Noise Technical Report for the Fore River Bridge Replacement Study

Transcription

1 Noise Technical Report for the Fore River Bridge Replacement Study Quincy and Weymouth, MA Prepared for: STV Incorporated 321 Summer Street Boston, MA Prepared by: 66 Long Wharf Boston, MA September 2010

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3 List of Definitions BACT... Best Available Control Technologies db... Decibels dba... A-Weighted Decibels FHWA... Federal Highway Administration HT... heavy trucks L10... noise level exceeded 10 percent of the time L90... noise level exceeded 90 percent of the time Leq... average noise level Lmax... Maximum noise level MT... Medium trucks mph... Miles per Hour RCNM... FHWA s Roadway Construction Noise Model (version 1.1) Type I... Projects that involve a substantial change in vertical or horizontal alignment Type II... Projects that involve noise abatement along an existing highway Type III... Projects that do not fall into either a Type I or Type II classification TNM... FHWA s Traffic Noise Model (version 2.5)

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5 Table of Contents 1. Introduction Human Perception of Noise Highway Noise Evaluation Criteria Monitoring Methodology Existing Conditions Noise Measurement Validation Operational Noise Levels Construction Noise Methodology Construction Noise Impacts Mitigation Attachments: Expanded Monitoring and Modeling Results List of Tables Table 1: FHWA and MassDOT Noise Abatement Criteria Table 2: Summary of Recommended Construction Noise Limits for the Project (dba) Table 3: Existing Peak-hour Noise Levels Measured at the Closest Sites in the Vicinity of the Fore River Bridge (in dba) Table 4 Summary of the Observed Traffic Data during the Short-term Measurements Table 5: Measured and Predicted Noise Levels at the Selected Receptors (in dba) Table 6: Predicted Future Peak Hour Leq Noise Levels from the Fore River Bridge (dba) Table 7: Estimated Construction Equipment for the Worst-Case Noise Activities (dba) Table 8: Summary of Prototypical Construction Noise Levels (dba) List of Figures Figure 1: Typical A-weighted Noise Levels Figure 2: Noise-Monitoring Sites in the Vicinity of the Fore River Bridge

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7 1. Introduction A noise assessment was prepared to document the potential impacts from the new bridge under the Build Alternative at sensitive receptors in the vicinity of the Fore River Bridge. The noise assessment was prepared in accordance with the Massachusetts Department of Transportation s (MassDOT) Noise Abatement Policy and the Federal Highway Administration s (FHWA) Highway Traffic Noise: Analysis and Abatement Guidance. The evaluation criteria, the existing conditions and the future traffic noise levels from the new bridge are described in the following sections. Based on the recently released Highway Traffic Noise: Analysis and Abatement Guidance [FHWA-HEP , July 2010], FHWA defines roadway projects using three classifications: Type I projects include the construction of a major highway in a new location or the physical alteration of an existing highway that substantially changes the horizontal or vertical alignment or increases the number of through traffic lanes. Type II projects are non-type I projects where MassDOT has undertaken a voluntary effort to construct feasible and reasonable noise barriers along existing interstate highways under its jurisdiction, when funding priorities allow. Type II projects do not apply to state routes or local roads such as Route 3A. Type III projects (such as repaving or bridge rehabilitation, replacement or reconstruction) do not meet the classifications of a Type I or Type II project. Type III projects do not require a noise analysis. The proposed permanent replacement bridge roadway elevation is predicted to be approximately 10 feet higher at the center than the current temporary bridge, but no additional lanes that would increase the roadway capacity. MassDOT considers this change of 17 percent a substantial increase in vertical alignment. Therefore, the following noise assessment was conducted in accordance with the FHWA and the MassDOT Type I Noise Abatement Policy guidelines. 2. Human Perception of Noise Noise is unwanted sound and, by this definition, the perception of noise is a subjective process. Several factors affect the actual level and quality of sound (or noise) as perceived by the human ear and can generally be described in terms of loudness, pitch (or frequency), and time variation. The loudness or magnitude of noise determines its intensity and is measured in decibels (db) that may range from below 40 decibels (the rustling of leaves) to over 100 decibels (a rock concert). Pitch describes the character and frequency content of noise such as the very low rumbling noise of stereo sub-woofers, or the very high-pitched whistle noise. Finally, the time variation of some noise sources can be characterized as continuous, such as a building ventilation fan; intermittent, such as for a train passby; or impulsive, like pile driving construction activities. Various sound levels are used to quantify noise from transit sources, including a sound's loudness, duration, and tonal character. For example, the A-weighted decibel (dba) is commonly used to describe the overall noise level because it represents the human ear's response to audible frequencies. Because the decibel is based on a logarithmic scale, a 10- decibel increase in noise level is generally perceived as a doubling of loudness, while a 3-1

