Scientists at Norway's Foundation for Scientific and Industrial Research (SINTEF) are proposing to place aluminum panels in guardrails to act as noise barriers.

“Aluminium is corrosion-resistant, the material is widely used in energy-absorbing systems in many applications and it can easily be worked and recycled," says SINTEF scientist Dirk Nolte. "It has a good ability to reflect sound, and transporting it is also energy efficient because it is light in weight.”

SINTEF scientists Dirk Nolte and Nguyen Hieu Hoang investigated how aluminium noise-barriers could be directly mounted on guardrails. Photo: SINTEF/Thor Nielsen.According to SINTEF, noise barriers must weigh at least 20 kg per square meter to provide adequate noise damping. If aluminum is used, SINTEF says that requirement is met by using a single eight-millimeter-thick panel.

In searching for an appropriate design, Nolte’s colleague Nguyen Hieu Hoang used computer modeling to simulate what happens when vehicles collide with a so-called "yielding" guardrail—that is, one designed to absorb forces from collisions to reduce injuries—that also is fitted with a noise-barrier.

The results suggest that panels matching existing guardrail height—no more than 75 cm high—are desirable to lower traffic noise while maintaining the guardrail’s ability to absorb the force of a vehicle impact.

Magnhild Finnanger, senior engineer with the Norwegian Public Roads Administration, sats that yielding guardrails are typically sited where the terrain falls away from the road. "On such stretches of road, many houses therefore lie below the level of the source of noise," she says. "Such houses can obtain effective noise protection even from low noise barriers that are located at road level.”

SINTEF is now looking for a manufacturer to produce the noise barriers for trial installations on stretches of road in Norway. According to Finnanger, Norway's Public Roads Administration intends to begin testing designs validated through SINTEF’s computer model.