NOISE AND VIBRATION TECHNICAL REPORT

Transcription

1 NOTHWEST I-75/I-575 COIDO ALTENATIVES ANALYSIS/ DAFT ENVIONMENTAL IMPACT STATEMENT NOISE AND VIBATION TECHNICAL EPOT prepared for: FEDEAL HIGHWAY ADMINISTATION and GEOGIA DEPATMENT OF TANSPOTATION in cooperation with: FEDEAL TANSIT ADMINISTATION and GEOGIA EGIONAL TANSPOTATION AUTHOITY prepared by: Parsons Brinckerhoff April 2007

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3 NOTHWEST I-75/I-575 COIDO ALTENATIVES ANALYSIS / DAFT ENVIONMENTAL IMPACT STATEMENT NOISE AND VIBATION TECHNICAL EPOT PEPAED FO: Federal Highway Administration and Georgia Department of Transportation IN COOPEATION WITH: Federal Transit Administration, and Georgia egional Transportation Authority PEPAED BY: Parsons Brinckerhoff April 2007 NHS (919), CSNHS (417), CSNHS (418), CSNHS (419), NH-575-1(28), NH-73-3(242), CSMSL (404), The preparation of this document has been financed by the Georgia Department of Transportation and the Georgia egional Transportation Authority through funding assistance provided by the Federal Highway Administration (FHWA) and the Federal Transit Administration (FTA) of the United States Department of Transportation.

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5 Table of Contents 1. INTODUCTION Project Area Purpose and Need Alternatives No- Alternative HOV/TOL Alternative HOV/TOL/TSM Alternative HOV/TOL/BT Alternative HOV/TOL/educed BT Alternative s to the Alternatives Purpose of this eport EXISTING NOISE ENVIONMENT Background Measuring Noise Levels Typical Sound Levels Factors Affecting Future Traffic Noise Levels Noise Criteria FHWA Noise Criteria FTA Noise Criteria Existing Noise Measurement Program Measurement Program Noise Measurement Sites Existing Noise Levels Vibration Criteria and Existing Levels NOISE IMPACT ASSESSMENT Noise Impact Assessment Methodology FHWA Methodology FTA Methodology Noise Impact Assessment Noise Analysis esults FTA Vibration Impacts April 2007 Page i

6 3.5 Mitigation Measures Evaluation of Alternative Abatement Measures Mitigation of Transit Noise Impacts Mitigation of Vibration Impacts CONSTUCTION NOISE Analysis of Construction Noise Impacts Construction Noise Abatement EFEENCES List of Appendices APPENDIX A - NOISE ASSESSMENT ESULTS APPENDIX B - NOISE WALL ANALYSIS ESULTS APPENDIX C - CONSTUCTION IMPACT ANALYSIS ESULTS List of Figures Figure 1-1. Figure 2-1. Project Location Typical Day-Night Sound Levels Figure 2-2. FHWA and FTA Noise Assessment Monitoring Sites Figure 3-1. Impact Assessment for Sites Analyzed Using FTA Procedures List of Tables Table 2-1. Common Noise Levels and Typical eactions Table 2-2. Table 2-3. Noise Abatement Criteria FTA Guidelines for Land Use Categories and Metrics for Transit Noise Table 2-4. Existing Noise Levels for FHWA Noise Assessment Sites Table 2-5. Existing Noise Levels for BT Station Sites Table 2-6. Existing Noise Levels for Other Supporting Transit Facility Sites Table 2-7. FTA Ground-borne Vibration and Noise Impact Criteria Table 3-1. Approximate Number of Properties with Noise Impacts (FHWA Procedures) Table 4-1. Construction Equipment Noise Emission Levels Page ii April 2007