8 decibel increase in noise is just barely perceptible to the human ear. Typical A-weighted sound levels from highway and other common sources are shown in Figure 1. Several A-weighted noise descriptors are used to determine impacts from highway related sources. These include the L max, which represents the maximum noise level that occurs during an event such as a car or truck passby; the L eq, which represents a level of constant noise with the same acoustical energy as the fluctuating noise levels observed during a given interval, such as one hour; and the L dn, which is the 24-hour day-night noise level that includes a 10- decibel penalty for all nighttime activity between 10:00 PM and 7:00 AM. Figure 1: Typical A-weighted Noise Levels 2

9 3. Highway Noise Evaluation Criteria The following noise criteria were evaluated for both traffic operations in the future Design year and temporary construction activities. Traffic Noise Potential negative impact from traffic noise is assessed on the basis of predicted noise levels approaching or exceeding the Federal Highway Administration s (FHWA) Noise Abatement Criteria (NAC). As shown in Table 1, the NAC for residences and similar sensitive exterior receivers is a one-hour equivalent sound level [L eq (h)] of 67 dba during the peak traffic hour. Table 1: FHWA and MassDOT Noise Abatement Criteria Activity Category A B C L eq (h)* 57 (Exterior) 67 (Exterior) 72 (Exterior) Description of Activity Category D -- Undeveloped lands. Lands on which serenity and quiet are of extraordinary significance and serve an important public need and where the preservation of those qualities is essential if the area is to continue to serve its intended purpose. Picnic areas, recreation areas, playgrounds, active sports areas, parks, residences, motels, hotels, schools, churches, libraries, and hospitals. Developed lands, properties, or activities not included in Categories A or B above. 52 Residences, motels, hotels, public meeting rooms, schools, churches, libraries, E (Interior) hospitals, and auditoriums. * L eq (h) is an energy-averaged, one-hour, A-weighted sound level in decibels (dba). Source: 23 CFR Part 772, Procedures for Abatement of Highway Traffic Noise and Construction Noise. The MassDOT Noise Abatement Policy has defined approaching as within one decibel of the FHWA NAC for residential or other similar sensitive land use areas. In addition, MassDOT defines a substantial increase as 10 dba greater than existing noise levels. These noise levels are used by MassDOT to evaluate the need for noise mitigation measures due to highway improvements. FHWA guidelines and the MassDOT Noise Abatement Policy indicate that abatement should be considered if the noise criteria described above are exceeded. However, the abatement measures must be both feasible and reasonable to be recommended for implementation. According to the MassDOT Noise Abatement Policy, feasibility refers to engineering considerations (e.g., can a barrier be built given the topography of the location; can a substantial noise reduction of five decibels be achieved given certain access, drainage, safety, or maintenance requirements; are other noise sources present in the area, etc.). For instance, maintaining access to properties often requires gaps in barriers at entrance and exit driveways and reduces their effectiveness to the point that substantial noise reduction is not feasible. Reasonableness refers to a barrier s cost effectiveness and the level of public support. MassDOT considers a noise barrier to be cost effective if, based on the Cost Effectiveness Index (CEI), it costs $2,700 per decibel reduction per benefited receptor or less. Benefited 3

10 receptors include all residences in the study zone attaining at least a five-decibel reduction in noise, regardless of whether that residence was considered an impacted receptor or not. For any noise barrier to be considered further for construction, public support must include at least two-thirds of all first-row receptors that are in favor of a barrier. Construction Noise The Massachusetts Department of Environmental Protection (DEP) noise limits [Division of Air Quality Control, 310 CMR 7.10] were used to establish thresholds for construction-period noise impacts applicable to this project, as summarized in Table 2. Unlike other construction criteria (such as those used on the Central Artery/Tunnel Project or the City of Boston), which have higher absolute noise limits, the DEP noise limits are based on a threshold equal to 10 decibels above the existing background level as measured. The background noise level (defined as the noise level exceeded 90 percent of the time or L90) was measured over a 24-hour period at each of the selected receptor locations. The DEP criteria also include a 5-decibel adjustment for equipment with a distinct pure-tone noise such as fans or pumps. A pure tone occurs when any octave band center frequency sound pressure level exceeds the two adjacent center frequency sound pressure levels by 3 decibels or more. The DEP guidelines were selected for the following reasons: The average noise limits (or Leq) are more stringent than those developed for the Central Artery/Tunnel (CA/T) Project. The noise limits used for the CA/T are absolute limits which are more applicable for dense urban areas; and, The maximum noise limits (or Lmax) are more stringent than those developed for the CA/T project or the City of Boston. MassDOT intends to incorporate the recommended noise limits into the contract specifications to be used by the contractor to demonstrate compliance through periodic submittal of noise control plans and field monitoring. Predicted or measured noise levels that exceed or do not comply with the recommended construction noise limits (i.e., Table 2 and pure tone condition) would be required to be mitigated by the contractor. Table 2: Summary of Recommended Construction Noise Limits for the Project (dba) Receptor Long-term (L eq (h) Short-term (L max ) ID Description Daytime Evening Nighttime Daytime Evening Nighttime M1 53 St. Germaine Street M2 75 Kings Cove Beach Road M3 101 Bridge Street (Route 3A) M4 21 Dee Road M5 50 Monatiquot Street The time periods include daytime (7 AM 6 PM), evening (6-10 PM) and nighttime (10 PM 7 AM). 4

