Portable Concrete barriers

A new type of traffic barrier brings additional safety benefits.

By Jon VanZile

It was a deceptively difficult challenge: design a temporary concrete construction barrier that protects roadside workers, doesn’t obstruct drivers’ views and can handle the impact from a vehicle moving at 45 mph.

But the state of Florida needed just such a barrier. With 56 roadway construction deaths in 2001, Florida ranked fourth in the country. Between 1997 and 2001, an average of 27 workers and motorists were killed every year in Florida, and thousands more were injured.

At least part of the problem pointed to the highway barriers that were being used on secondary roads. At 36 inches tall, the standard highway construction barrier is too big for most secondary streets because it blocks the view of oncoming headlights from side streets. Yet 9-inch concrete barriers aren’t high enough to prevent accidents, and orange plastic cones offer no protection at all.

Instead, the Florida Department of Transportation wanted something in between.

Led by Gary Consolazio, Ph.D., researchers at the University of Florida worked for three years to design a new barrier. They turned immediately to concrete, because it is relatively inexpensive yet durable and long-lasting. To hold down development costs, they relied heavily on computer simulations rather than live crash tests.

“The goal was to develop something that people could see over, something that was as short as possible but still strong enough to redirect a truck going 45 mph,” Consolazio said.
Last year, the product of their labor was unveiled. Engineers had designed an 18-inch, portable concrete barrier that can withstand an impact from a 4,400-pound pickup traveling at 45 mph, yet is flexible enough that a compact car could hit it at 45 mph without injuring the vehicle’s occupants .

Besides the promising crash characteristics, the new barrier has some powerful design advantages. First, the 12-foot-long sections of barrier can be connected end-to-end. This means the barrier is flexible– it can go around corners or wind down a bending road.

Second, the whole is stronger than its individual parts. Crash tests showed that when a vehicle hits the barrier, the force of impact is absorbed down the length of the barrier, rather than localized at the point of impact.

Finally, the connected pieces are heavy enough that they don’t need to be anchored to the roadway. They are simply set in position and connected, and they can easily be moved after the job is done.

“A key aspect of the system is that it doesn’t require anchorage,” Consolazio said. “It redirects vehicles through internal resistance.”

Although the barrier meets both the Florida DOT’s and the Federal Highway Administration’s safety standards, it has not actually gone into use. Currently, the University of Florida has licensed only two precast concrete manufacturers.
Seminole Precast of De Bary, Fla., one of the licensees, helped cast the original two lots for crash tests. According to CEO Martin Neiswander, the barrier is relatively complicated to fabricate.

Not only is it reinforced through the center with steel, both ends are fitted with stainless steel connector pieces. Also, the barrier must meet stringent state and federal safety specifications.

“It’s more complex than other safety barriers because of the connecting system,” Neiswander says. “Each piece also must have a stainless steel plate on top with all the data required by the state and the University of Florida, including the patent number.”

Ultimately, no one knows exactly how large the market will be for the temporary barrier, or what kind of opportunities exist for precast companies.

In Florida, the Department of Transportation requires roughly 100,000 feet of temporary barrier every year, according to Karl R. Zawoy, assistant director of the Office of Licensing Technology at the University of Florida. The University offers a standard, nonexclusive contract to make the barrier.

Because of its potential, the University of Florida is hoping to meet a much larger market than just one state. Thus, the national “market is wide open,” according to Zawoy, who roughly guesses a national demand of several million feet every year.

For more information on this product, contact Karl R. Zawoy at the University of Florida, (352) 392-8929 or kzawoy@ufl.edu.