To establish a baseline against which to measure changes in the community noise environment over time, a noise modeling effort was performed, with year 2000 serving as the baseline year. Because traffic noise represents the dominant noise source in the community, the model focuses on traffic noise and the 24 hour ambient noise conditions resulting from this primary source.
Noise Exposure Contours for Baseline Figure SCS-4 shows 65 CNEL noise exposure contours for baseline year 2000. As Figure SCS-4 illustrates, the city's Principal and Minor Arterials represent the major source of traffic noise. Both commercial and residential uses along Principal and Minor Arterials (such as Atlantic Boulevard, Garfield Avenue, Pomona Boulevard, Garvey Avenue, and Graves Avenue) lie within the 65 CNEL noise contour. A number of residential neighborhoods are also exposed to traffic noise from Minor Arterials, Collector, and Local streets.
The city has little direct control over noise produced by transportation sources because state noise regulations for motor vehicle noise preempt local regulations. Since the city cannot control noise at the source, city noise programs focus on reducing the impact of transportation noise on the community.