11 The Town of Weymouth does not set limits on construction noise but has adopted the DEP noise limits. Similarly, the City of Quincy restricts construction activities to the daytime period from 7:00 AM to 6:00 PM in accordance with Section (Noise Operation of plant or machinery Restrictions) but does not establish noise limits for construction activities. MassDOT is exempt from local bylaws. 4. Monitoring Methodology To determine the existing noise levels at sensitive receptors in the vicinity of the Fore River Bridge, a noise-monitoring program was conducted at several representative locations shown in Figure 2 and described in Table 3. Hourly equivalent A-weighted noise levels [or L eq (h) in dba] were measured at five representative receptors during the peak and off-peak periods of the day according to the MassDOT methodology. The noise measurements document existing noise sources in the area such as background traffic along Route 3A, for example, and other existing activity in the immediate area. The background noise measurements were conducted on September 23-25, 2009 at Sites M1 to M4 and on July 12-13, 2010 at Site M5. During the noise monitoring period, concurrent traffic volumes and speeds were also documented. These input data, along with the roadway and terrain geometries, were used to develop a software prediction model. Following MassDOT s guidelines and FHWA s requirements, the Federal Highway Administration s (FHWA) Traffic Noise Model (TNM Version 2.5) was used to replicate the measured noise levels in the field and thereby validate the prediction model see Section 6 for a discussion of predicted noise levels). The sound-level meters that were used to measure current noise conditions (such as the Larson Davis Model 820) meet or exceed the American National Standards Institute (ANSI) standards for Type I accuracy and quality. The sound-level meters were calibrated (with a Larson Davis Model CAL200) before and after each measurement. All measurements were conducted according to ANSI Standard S , Measurement of Sound Pressure Levels in Air. All noise levels were reported in A-weighted decibels (dba), which best approximate the sensitivity of human hearing. 5. Existing Conditions As shown in Table 3, measured hourly average noise levels [L eq (h)] for the noisiest hour range from 54 dba at Receptor M5 (residences along Monatiquot Street in Weymouth) to 55 dba at Receptors M2 and M4 (residences along Kings Cove Beach Road in Weymouth and Dee Road in Quincy, respectively) to 67 dba at Receptor M3 (residences along Bridge Street in Weymouth). The lower levels are representative of truly ambient conditions influenced by marine traffic, adjacent facilities such as the Fore River Station power plant, and natural sounds only with an occasional car passby in the neighborhood. The higher levels measured at Site M3 reflect vehicular traffic accessing the Fore River Bridge along Route 3A. All of the existing noise levels are typical of suburban land-uses along active transportation corridors. Based on the results of the baseline noise monitoring, residences adjacent to Route 3A (represented by Receptor M3) currently exceed (or are equal to or approach within one decibel) the FHWA/MassDOT noise abatement criterion of 67 dba. Therefore, within the FHWArecommended distance of 500 feet of the project study area, traffic noise levels at four residences currently exceed the FHWA noise criterion of 67 dba. 5

12 Table 3: Existing Peak-hour Noise Levels Measured at the Closest Sites in the Vicinity of the Fore River Bridge (in dba) ID Receptor Description Location Land-Use Category Existing Noise, L eq (h) M1 53 St. Germaine Street Quincy B (Residential) 58 M2 75 Kings Cove Beach Road Weymouth B (Residential) 55 M3 101 Bridge Street (Route 3A) Weymouth B (Residential) 67 M4 21 Dee Road Quincy B (Residential) 55 M5 50 Monatiquot Street Weymouth B (Residential) 54 1 Existing baseline noise levels were measured during various periods of the day to document the worst-case noise hour. Source: AECOM, Boston, MA, September Expanded results of the existing noise levels measured in the community are shown in the attachments to this technical report. For example, the noise levels by period of the day are summarized in Table A.1. Similarly, hourly variations in the background noise levels are shown graphically in Figures A.1 to A.5 for Sites M1 to M5, respectively. Source: AECOM, Boston, MA, September Figure 2: Noise-Monitoring Sites in the Vicinity of the Fore River Bridge 6

