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Because fewer than 5% of the population would typically be awakened by an interior SEL of less than 65 dB, the computed worst-case level of 55 dB SEL for windows in the closed positions is not anticipated to result in adverse noise impacts relative to sleep disturbance, even with the relatively infrequent usage of Jake Brakes along the project corridor. As a result, noise impacts associated with nighttime passages of project-related truck traffic on residents sleeping with windows closed are predicted to be less than significant. Sleep Disturbance Impacts due to Nighttime Project-Related Truck Traffic — Bedroom Windows Open With windows of the nearest residences along the project corridor in the open position, the project will present a higher probability of sleep disturbance. As noted previously, where interior SEL values exceed 65 dB, the potential for sleep disturbance has been shown to be approximately 5%. The probability of interior noise levels within open-window bedrooms of residences along East River Road actually exceeding 65 dB SEL during nighttime passages of heavy trucks depends on several factors. Those factors include the typical SEL value generated by the truck passage, the distance between the exterior building fagade of the bedroom and the roadway, the orientation of the fagade(s) upon which the open bedroom window(s) are located relative to the roadway, and the degree of shielding of the roadway by intervening orchards, structures or barriers. Typical residential construction can be expected to provide approximately 10 dB of noise reduction with windows in the open position, assuming the open window faces the noise source in question. However, open windows with side and rear-facing exposure to the noise source can be expected to provide approximately 15 and 20 dB exterior to interior noise reduction, respectively. This is because the windows with side-facing exposure to the noise source have a much more limited "view" of the noise source (approximately 50%), and windows facing away from the source have no view of the source at all. As a result, sound entering the bedroom through such open window orientations must do so by a more circuitous route than sound entering through a window which directly faces the noise source (East River Road in this case). Given an exterior SEL of 79 dB at a distance of 60 feet from the centerline of East River Road with project trucks operating with the optimized noise-reduction procedures discussed previously, the interior SELs within the nearest residences were calculated. The results of those calculations are shown in Table 8 for a range of distances from the roadway and window configurations. Environmental Norse Analysis Munn&Perkins Expanded Hours of Operations—San Joaquin County Page 32