UF Engineers Develop A Safer Barrier For Road Construction Zones

June 25, 2003

GAINESVILLE, Fla. — The culprit in more than 1,000 fatalities and 40,000 injuries annually nationwide, construction zones are notoriously dangerous places for road workers and motorists.

But help may be on the way. Using a combination of computer simulations and traditional crash tests, a team of University of Florida civil engineers has designed and successfully tested a new barrier for secondary roads that prevents errant vehicles from entering construction zones while minimizing danger to motorists.

The Florida Department of Transportation, or DOT, expects to begin using the barrier on urban and suburban roads with maximum speeds of 45 mph as early as next year. The barrier also could be adopted by other states, according to DOT officials.

“As the crash tests on this new device have shown, we believe this device will be an effective and safe way to shield motorists from hazardous objects and drop-offs and work zones,” said Jim Mills, an engineer with the Florida DOT’s Roadway Design Office.

With 56 deaths in 2001, Florida ranked fourth in the nation in roadway construction fatalities behind Texas, California and Georgia, according to the National Work Zone Safety Information Clearinghouse at the College Station-based Texas Transportation Institute. Between 1997 and 2001, an average of 27 motorists and workers died and 2,475 were injured in work-zone crashes annually in Florida, according to DOT statistics. Road worker injuries and deaths have become such an issue nationally that many states, including Florida, double the fines for speeding in construction zones, while others add points to driving records for speeding in construction zones.

The DOT does not track how many accidents happen in work zones on highways versus those on secondary roads, Mills said. However federal rules now being phased in seek to increase the safety of all road barriers.

The rules prompted the Florida DOT to seek an alternative to its traditional work-zone barrier for slower-speed roads, which consisted of 9-inch-high curbs. The agency hired UF civil engineering researchers Ralph Ellis, Kurt Gurley and Gary Consolazio to come up with the new design.

The goal: Devise a barrier that could prevent a 4,400-pound pickup approaching from an angle of 25 degrees or less from crashing into the work zone. The rules specify the pickup because it is as heavy or heavier than most cars and SUVs, while 25 degrees is the maximum angle at which a vehicle can reasonably be expected to encounter the barriers, which are typically placed along roadsides. The new barrier also had to be relatively safe for those in the colliding truck or car – and break down into 12-foot segments that were inexpensive, and easy to install and move around.

Using a UF civil and coastal engineering supercomputer and computer simulation software, the engineers conceived, designed and tested four new designs without ever building a single physical version. The supercomputer contains 20 high performance processors that work together simultaneously, performing tasks in hours that would require months to solve if only personal computers were used.

The result: Moving digital images of simulated crashes that allowed the engineers to estimate what would happen in collisions. The simulations not only produced data on impact-related stresses in the barriers helpful in the design work, they also saved the cost of multiple real-life crash tests, which run $20,000 each.

“We did all of the concept development using simulation,” Consolazio said. “Even the size of the bolts connecting each segment of the barrier was tested based on computer simulation – whether a 1-inch or 1 1/2-inch bolt worked best.”

A simulation of one design showed the pickup truck “snagged” shortly after the collision, bringing it to such a rapid stop that the accident likely would cause serious injury to any occupants. The engineers rejected that design and three others, finally settling on a version shaped like an upside-down pyramid with the tip cut off. Each segment of the barrier is connected to the next with a bolt, but none are connected to the roadway. When a truck hits the barrier, the force of the impact disburses down the barriers.

“When one segment is hit, essentially all the barriers down the line absorb the impact, so they all work in unison,” Gurley said.

The research team ordered 15 of the barrier segments built and hired a California company that specializes in vehicle impact testing to pit them against a real-life collision with a pickup. The result mirrored those of the computer simulation. In a video replay, the pickup approaches and slams into the barrier then barrels along its perimeter, without either flipping over, stopping too fast or jumping the barrier and entering the construction zone.

Mills said it is possible other states will begin using the UF-designed barrier as well.

“We definitely have an interest in doing what we can to make our roads safer as well as our work zones,” he said.