13 6. Noise Measurement Validation A noise monitoring program was conducted in September 2009 and July 2010 to document existing noise levels in the community. The noise monitoring program included both long-term and short-term measurements. The long-term noise measurements were collected continuously over a 24-hour period at five receptor sites selected to be representative of the various neighborhoods in the vicinity of the Fore River Bridge. The short-term noise measurements were conducted to correlate existing traffic with existing noise levels. As shown in Table 4, concurrent traffic information was collected at Sites M3 and M4 during the short-term noise measurements. Consistent with the MassDOT Noise Abatement Policy, these data were used to help validate the Federal Highway Administration s (FHWA) Traffic Noise Model (TNM) prediction software. Since Sites M1, M2 and M5 are too far away from Route 3A, their cumulative noise exposure is due only partially to traffic noise but other non-transportation sources as well. Therefore, measured noise levels at ambient sites cannot be validated using traffic volumes alone. Model validation is intended for sites located along roadways (such as Sites M3 and M4). Table 4: Summary of the Observed Traffic Data during the Short-term Measurements Site Location Period Date Time CARS 1 MT 1 HT 1 mph 1 M3 101 Bridge Street, Weymouth Peak 09/24/09 5:25-5:45 PM M4 21 Dee Road, Quincy Peak 09/23/09 3:50-4:10 PM Traffic data was not collected at Sites M1, M2 and M5 since they are too far away from Route 3A. As a result, their cumulative noise exposure is due to both roadway and other non-transportation sources. Measured noise levels at ambient sites cannot be validated using traffic volumes alone. 2 Observed traffic data includes cars and pick-ups (CARS), medium trucks with two axles (MT), heavy trucks with three or more axles (HT), and speed estimated in miles per hour (mph). Source: AECOM, Boston, MA, September As shown in Table 5, the model validation exercise resulted in good correlation for monitoring sites (Site M3 and M4) whose background noise levels are dominated by existing traffic. For example, at Site M3 (residences along Bridge Street in Weymouth east of the bridge), modeled noise levels are predicted to range from 1 to 3 decibels less than the measured noise levels using the same traffic conditions and site geometry. Similarly, modeled noise levels at Site M4 (residences along Dee Road in Quincy west of the bridge) are predicted to be only 1 decibel above the measured noise levels using the same traffic conditions for Site M4. The noise monitoring sites are shown graphically in Figure 2. However, at the ambient sites not directly affected by arterial traffic along Route 3A, the modeled noise levels cannot accurately predict the observed noise levels measured in the field. Due primarily to other non-roadway related activities such as marine activity (e.g., ferry boats), local street traffic and other non-traffic sources, the modeled noise levels at ambient sites M1 and M2 are predicted to be 6 to 16 decibels below the measured noise levels. This difference is not an artifact of the prediction model but due rather to the influence from other typical noise sources in the immediate vicinity of the receptors. Similarly, since Site M5 is also an ambient location not dominated by traffic noise, the traffic noise model could not be validated at this site. 7