7 1. INTODUCTION The Federal Highway Administration (FHWA) and Georgia Department of Transportation (GDOT), in cooperation with the Federal Transit Administration (FTA) and Georgia egional Transportation Authority (GTA), propose to make transportation improvements to Interstate 75 (I-75) and I-575 in the Atlanta metropolitan region. The improvements are collectively referred to as the Northwest Corridor Project and could include the construction of high-occupancy vehicle (HOV) lanes, truck-only lanes, bus rapid transit (BT) stations, park-and-ride facilities, a new maintenance base facility, and improved local and express bus service. 1.1 Project Area The Northwest Corridor Project is located northwest of downtown Atlanta, Georgia. I-75 extends to the northwest from downtown Atlanta in Fulton County (see Figure 1-1). Within the study area, I-575 branches from I-75 and extends to the northeast. The highway corridor encompasses the suburban cities of Smyrna, Marietta, Kennesaw, and Acworth and several unincorporated communities in Cobb and Cherokee counties. The area is home to a substantial share of the region s population as well as several business centers, a large regional shopping mall, Dobbins Air Force Base, and numerous major corporations. The main freeway serving the Northwest Corridor is I-75. It is the primary route for commuters traveling to jobs within the region and to downtown Atlanta. As a major north-south route through Georgia, it also serves the transportation needs for regional travel and freight trucking. In downtown Atlanta, I-75 is merged with I-85. Leaving I-85 northbound, I-75 turns to the northwest and proceeds to I-285, which is the beltway around Atlanta. Immediately south of I-285, I-75 has six to seven lanes. North of I-285, the freeway widens to as many as 15 lanes and then narrows again to seven to eight lanes total at the I-575 interchange. I-575 travels northeasterly from Cobb County into Cherokee County, which is comparatively more rural. The I-575 corridor, however, is experiencing rapid urbanization. I-575 has four general-purpose lanes, two in each direction. Transit services in the Northwest Corridor are provided by Cobb Community Transit (CCT) in suburban Cobb County and the Metropolitan Atlanta apid Transit Authority (MATA) in urbanized Fulton County. The existing transit services within the study area consist of local and express bus services. CCT operates 10 local and four express bus routes along I-75 to Midtown and downtown Atlanta. The CCT express bus routes connect with the MATA Arts Center Station in Midtown. 1.2 Purpose and Need Multimodal transportation improvements are proposed for the Northwest Corridor to meet long-term regional transportation needs. Urban development in Cobb and Cherokee counties over the past decades has substantially increased congestion on both I-75 and I-575. Mobility has increasingly become difficult and time consuming for residents, workers, and trucking and distribution companies involved in both local and regional travel. The congestion equally affects single-occupancy vehicles (SOVs), HOVs, buses, and commercial vehicles. In addition, the availability of undeveloped land in the project area and pressures for continued urbanization lead April 2007 Page 1-1

8 Project Location Figure 1-1 Figure 1-1. Project Location Page 1-2 April 2007

9 experts to forecast substantial increases in both population and employment, which would lead to even worse traffic congestion. To address these concerns, the purpose of the Northwest Corridor Project is to address the following needs: Need to reduce congestion Need to improve mobility by reducing travel time and increasing reliability Need to improve access by improving connectivity between regional activity centers Need to improve safety by reducing existing roadway design deficiencies and congestion related crashes Need to reduce vehicle emissions by improving vehicular travel efficiency and increasing the proportion of high-capacity vehicles Project goals and objectives were developed for the Northwest Corridor Project. They were developed based on the transportation needs of the study area and were used to identify alternatives. The goals address project effectiveness, environmental impacts, efficiency and cost-effectiveness, financial feasibility, and equity. The project goals and objectives are listed below. Improve transportation effectiveness of I-75 and I-575 to additional travel and to contribute to the improved performance of the regional system Provide additional transportation choices or options that increase the capacity of I-75 and I-575 Improve the quality of life by improving mobility and minimizing effects to both natural resources and the built environment Improve transportation equity by providing an equitable distribution of benefits and impacts to all populations Provide cost-effective and affordable transportation improvements 1.3 Alternatives The alternatives under consideration include a No- Alternative, a High-Occupancy Vehicle (HOV)/Truck-Only Lane (TOL) Alternative, a HOV/TOL/Transportation Systems Management (TSM) Alternative, a HOV/TOL/Bus apid Transit (BT) Alternative, and a HOV/TOL/ educed BT Alternative. A brief description of these alternatives is provided below. A complete description of the alternatives can be found in the project s Alternatives Analysis/Draft Environmental Impact Statement (see Chapter 2 in that document) No- Alternative The No- Alternative is required by the National Environmental Policy Act (NEPA). It includes all existing highways, transit services, and transit facilities within the Northwest Corridor and remainder of the region. In addition, it includes the planned long-range improvements from the Atlanta egional Commission (AC) Mobility 2030, Volume I: egional Transportation Plan (TP) adopted in December 2004 for the portion outside the Northwest Corridor, except it excludes the planned improvements to I-285. Within the Northwest Corridor, transportation projects funded in the near-term are included as listed in the AC Mobility 2030, Volume II: April 2007 Page 1-3

