EXHIBIT 4-2_55A_BRISTOL WIDENING TECHNICAL STUDIES

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With the no -build alternative, the unattenuated 67 dBA contours will be located between 114 feet and 235 feet from the center- line. The unattenuated 62 dBA contours will be located between 351 feet and 739 feet from the Bristol Street centerline. With the build alternative, the unattenuated 67 dBA contours will be located between 116 and 236 feet from the centerline. The unattenuated 62 dBA contours will be between 352 and 739 feet from the centerline. The 62 dBA contour locations are provided within Table 4 -8 so that interior noise levels can be determined for comparison to the FHWA design criteria. Since FHWA allows a 10 dBA noise reduction factor for buildings with windows open, the location of the 62 Leq contour provides the point where interior noise levels of 52 dBA will occur when windows are open for those situations where there are no exterior activity areas and interior noise criteria apply. Sensitive Receptor Analysis The fifteen noise measurement locations (on thirteen lots) were analyzed for future noise impacts with three project alternatives and the no- project alternative ( see Figures 10 and 11 following page 4 -6). For each of the project alternatives, exterior noise levels were calculated for the no mitigation condition and with 6 -foot and 8 -foot barriers. In addition, the barrier height for a 5 dB attenuation over the no mitigation condition (minimum 6- foot wall), and the barrier height required to break line -of- sight to a 11.5 -foot high diesel exhaust stack was determined. After the widening of Bristol Street, some of the measurement locations will fall within the right -of -way for some of the project alternatives. Calculations of future noise Levels were not included for alternatives where the noise impacted structure is being removed. Since the front edge of the residential dwel- lings adjacent to measurement site #7 are on the right -of -way for alternative 2, there is no room for a noise barrier, and no barrier attenuation calculations were made. Finally, barrier attenuation calculations were not made for "no- mitigation" noise levels at or below 63 Leq. The noise impact from Bristol Street on residential areas falls into several categories. Many dwellings front onto Bristol Street with access directly onto Bristol Street, or with access to an alley in the back. The front yard noise impacts could be mitigated by constructing a barrier at the right -of -way, however pedestrian or pedestrian and vehicular access may be restricted by construction of a contiguous noise barrier. Dwellings with the side yard facing Bristol Street typically have front yard impacts. However, construction of a 6 -foot block wall protecting the front yard may reduce the visibility of motorists 4 -17