Performance Testing of Freeway Noise Barriers

Abstract

The results of the field evaluation along freeways in metropolitan Toronto show that these barriers are largely ineffective in reducing freeway traffic sound levels at nearby residences. Five different noise barrier types (an earth embankment, normal density and lightweight precast concrete panel walls, an aluminum wall, a plywood wall, and a gabion wall) are described, including materials, appearance, type of support and costs. The barriers, located midway between the houses and the pavement or at the highway shoulder, 60–140 ft (18–43 m) from the nearest houses, provided only 2–6 dba reduction at the first row of houses, 4 ft (1.2 m) above ground. Immediately behind the barriers, where the reductions are of little real benefit, reductions of 8–14 dba were achieved. Calculated reductions due to the barriers were overestimated rather than underestimated.