result in injury to passengers or damage to the vehicle.” State Highway Department engineers explored several different configurations before settling on a 19-inch-high, 30-inch-wide curb with concave parabolic faces on each side. When the roadway was upgraded to four lanes in 1948–49, the State Highway Department decided to try an experimental method of separating the traffic. Route 22 in rural Hunterdon County had, like the Grapevine Grade, seen many head-on accidents over the years. The curving Jugtown Mountain section of U.S. New Jersey installed its first concrete median barrier in late 1949. The barriers were successful in preventing collisions, yet 20 years passed before california highway engineers used them again. Highway officials in that state would spend the next 15 years developing the design that eventually spurred the nationwide adoption of the device. It got a write-up in Engineering News-Record, an influential and widely read publication, yet more than 20 years passed before events on the opposite coast prompted California highway engineers to return to the concrete median barrier. 99 installation was successful not only in deterring truckers from using the barriers for braking but also in preventing collisions. Carried to the installation site on flatbed trucks, they were hoisted into place and bolted to the concrete roadbed with small gaps between them to allow for drainage.

Jersey barrier drivers#

They were hollow, with internal steel reinforcement, and had iron anchors to hold them to the ground and “cat’s-eye” reflectors on both sides to help drivers navigate. Steel forms were used to give them as smooth a surface as possible. These first concrete barriers were made in precast 26-inch-high, 28-inch-wide, 10-foot-long sections weighing 3,000 pounds each, and looked a lot like the ones found on highways today.

Jersey barrier install#

So the Grapevine Grade had a much higher than average incidence of fatal head-on collisions, and in 1946 the California Division of Highways decided to install an experimental parabolic concrete median barrier there.

And they proved no match for vehicles hitting them at wide angles. But these wooden barriers were frequently damaged by truckers, who found them convenient as a supplemental means of braking, brushing up against them on downhill runs. To prevent head-on collisions, wood-beam guardrails on steel posts were installed to separate the lanes of the Grapevine. The Grapevine was a curving 6 percent mountain descent on a highway linking Los Angeles and the fertile San Joaquin Valley that daily carried an average of 6,500 vehicles, a quarter of them trucks. Route 99, it contained terrifying grades. The “Grapevine Grade” was the most hazardous portion of California’s famous Ridge Route highway, home to the original “deadman’s curve.” The highway was reconfigured in 1934 to improve the mountainous traverse, which had a more than 4,000-foot elevation change. Those humdrum concrete walls that dominate today’s highway landscape are actually highly refined pieces of safety equipment. In the 60 years since then, a huge engineering effort has gone into their development. These omnipresent wedges of concrete are universally referred to as “Jersey barriers.” But they actually made their first appearance on a treacherous stretch of California mountain highway in 1946. And just last summer they were seen being deposited into the breaches of the compromised floodwalls surrounding New Orleans. Since September 11, 2001, they’ve also helped safeguard our buildings from terrorist attacks. They line the medians and shoulders of highways in every state.