10 Transportation Improvement Program ( TIP) adopted in February All facilities and services under the No- Alternative also are included under the build alternatives. The No- Alternative serves as a basis for the evaluation of the transportation and environmental impacts of the other four alternatives HOV/TOL Alternative The HOV/TOL Alternative provides for only a minimal expansion of transit service in the corridor in addition to the transit improvements committed in the TIP. This alternative provides the GDOT and the GTA with the ability to advance the HOV/TOL element of the project with only minimal transit improvements. The transit services under the HOV/TOL Alternative are similar to those of the No- Alternative, but with express bus routes operating in HOV lanes and only a minimal increase in the frequency of service HOV/TOL/TSM Alternative The HOV/TOL/TSM Alternative is a lower-cost transit alternative that is comparable to the travel markets served and frequency of service in the HOV/TOL/BT Alternative, but without the higher cost of transit stations on I-75. The HOV/TOL/TSM Alternative includes a major expansion of express bus service operating in the HOV lanes with supporting transit facility improvements, such as park-and-ride lots and bus transfer facilities HOV/TOL/BT Alternative The HOV/TOL/BT Alternative serves the same travel markets as the HOV/TOL/TSM Alternative, but with five BT stations located at proposed HOV interchanges on I-75. The Alternative also has off-vehicle fare collection, multi-level parking structures at four of the BT stations, and commuter-type transit vehicles HOV/TOL/educed BT Alternative The HOV/TOL/educed BT Alternative is very similar to the HOV/TOL/BT Alternative, except that instead of five BT stations, it has only three stations along the I-75 corridor. This alternative is a reduced-cost version of the HOV/TOL/BT Alternative. It is intended as the first phase of implementation of the BT system in the event New Starts funding from the FTA is not available for the five-station HOV/TOL/BT Alternative s to the Alternatives Each of the build alternatives contains options for the design and operation of the HOV/TOL system. There are three design options under consideration: Inside TOL Location of the truck-only lanes to the inside of the roadway on I-75 south of I-575 instead of split to the outside of the roadway. Allgood Flyover eplacement of the HOV interchange at Allgood oad with a flyover between the general-purpose lanes and the inside HOV lanes south of Allgood oad. oswell oad Interchange Alignment Modification to the alignment of the I-75 mainline south of the oswell oad HOV interchange to shift the roadway to the east between South Marietta Parkway and oswell oad to avoid the displacement and relocation of an adjacent church located southeast of the oswell oad interchange. Page 1-4 April 2007

11 In addition to the design options, there are two operational options under consideration: High-Occupancy-Toll (HOT) Lane Allow single-occupancy vehicles (SOV) access to the HOV lanes by paying a toll. The lanes would be managed by pricing to assure that the single-occupancy vehicles (SOVs) using the HOV lanes do not adversely affect the level of service for transit use. Truck-Only-Toll (TOT) Lane equire the trucks using the truck-only lanes to pay a toll. Because all heavy-duty through trucks can be accommodated within the truck-only lanes, the tolls would be applied not only as a lane management tool to assure free-flow conditions, but also as a revenue source to help defray the cost of construction of the lanes. The toll would be set at a level that would not discourage use of the lane to obtain the travel time savings it would provide for trucks operating in the I-75 corridor. The TOT lanes could be mandatory or voluntary for heavy-duty through trucks. 1.4 Purpose of this eport This report presents the results of the traffic and transit noise analysis that was conducted to determine potential noise impacts of the No- Alternative and the build alternatives and associated options. This report also discusses potential mitigation measures to minimize significant adverse impacts from the build alternatives. April 2007 Page 1-5

