They’re certainly a common sight on the road, but not many people give any more attention to road partitions apart from trying to avoid them. Concrete partitions are used on U.S. highways to divide the traffic. These partitions have a distinct look to them, but if someone were to use one word to describe how these partitions are, they’d probably say solid. However, there are more to these concrete partitions than what meets the eye. These road dividers are actually quite the work of true sophisticated engineering. They have been designed to promote safety on roads where cars and trucks typically go at least 55 mph up to 70 mph or more. While many might refer to these concrete slabs as simply dividers or partitions, they actually have a proper name. These road partitions are officially called Jersey Barriers, and you could probably imagine why. The story of how the Jersey Barriers came to be is something that not many people might be aware of, but it’s an interesting piece of history that still lives on to today.
Before 1946, standard wood beam guardrails divided highways. While cars were relatively slower then and speed limits a lot lower as well, it’s still very easy to surmise that wooden beams to divide highways were quite dangerous. First of all, that did not prevent cars from driving on to oncoming traffic. California was actually the first state that devised a better road partition that was made out of concrete. Concrete’s obviously a lot stronger than wood, so it only made sense to put it up as replacements for the old guardrails. There’s a section in the California Ridge Route highway that houses the original “Dead Man’s Curve.” This section is called as such due to the fact that the road has caused quite an alarming number of head-on collisions. The 6% downgrade is the culprit, and it seems that concrete road barriers were the solution. California did the switch in 1946, and just 3 years later in 1949, the state of New Jersey came up with their own version of concrete slab partitions, which ended up being the better versions in the end.
The original Jersey Barriers measured 30 inches wide and 19 inches high. Anchored by steel dowels, there were 2 inches of it buried in the road to give the barrier even more stability than what the concrete itself offers. There was also a 2-inch thick outer layer of concrete that’s usually painted white for more visibility especially during nighttime. These original Jersey Barriers were already quite successful in deterring some collisions, but the New Jersey state highway authority and their engineers didn’t stop there. They continued to work on the designs, changing the size, shape of the barrier to see what would work the best. By 1959, the engineers thought that they had found the best combination out of them all: a standard barrier that measured 24 in wide in the base and 32 in high. The base of this barrier measures 3 in tall and there’s also a 13 in slope on the side before it becomes it shoots up vertically. These were the barriers that would eventually carry the name of the state as it becomes implemented in other states over the course of the next many years.
The Jersey barriers were not just designed to separate traffic on the road. With this last design, these barriers redirect the impact of a crash by sliding a crashed vehicle along the side of the barriers using its momentum to propel itself. This prevents a hefty rollover that can cause even more damage in the end. However, it turned out that the Jersey barriers weren’t enough to prevent rollovers in high-speed crashes, so the New Jersey highway authorities decided to create another barrier specifically for this: the F-barrier. The difference between the Jersey barrier and the F-barrier is in the size of the sloped side. Instead of measuring 13 in as it does on the Jersey barrier, the F-barrier’s sloped side goes up 10 in high—a total of 3 inches shorter to better absorb impacts from smaller chassis. This seemed to prevent rollovers much better than the Jersey barriers, so the F-barrier actually became the more preferred barrier eventually. Still, we see Jersey barriers around because it’s still an acceptable barrier nationwide as confirmed by national highway authorities.