14 Table 5: Measured and Predicted Noise Levels at the Selected Receptors (in dba) Site Location Period Measured M1 M2 M3 53 St. Germaine Street 75 Kings Cove Beach Road 101 Bridge Street TNM Prediction Difference Peak Peak Peak M4 21 Dee Road Peak Description Ambient sites not in the immediate proximity to roadways cannot be validated because their overall noise exposure is partially due to traffic but also other non-traffic sources (such as marine). Good correlation due to close proximity to traffic along Route 3A. M5 50 Monatiquot Street Ambient Ambient site not dominated by traffic cannot be validated. 1 The measured peak-hour Leq(h) noise levels reported here were collected during the monitoring program for model validation purposes only. As a result, depending on the timing of the validation measurements, they may be different from the overall average background noise levels reported in Table A.1. 2 Unlike houses along roadways, noise levels at ambient sites are based on a contribution from many indirect non-traffic sources in the community. As a result, the TNM noise model at ambient sites cannot be validated with actual traffic volumes. Source: AECOM, Boston, MA, September Operational Noise Levels Based on the results of the validation exercise described in Section 6 ( Noise Measurement Validation ), the FHWA TNM prediction model was modified to reflect future traffic conditions in the Design Year To be conservative, the prediction methodology utilized maximum peakhour traffic volumes with average free flow travel speed equal to the speed limit. (Details of the traffic volumes and speeds are shown in Attachment Table A.2.) Due to the large bodies of water between most of the residences and the roadway traffic along Route 3A, reflective ground effects typical of water were utilized to determine the ground-attenuation effects between the source and receivers. The vehicle mix utilized in the prediction modeling analyses reflects current traffic conditions, since it is not expected to vary substantially in the future. Maximum peak-hour noise levels [Leq(h)] were predicted for both the 2010 Existing and the future conditions under the 2030 No Build and Build Alternatives. The noise levels predicted for the 2010 Existing Condition are different from the measured noise levels because they are based on the same input data that were used to develop the future traffic volumes. As shown in Table 6, peak-hour noise levels [L eq (h)] under the 2030 Build Alternative are predicted to range from 50 dba at Sites M1, M2 and M5 to 61 dba at Site M4 west of the bridge to 70 dba at Site M3 along Bridge Street. The Existing and future No Build noise levels at Sites M1, M2 and M5 reflect a three-decibel adjustment to account for the higher noise created by the joints in the existing bridge s road surface deck. 1 The predicted noise levels under the Build Alternative are predicted to be lower due to the new smooth asphaltic concrete surface installed on the new bridge that would be free of any joints or other roadway imperfections that contribute to higher tire-pavement noise under the Existing and No Build Conditions. 1 The actual noise level (due to the joints in the steel plates used for the existing bridge s deck) was observed to be even higher. However, a conservative estimate was applied to account for this additional noise source from the existing bridge. 8

15 Table 6: Predicted Future Peak Hour L eq Noise Levels from the Fore River Bridge (dba) Receptor Dwelling Predicted Noise Levels (dba) ID Description Location Land-Use Category Units Existing No Build Build 3 M1 53 St. Germaine Street Quincy B (Residential) M2 75 Kings Cove Beach Road Weymouth B (Residential) M3 101 Bridge Street (Route 3A) Weymouth B (Residential) M4 21 Dee Road Quincy B (Residential) M5 50 Monatiquot Street Weymouth B (Residential) The number of dwelling units estimated at each site represents the number of equivalent land-uses with the same predicted noise levels as the selected representative receptor site. 2. A three-decibel adjustment was applied to the existing and future No Build noise levels at Sites M1, M2 and M5 to account for the additional noise created by the gaps and loose plates of the temporary bridge. 3. The Build noise levels represent the replacement of the current temporary Bridge with a permanent bridge that includes a smooth asphaltic road surface, which would be quieter. Source: AECOM, Boston, MA, September Except for Site M3 along Bridge Street, none of the other receptor locations are predicted to exceed the MassDOT noise abatement criterion (NAC) of 67 dba for Category B land uses or for substantial (greater than 10 dba) increases. The noise levels along Bridge Street (Route 3A) are affected by the existing traffic volumes and by the projected growth in traffic between now and The Preferred Alternative will not have a negative impact on the noise levels for the impacted receptors because the replacement bridge is functionally equivalent to the temporary bridge. Therefore, the replacement bridge will not increase traffic and, as a result, will also not increase noise levels by itself. In fact, the new bridge will be quieter than the existing, since it will have a smooth roadway surface instead of a steel panel deck like the temporary bridge, thus having a beneficial effect. As shown in Table 6, maximum hourly noise levels at Site M3 (residences adjacent to Bridge Street east of the bridge) are predicted to exceed the MassDOT noise abatement criterion of 67 dba. Each of the four residences where existing and future noise levels are predicted to exceed the NAC of 67 dba is located on Bridge Street (Route 3A) in Weymouth within 500 feet of the project limits. The noise levels at these receptors are dominated by roadway traffic along Bridge Street rather than traffic noise from the bridge itself. 8. Construction Noise Methodology Based on information provided by STV regarding construction activities and equipment for the construction of the Fore River Replacement Bridge, two worst-case prototypical construction scenarios were evaluated to better gauge the potential for noise impacts. The resultant noise levels from the selected construction scenarios were predicted using the Federal Highway Administration s (FHWA) Roadway Construction Noise Model (RCNM), currently version 1.0. The RCNM included the following input data to develop peak construction noise levels: 9

