Abstract:

Noise levels at receptor locations of varying distances and heights above a lake in Geneva, Switzerland were calculated. The traffic noise levels were computed for two bridge heights and six receiver heights. In addition, traffic noise levels for six distances (15-, 30-, 125-, 250-, 500-, and 1000-m) from the receptor to the near edge of the roadway were computed for each of the two bridge heights and six receiver heights. Four separate soundwall design scenarios were analyzed: (1) no soundwalls (base case); (2) two edge-of-shoulder plus one center divider reflective soundwalls, each 1 m in height; (3) two edge-of-shoulder reflective soundwalls, each 2 m in height; and (4) two edge-of-shoulder absorptive soundwalls, each 2 m in height. Comparison of the results shows that for all receptor distances and heights, noise levels would be lower for the 30-m-high bridge than for the 10-m-high bridge. This effect tends to diminish with receiver distance, however. The results also show that there are calculable and audible noise effect differences among the various antinoise barriers considered. For all receptor distances and heights, the soundwall design providing the highest degree of mitigation would be soundwall design alternative (4).