Buzz
We often overlook the partitions separating lanes on highways. However, these seemingly basic structures are much more advanced than they appear: Their designs have undergone extensive testing and modifications to ensure safety for drivers on both sides of the road in case of an accident. The term most commonly used for these widespread concrete barriers is Jersey barriers—but what’s the reason behind that name?
The Link to California
Before Jersey barriers, roads were separated by guardrails made of weak wooden beams, which failed to prevent cars from colliding. With the increasing number of vehicles on the roads, it became evident that a more effective solution was needed.
Concrete road barriers were first introduced in California in 1946, replacing the wooden guardrails on the dangerous Grapevine section of the state's Ridge Route highway, known for its notorious 'Dead Man's Curve.' This section had a 6 percent downgrade that frequently caused head-on collisions. The parabolic barrier placed on the median proved to be effective in reducing accidents.
In 1949, New Jersey followed suit, implementing similar concrete barriers on the Jugtown Mountain portion of U.S. Route 22 in Hunterdon County, which also featured a steep downgrade similar to the Ridge Route highway. These early barriers stood 19 inches tall and were 30 inches wide, with 2 inches buried to provide stability. Each was secured to the roadbed with steel dowels and featured a 2-inch thick white concrete outer layer to enhance visibility at night.
The Origins of the 'Jersey Barrier' Name
While the first barriers helped reduce collision severity, New Jersey highway engineers kept refining the design, gradually creating larger prototypes based on observed accident rates rather than controlled crash tests.
By 1959, a standard barrier height of 32 inches above the road surface with a 24-inch-wide base was adopted. The base was 3 inches high, followed by a 13-inch side slope before the barrier became vertical. These barriers were rolled out across several states, and though the design continued to evolve—such as the creation of a 42-inch version for trucks—the barriers retained the name of the state where they were first developed.
Jersey Barriers vs. F-Shape Barriers
Jersey barriers are engineered to redirect the force of a crash, utilizing the car’s momentum to absorb the shock and guide the vehicle parallel along the barrier to prevent it from rolling over. However, in high-speed collisions involving smaller cars, there is a higher risk of rollover, prompting the development of an alternative barrier.
According to the Federal Highway Administration, the F-Shape barrier has the same 3-inch-high base as the Jersey barrier, but the side slopes 10 inches above the pavement—3 inches less than the slope on the Jersey barrier—making it more effective in absorbing proportional impacts from smaller vehicles and reducing rollover risks.
Although the F-Shape barrier is generally preferred, Jersey barriers, along with other designs like constant slope, single slope, and vertical barriers, remain acceptable, as they pass the crash tests conducted by the National Highway Traffic Safety Administration. These barriers are also used in various other applications, such as on construction sites, around important buildings, as flood walls, or to manage erosion. There are even lightweight, portable plastic versions available.