16 Equipment type Usage factor (the percent of time the equipment is used) Maximum noise levels (specification and actual) Receptor distance Estimated shielding For this analysis, the equipment and operating information used to develop the prototypical noise levels are summarized in Table 7. Two construction scenarios were selected to represent the potentially worst-case noise conditions including: Scenario #1 Construct Approach and Flanking Spans, Perform Concrete Removal Scenario #2 Construct Dolphins and Fenders, Install Sheeting for Dolphins The results of the construction impact assessment for these two worst-case construction scenarios are described in the following section. Table 7: Estimated Construction Equipment for the Worst-Case Noise Activities (dba) Construction Equipment FHWA RCNM 1 Impact Usage L max Scenario Description Equivalent Device Factor (dba) Scenario #1 Construct Approach & Flanking Spans - Concrete Removal Scenario #2 Construct Dolphins and Fenders - Install Sheeting for Dolphins Compressor Compressor (air) No 40% 77.7 Hydraulic Impact Ram Hydra Break Ram Yes 10% 90.0 Jackhammer Jackhammer Yes 20% 88.9 Dump Trucks Dump Truck No 40% 76.5 Tugs All Other Equipment > 5 HP No 50% 85.0 Pile Driving Rig Impact Pile Driver Yes 20% Crane Crane No 16% 80.6 Compressor Compressor (air) No 40% 77.7 Impact Wrenches Pneumatic Tools No 50% 85.2 Tractor Trailer Dump Truck No 40% Construction equipment, usage factors and reference noise levels are based on default equipment types included in the FHWA Roadway Construction Noise Model (RCNM). Source: AECOM, Boston, MA, September Construction Noise Impacts While the area immediately abutting the Fore River Bridge is primarily industrial, there are residential neighborhoods in proximity to the bridge that may experience noise impacts during construction (see Section of the Environmental Assessment for a discussion of communities and neighborhoods in proximity to the bridge). Noise related to construction would result from the operation of heavy equipment needed to construct the bridge piers, superstructure, walls, fender system and dolphins, and roadway surfaces associated with the replacement bridge. Noise from demolition activities associated with the construction would 10

17 also result in construction period noise. Noise produced by construction equipment working on the project would occur with varying intensity and duration during the various phases of construction. Overall project construction is estimated to be four years. Because of the different phases of construction and the large project area, no single location would be anticipated to experience construction noise impacts for the entire duration of the project. Construction truck travel along the designated truck route (see Figure of the Environmental Assessment) is not anticipated to result in a noise impact as Route 53 and Route 18 are currently state-designated truck routes. Based on the results of the FHWA construction noise modeling (RCNM), maximum peak-hour noise levels from Scenario #1 (Concrete Removal) are predicted to range from 50 dba at Site M2 (residences along Kings Cove Road in Weymouth) to 55 dba at Sites M3 (residences along Route 3A immediately adjacent to the bridge) and M5 (residences along Monatiquot Street just south of the bridge). As shown in Table 8, these levels are not predicted to exceed the more stringent nighttime impact limits from 10:00 PM to 7:00 AM. Table 8: Summary of Prototypical Construction Noise Levels (dba) Receptor Dist. (ft) ID Description L eq Long-term (L eq ) Short-term (L max ) Project DEP Noise Limits Project DEP Noise Limits Daytime/ Evening Nighttime L max Daytime/ Evening Nighttime Scenario #1 Construct Approach & Flanking Spans, Concrete Removal M1 53 St. Germaine Street, Quincy 1, / /75 70 M2 75 Kings Cove Beach Road, Weymouth 2, / /70 65 M3 101 Bridge Street (Route 3A), Weymouth 1, / /80 75 M4 21 Dee Road, Quincy 1, / /70 65 M5 50 Monatiquot Street 1, / /70 65 Scenario #2 Construct Dolphins and Fenders, Install Sheeting for Dolphins M1 53 St. Germaine Street, Quincy 1, / /75 70 M2 75 Kings Cove Beach Road, Weymouth 2, / /70 65 M3 101 Bridge Street (Route 3A), Weymouth 1, / /80 75 M4 21 Dee Road, Quincy 1, / /70 65 M5 50 Monatiquot Street 1, / /70 65 NB: The time periods include daytime (7 AM 6 PM), evening (6-10 PM) and nighttime (10 PM 6 AM). Source: AECOM, Boston, MA, September However, maximum peak-hour noise levels from Scenario #2 (Install Sheeting for Dolphins) are predicted to range from 60 dba at Site M2 (residences along Kings Cove Road in Weymouth) to 65 dba at Site M3 (residences along Route 3A immediately adjacent to the bridge) and Site M5 (residences along Monatiquot Street just south of the bridge). As shown in Table 8, these levels are all predicted to approach or exceed the proposed impact limits for the daytime, 11