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13 2. EXISTING NOISE ENVIONMENT Transportation projects have the potential to increase noise levels, which can cause undesirable effects on people, animals, and/or structures. The principal source of noise in the study area is vehicular traffic from automobiles, trucks, and buses. As an existing transportation corridor, most adjacent land uses are exposed to at least moderate noise levels. Whether an increase in noise is objectionable depends on the level relative to existing community noise. Certain land uses, such as hospitals and places of worship, also are sensitive to noise. This chapter presents background information on the characteristics of sound and sound levels, the criteria used by the Federal Highway Administration (FHWA) and Federal Transit Administration (FTA) to measure noise impacts, and the results of noise measurements conducted in the study area at noise sensitive sites. 2.1 Background Measuring Noise Levels Noise is typically defined as unwanted or undesirable sound. The basic parameters of noise that affect humans are (1) intensity or level, (2) frequency content, and (3) variation with time. The first parameter is determined by the level of sound, which is expressed in units of decibels (db). By using this scale, the range of normally encountered sound can be expressed by values between 0 and 120 decibels. On a relative basis, a 3-decibel change in sound level generally represents a barely noticeable change. A 5-decibel change presents a just noticeable change. And a 10-decibel change in sound level would typically be perceived as a doubling in the loudness - a substantial change. The frequency of noise is related to the tone or pitch of the sound, and is expressed in terms of cycles per second called Hertz (Hz). The human ear can detect a wide range of frequencies from about 20 Hz to 17,000 Hz. However, because the sensitivity of human hearing varies with frequency, the A-weighting system is commonly used. Sound levels measured using this weighting system are called A-weighted sound levels, and are expressed in decibel notation as dba. The A-weighted sound level is widely accepted as a proper unit for describing environmental noise. Because environmental noise fluctuates from moment to moment, it is common practice to condense all of this information into a single number, called the equivalent sound level (L eq ). L eq is the level of a steady sound that is equivalent to the sum of individual noise elements over a specified time period (typically 1 hour or 24 hours). Often the L eq values over a 24-hour period are used to calculate cumulative noise exposure, i.e. the Day-Night Sound Level (L dn ). L dn is the A-weighted L eq for a 24-hour period with a 10-decibel penalty imposed on noise that occurs during the nighttime hours (between 10 p.m. and 7 a.m.). This reflects the fact that people are more sensitive to noise during night hours, when interference with sleep is a concern. Many noise surveys have shown that L eq and L dn are well correlated with human annoyance, and therefore these descriptors are widely used for environmental noise impact assessment. April 2007 Page 2-1

14 2.1.2 Typical Sound Levels Figure 2-1 and provide examples of typical noise environments and subjective reaction and criteria in terms of L eq and L dn. While the extremes of L dn s are shown to range from 45 dba in a pristine rural environment to 80 dba in noisy urban environments, L dn is generally found to range between 55 dba and 75 dba in most communities. As shown in the figure, this spans the range between a typical quiet residential environment and the threshold for an unacceptable residential environment. Figure 2-1. Typical Day-Night Sound Levels Source: FTA, Factors Affecting Future Traffic Noise Levels Traffic noise level at a site depends on both site geometry and traffic characteristics (volume, vehicle type, and speed) of proposed roadways near the site. For a straight, at-grade roadway with a steady stream of vehicles, the L eq noise level would decrease when the distance from the roadway to the receptor location increases. Where the area between the roadway and the receptor site is primarily grass or other sound absorptive material, the noise level would drop off at a rate of 4.5 dba per doubling of the distance. A doubling in traffic volume over a given period of time produces a doubling in the sound energy. A doubling in sound energy corresponds to only a 3-dBA increase in noise level, hardly a perceptible change. At locations where traffic volumes and noise levels are already high, a large change in traffic volume would be required to cause a perceptible change in the noise level. Noise levels from trucks are much greater than levels from automobiles. A heavy truck is approximately 47 times (17 dba) noisier than an automobile. Consequently, at a given traffic speed, noise levels are more sensitive to the distance to nearby truck lanes and/or to changes in truck volumes than changes in overall traffic flow. On a roadway, which is carrying a given volume of traffic, road traffic noise level would increase by approximately 5 to 6 dba, as the speed increases from 30 to 45 miles per hour (48 to 72 kilometers per hour), and by another 3 dba, as the speed increases to 55 miles per hour (88 kilometers per hour). Page 2-2 April 2007

