EXHIBIT 4-2_55A_BRISTOL WIDENING TECHNICAL STUDIES

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approaching Bristol Street and may also have aesthetic impacts. Several dwellings with side yards facing Bristol Street have rear yards enclosed by chain link fencing. The noise impacts on these rear yard activity areas will be similar to front yard impacts, but access conflicts will not be a consideration. Construction of a perimeter 6 -foot block wall at the right -of -way would reduce noise levels to acceptable Levels at these units. Several alternatives include taking a portion of school activity fields or playgrounds. For alternatives where the noise measure - ment location was within the right --of -way, the measurements were adjusted to reflect conditions ten feet behind the future right - of -way. Construction of a perimeter 6 -foot block wall at the right -of -way would reduce noise impacts to acceptable levels at outdoor activity areas. Second line receptors (ie. receptors impacted when abutting structures are removed) are often of concern adjacent to free- ways, but are generally not severely impacted in local roadway widening projects. Measurements at sites 12, 12A, 13, and 13A were made to assess the front and back yard impacts on a typical worst -case second line receptor. A field review of the sensitive noise receptors located adjacent to Bristol Street within the project area indicates exceedances of federal exterior noise criteria for approximately 167 front yard activity areas. Of these dwellings, 68 front onto Bristol Street with direct vehicular access, and 99 have vehicular access to a rear alley or to a side street. In addition, 7 of these dwellings have noise impacts in rear yard activity areas (six yards surrounded by chain link and one with no fencing). Table 4 -9 summarizes the noise levels at the fifteen typical locations evaluated along Bristol Street. The maximum one -hour equivalent noise levels for a 5.0 -foot receptor are shown for several scenarios including- 1. Existing noise levels at the outdoor activity area (account- ing for local attenuation by existing noise barriers); 2. Future design year noise levels without project implementa- tion (no project alternative); and 3. Future design year noise levels with the 3 proposed alterna- tives, including mitigation in the form of a 6 -foot or 8- foot barrier at the right -of -way. Also included are the barrier heights necessary to provide a 5 dBA attenuation from the "no- -mitigation' condition, and the height to break the line -of -sight between a 5.0 -foot receptor and a 11.5- - foot truck exhaust stack located at the equivalent source to r barrier distance) . 4--18