18 evening and nighttime periods at the representative receptor sites. The predicted exceedances are due to the use of an impact pile driver to bury the sheeting for the coffer-dam around the dolphin construction. 10. Mitigation Noise control measures are discussed separately for operations and construction. Operations As shown in Table 6, maximum hourly noise levels at Site M3 (residences adjacent to Bridge Street east of the bridge) in 2030 are predicted to exceed (or approach within one decibel) the MassDOT noise abatement criterion of 67 dba. This is a result of the overall increase in traffic growth on Route 3A in 2030 that is projected to occur with or without the replacement bridge. Each of the four residences (represented by Site M3) where existing and future noise levels are predicted to exceed the NAC of 67 dba is located in Weymouth over ¼ mile from the Fore River Bridge center point. The noise levels at these receptors are dominated by roadway traffic along Bridge Street rather than traffic noise from the bridge itself. However, although some road improvements are proposed for the approach roadways on both sides of the bridge to accommodate a taller bridge, no modifications are proposed along Bridge Street in the vicinity of the adversely affected receptors. FHWA guidelines and the MassDOT Noise Abatement Policy indicate that abatement should be considered if the noise criteria described previously are exceeded for a Type I project. According to the MassDOT Noise Abatement Policy, feasibility refers to engineering considerations (e.g., can a noise barrier be built given the topography of the location; can a substantial noise reduction be achieved given certain access, drainage, safety, or maintenance requirements; are other noise sources present in the area, etc.). For instance, maintaining access to commercial properties often requires gaps in noise barriers at entrance and exit driveways and reduces their effectiveness to the point where substantial noise reduction is not feasible. Reasonableness refers to a barrier s cost effectiveness and the level of public support. MassDOT considers a noise barrier to be cost effective if, based on the Cost Effectiveness Index (CEI), it costs $2,700 per decibel reduction per benefited receptor or less. Benefited receptors include all residences in the study zone attaining at least a five-decibel reduction in noise, regardless of whether that residence was considered an impacted receptor or not. For any noise barrier to be considered further for construction, at least two-thirds of all first-row receptors must be in favor of a barrier. In accordance with the FHWA noise policy CFR 772, the following noise abatement measures were evaluated to reduce the traffic noise impacts. (1) Traffic management measures (such as traffic control devices and signing for prohibition of trucks, time-use restrictions for trucks, modified speed limits, and exclusive land designations) would not be feasible on a major public arterial such as Route 3A that requires open access for truck deliveries; (2) The alteration of horizontal and vertical alignments would also not be feasible since Route 3A is currently used for driveway access to the residences and retail stores. In fact, the Fore River Replacement Bridge has taken special measures to minimize any disturbance of the current roadway profile and horizontal alignment so as to minimize any inconveniences or economic impacts on the community; 12

19 (3) The acquisition of property rights (either in fee or lesser interest) for construction of noise barriers would not be reasonable since all properties along Route 3A would still require driveway access thereby degrading the acoustical properties of the barriers; (4) The construction of noise barriers (including landscaping for aesthetic purposes) whether within or outside the highway right-of-way are not feasible because the openings required for driveway access would degrade the acoustical performance of the barriers; (5) The acquisition of real property to serve as a buffer zone to preempt development which would be adversely impacted by traffic noise is also not feasible since the only available buffer zone is the public sidewalk, which would not effectively reduce the traffic noise. There is no room for any future development between the affected residences and Route 3A; and, (6) Sound insulation of public-use or nonprofit institutional structures does not apply since all of the impacted properties are private residences. Construction Since pile drivers and other impact devises may be used during demolition and construction of the replacement bridge, there is a potential for noise impacts during certain construction activities. As a result, the contractor will be required develop noise control measures to minimize the impact on the community and to achieve compliance with the project impact criteria. To reduce temporary construction noise impacts that are expected in the vicinity of the Fore River Bridge, several good housekeeping practices are recommended. The selected contractor would be required to provide a Noise Control Plan indicating how the noise standards stated in the project specifications will be met. Details of the Noise Control Plan requirements would be defined in the contract specifications. Requiring contractors to use the best available control technologies (BACT) would limit excessive noise and vibration impacts to minimum levels dictated by the available equipment. For example, mitigation measures that may be evaluated include substituting quieter equipment such as vibratory pile drivers, scheduling of the loudest equipment to the least sensitive period of the day, or employing temporary equipment shrouds. Due to the uniqueness of building a bridge over water, applying standard noise control measures typically used on land would neither be practical nor effective. For example, enclosures may be more appropriate for stationary equipment such as compressors and generators rather than mobile equipment such as pile drivers located on barges. Other potential control measures to minimize the noise and vibration impacts in the community that could be incorporated into the construction process include: Establish equipment and material staging areas away from sensitive receptors; Limit pile driving to daylight hours; and, Adequately notify the public of construction operations and schedules. Methods such as construction-alert publications could be used to handle complaints quickly. 13

