Wood-Concrete Hybrid Sound Abatement Walls

British Columbia communities looking for ways to reduce their environmental impact are finding that wood is a less expensive, lightweight, sustainable and attractive option for reflective or absorptive sound walls along highways to reduce traffic noise. In the Lower Mainland, four recent projects were completed, which incorporated roughly 1,300 lineal metres of a woodconcrete hybrid to construct sound abatement barriers. These projects included a perimeter road for the new Port Mann Bridge and a demonstration project at McCallum Road in Abbotsford. The wood in these reflective walls effectively neutralizes sound and, in other applications, can even absorb noise. When wood is used, the barriers are lighter, have greater strength-to-weight ratio than other building materials, and are much easier to build. They can be installed in four-metre lengths, with fewer posts and less disturbed ground. In most cases, heavy machinery is not needed, which is important in a tight urban setting. Wood costs less and offers a natural solution that delivers environmental benefits, especially when the products are from forests that meet third-party certification standards. With proper construction and treatment, wood barriers are resilient and durable, and are expected to last more than 30 years. The wood barriers are also successful projects on an aesthetic level, preferred by nearby residents who appreciate the natural appearance.

Wood Features

Cost Effective, Flexible

The final cost of the kind of wood-concrete hybrid system used in the Lower Mainland is about $110 per linear foot, or less than $14 a square foot. Wood is lighter, more flexible and easier to install; it uses fewer posts and does not require heavy machinery

Durable And Effective

Appropriate milling and conditioning ensures the wood lasts as long as other materials under similar conditions. The tongue-andgroove construction delivers an acoustical performance exceeding North American requirements of 20 to 30 sound transmission class. Wood barriers are tough: rocks and other highway debris are not as likely to cause damage and neutralize their effectiveness, and they are an excellent choice in colder climates where roads are treated with salt.

Natural, Attractive Choice

Wood provides a tangible connection to nature that is unmatched by other building materials, and offers an aesthetic appeal for both local residents and those travelling on the highway. When asked, 11 of 13 residents near the Alex Fraser Bridge perimeter road barrier chose the wood option.

Lower Environmental Impact

Wood is a natural choice for sustainable building construction; it has a lower energy and carbon footprint than most other products. The wood-concrete hybrid barriers save about one tonne of carbon for every five metres installed.

Underutilized Species

The Lower Mainland projects used hem-fir, an underutilized species that is a combination of British Columbia coastal hemlock and amabilis fir. Western Forest Products, which supplied the wood for the barriers, is exploring other ways to use hem-fir in custom products for export markets.