11 ATTACHMENT 04 - Laserfiche WebLink

- 18 - As the highest es tenor L,,,,,, was recorded to be 91 dBA. the interior maximum noise levels will be up to 81 dl3A. Ihus. the short-term rail noise levels vN..tl] he up to 31 dB in excess of the 5C d lintit for bedrooms and up to 26 dB in excess of the 55 dE3A limit for other living spaces. C. Vibration Levels To determine the leve s of vibration in the project structures. the PTA methodologies uses tbctcus for coupling loss or the aa) the house or structure is tied to the ground. hots the Moors resonate and the small amounts of vibrational energy that are lost as it travels throuhh the building. A slab on grade structure has no adjustment for coupling loss. A spread footing o- postlbeam foundation of a single-thailV reduces ground-borne vibration by 5 dB. A 6 dB increase is added for door resonances and a 2 dB -eduction per floor elevation it; subtracted. Therefore. tinder the highest ground s-ibratio 1 level caused by height trains of up to 79 dB on the bare .hound. the vibration lesels in the structure will he up to 83 VdB at the first floor and 81 VdB at the second floor. Thin. the vibration let els in slab on- grade homes are expected to he up to 3 d13 in excess of the 80 VdB criterion established by the FTA and used by the City of Pleasanton. Homes constructed on spread footings nr pustibeam Ibundatiens will have vibration levels of 78 VdB at the first Boor and 76 VdE3 at the second floor. The vibration levels. therefore. will be in compliance with the criterion. As shown by the above evaluations. exterior and interior noise exposure and interior noise level excesses will occur and mitigation measures will be required. Ground-borne yihraticn lesels are also expected to exceed the limits of the =TA criterion. Mitigation measures . ■ill be required for the noise and vibration level excesses. The recommended measures are described in Section II of this report.