20 Attachments: Expanded Monitoring and Modeling Results Table A.1: Summary of Existing Leq(h) Noise Levels Measured at Representative Receptor Locations in the Vicinity of the Fore River Bridge (in dba) Figure A.1: 24-Hour Existing Noise Levels Measured at Site M1 (Residence at 53 St. Germaine Street, Quincy) on October 2, Figure A.2: 24-Hour Existing Noise Levels Measured at Site M2 (Residence at 75 Kings Cove Beach Road, Weymouth) on October 2, Figure A.3: 24-Hour Existing Noise Levels Measured at Site M3 (Residence at 101 Bridge Street, Weymouth) on October 2, Figure A.4: 24-Hour Existing Noise Levels Measured at Site M4 (Residence at 21 Dee Road, Quincy) on October 2, Figure A.5: 24-Hour Existing Noise Levels Measured at Site M5 (Residence at 50 Monatiquot Street, Weymouth) on July 12, Table A.2: Peak-Hour Traffic Data Used in the Prediction Modeling Analyses Figure A.6: Calibration Certificate for the Noise Monitoring Equipment Type I Microphone. Figure A.7: Calibration Certificate for the Noise Monitoring Equipment Sound Level Meter. Figure A.8: Calibration Certificate for the Noise Monitoring Equipment Signal Pre- Amplifier. Figure A.9: Calibration Certificate for the Noise Monitoring Equipment Calibrator. 14

21 Table A.1: Summary of Existing L eq (h) Noise Levels Measured at Representative Receptor Locations in the Vicinity of the Fore River Bridge (in dba) ID Location Period Metric 1 AM Peak M1 53 St. Germain Street (Quincy) 9/23/09 M2 75 Kings Cove Beach Road (Weymouth) 9/24/09 M3 101 Bridge Street (Weymouth) 9/24/09 M4 21 Dee Street (Quincy) 9/23/09 M5 50 Monatiquot Street 7/12/10 Midday Off-Peak PM Peak Minimum Maximum Mean Minimum Maximum Mean Minimum Maximum Mean Minimum Maximum Mean Minimum Maximum Mean The minimum, maximum and mean noise levels are reported for different periods of the day including: AM Peak (7 9 AM), midday off-peak (9 AM 4 PM) and PM peak (4 6 PM). Source: AECOM, Boston, MA, September

22 Figure A.1: 24-Hour Existing Noise Levels Measured at Site M1 (Residence at 53 St. Germaine Street, Quincy) on September 23,

23 Figure A.2: 24-Hour Existing Noise Levels Measured at Site M2 (Residence at 75 Kings Cove Beach Road, Weymouth) on September 24,

24 Figure A.3: 24-Hour Existing Noise Levels Measured at Site M3 (Residence at 101 Bridge Street, Weymouth) on September 24,

25 Figure A.4: 24-Hour Existing Noise Levels Measured at Site M4 (Residence at 21 Dee Road, Quincy) on September 23,

26 Figure A.5: 24-Hour Existing Noise Levels Measured at Site M5 (Residence at 50 Monatiquot Street, Weymouth) on July 12,

27 Table A.2: Peak-Hour Traffic Data Used in the Prediction Modeling Analyses Street AADT AM Pk-Hr PM Pk-Hr AADT AM Pk-Hr PM Pk-Hr Washington Street (West of Rotary) 31,881 2,171 2,330 37,389 2,546 2,733 Fore River Bridge 31,416 2,314 2,331 36,844 2,714 2,734 Bridge Street (East of Fore River) 25,204 2,010 1,737 29,558 2,357 2,037 Frontage Road Westbound (East of Rotary) Frontage Road Eastbound (East of Rotary) Shipyard Drive (South of Rotary) Dee Road (North of Rotary) The reported traffic volumes include annual average daily traffic (AADT), and morning and afternoon peak-hour (AM and PM Pk-Hr, respectively) traffic periods. Source: Howard Stein Hudson Associates, Memorandum: Fore River Bridge Construction Period Lane Use, May 29,

28 Figure A.6: Calibration Certificate for the Noise Monitoring Equipment Type I Microphone. 22

29 Figure A.7: Calibration Certificate for the Noise Monitoring Equipment Sound Level Meter. 23

30 Figure A.8: Calibration Certificate for the Noise Monitoring Equipment Signal Pre-Amplifier. 24

31 Figure A.9: Calibration Certificate for the Noise Monitoring Equipment Calibrator. 25