15 Table 2-1. Common Noise Levels and Typical eactions Sound Source Noise Level (dba) Apparent Loudness Typical eaction Military jet, Air raid siren times as loud as base Limited amplified speech Amplified rock music times as loud as base Jet takeoff at 500 meters Train horn at 30 meters Freight train at 15 meters 95 Heavy truck at 15 meters Busy city street Loud shout Busy traffic intersection Freeway construction site Freeway traffic at 15 meters oadside traffic Train horn at 500 meters Noisy restaurant Predominantly industrial areas Light car traffic at 15 meters City or commercial areas esidential areas close to industry Noisy office Quiet office Suburban areas with Medium-density transportation Kitchen/bathroom Public library Living/dining/bedroom times as loud as base 90 4 times as loud as base 80 2 times as loud as base Annoying Maximum vocal effort Very annoying, hearing damage (8 hours) 70 Base reference Telephone use difficult 60 1/2 as loud as base reference Intrusive 50 1/4 as loud as base reference 40 1/8 as loud as base reference Quiet 30 1/16 as loud as base reference Beginning of speech interference Very quiet Soft whisper at 5 meters 10 1/64 as loud as base Just audible Threshold of hearing 0 N/A Not audible Note: The minimum difference in noise level noticeable to the human listener is 3 dba. A 10-dBA increase in level appears to double the loudness, while a 10-dBA decrease halves the apparent loudness. Source: Canada Mortgage and Housing Corporation, Noise Criteria Noise criteria are used by FTA and FHWA to measure noise impacts. The basic goals of noise criteria for transportation projects are to minimize the adverse noise impacts on the community and to provide feasible and reasonable noise control where necessary and appropriate. For this project, both agency criteria must be used because the project includes both highway and transit improvements. FTA noise impact criteria was used to assess impacts at sensitive sites near the proposed transit facilities, while FHWA criteria was applied to freeways and major arterial roads where traffic flows relatively freely FHWA Noise Criteria Noise impacts generated by freeway projects are assessed using FHWA noise prediction procedures. FHWA guidelines apply to freeways and major arterial roads where traffic flows relatively freely. The FHWA noise prediction procedures also are applicable for HOV facilities. April 2007 Page 2-3

16 FHWA published its noise abatement criteria in Procedures for Abatement of Highway Traffic Noise and Construction Noise (Federal-Aid Highway Program Manual; Volume 7, Chapter 7, Section 3 (FHWA, 2005). FHWA criteria and noise abatement measures are found in 23 CF 772: FHWA Criteria. They are based on the noisiest hourly L eq value. Table 2-2 provides FHWA s Noise Abatement Criteria (NAC) for different activities. FHWA has defined traffic noise impact as noise levels that approach (within 1 dba) or exceed the NAC. GDOT has adopted FHWA s 1 dba threshold. For example, the approach level is 66 dba for Activity Category B sites. Impact also includes predicted traffic noise levels substantially exceeding existing noise levels. FHWA and GDOT have defined substantially as 10 dba. Table 2-2. Noise Abatement Criteria Activity Category L eq - dba Description of Activity Category A 57 (exterior) 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. B 67 (exterior) Picnic areas, recreation areas, playgrounds, active sports areas, parks, residences, motels, hotels, schools, churches, libraries and hospitals. C 72 (exterior) Developed lands, properties or activities not included in Categories A or B above. D Undeveloped lands. E 52 (interior) esidences, motels, hotels, public meeting rooms, schools, churches, libraries, hospitals and auditoriums. Note: This chart defines noise levels during peak traffic periods at which noise abatement can be considered. Source: FHWA, FTA Noise Criteria Noise criteria promulgated by FTA are defined in the guidance manual Transit Noise and Vibration Impact Assessment, eport FTA-VA (FTA, 2006). FTA guidelines assess noise impacts for various land use categories using different noise metrics (L eq or L dn ). They are presented in Table 2-3. For example, for residential land uses adjoining BT-related facilities, the noise descriptor is L dn. For land uses involving daytime and evening uses and affected by road traffic noise, the noise descriptor is L eq (h). This is the hourly equivalent continuous noise level L eq for the noisiest traffic hour of transit-related activity during which human activities occur at the noise-sensitive locations. The FTA criteria are applicable to the project alternatives, which include such transit components as the transit centers, remote park-and-ride lots, and the bus maintenance facility. While applying these criteria for impact evaluation the project-generated daytime hourly L eq is used as a measure of cumulative noise exposure for non-residential land uses (i.e., those not involving sleep) and the project-generated day-night noise level L dn is used as a measure of cumulative noise exposure for those land uses involving sleep (e.g., residences, hospitals etc.). The impact assessment is based on comparing the future project-generated noise levels with the existing measured noise levels at the sensitive receptor sites. Also, the FTA guidelines are based on relative impact criteria whereby project noise impacts are assessed by comparing the future total hourly L eq or L dn project-generated noise levels against the existing ambient hourly L eq or L dn noise levels. Project impacts are categorized as no impact or impact or severe impact as determined from the allowable increase in cumulative noise exposure over existing ambient noise levels as shown in Appendix A-2. Page 2-4 April 2007

17 Table 2-3. FTA Guidelines for Land Use Categories and Metrics for Transit Noise Land Use Category Noise Metric (dba) Description of Land Use Category 1 Outdoor L eq (h)* Tracts of land where quiet is an essential element in their intended purpose. This category includes lands set aside for serenity and quiet, and such land used as outdoor amphitheaters and concert pavilions, as well as National Historic Landmarks with significant outdoor use. 2 Outdoor L dn esidences and buildings where people normally sleep. This category includes homes, hospitals and hotels where a nighttime sensitivity to noise is assumed to be of utmost importance. 3 Outdoor L eq (h)* Institutional land uses with primary daytime and evening use. This category includes schools, libraries, and churches where it is important to avoid interference with such activities as speech, meditation and concentration on reading material. * Leq for the noisiest hour of transit-related activity during hours of noise sensitivity. Source: FTA, Existing Noise Measurement Program Measurement Program Existing noise levels within the study area were assessed based on noise measurements taken at noise-sensitive sites. The noise measurements were conducted during March and April 2005 and February and March Noise Measurement Sites Considering both FHWA and FTA noise criteria must be used to assess potential impacts, the selection of noise sites for baseline measurements must be selected consistent with the different agencies criteria. Basically, noise measurement sites using the FHWA criteria are scattered along the entire length of the project corridor, while the noise measurement sites using the FTA criteria are clustered around the proposed sites of new transit facilities, particularly the BT stations and park-and-ride lots. The noise measurement sites using both FHWA and FTA noise criteria are shown in Figure 2-2. These sites consist of residential dwellings, institutional uses, churches, hotels, recreational areas, and a sports center and were considered representative of typical conditions within the study area. The sites for noise monitoring were selected based on an extensive review of proposed transportation improvements. The criteria for site selection included land use, existing ambient noise, number of sensitive receivers in the area, and the site s potential sensitivity to changes in noise levels. Noise measurements for each site were performed in accordance with procedures described in Sound Procedures for Measuring Highway Noise Final eport (FHWA, 1981). The measurements were taken using two calibrated sound level meters: (1) Bruel and Kjaer (B&K) noise measuring equipment and (2) a Quest 2900/Type II sound level meter. All measurements were performed under acceptable climatic and street surface conditions (i.e., dry road surface and wind speeds less than 20 km/hr). Short-term L eq measurements during the morning, midday, and evening were taken to best characterize the daily noise exposure at a site and the area around it. This information was used to estimate the L dn at residential sites or at other sites with similar land uses where nighttime April 2007 Page 2-5

18 FHWA and FTA Noise Assessment Monitoring Sites Figure 2-2 Figure 2-2. FHWA and FTA Noise Assessment Monitoring Sites Page 2-6 April 2007

19 sensitivity is an important factor. These estimated L dn noise levels were used for the FTA noise impact assessment of transit facilities Existing Noise Levels The principal source of noise in the study corridor is from motor vehicles moving along I-75 and I-575 and the access ramps to these freeways. Adjacent residential communities and commercial areas are currently exposed to moderate levels of traffic noise Existing Noise Levels at FHWA Noise Assessment Sites Noise measurements using the FHWA criteria were conducted at 36 sites adjacent to I-75 and I-575. The measurements were taken during the midday period when noise levels are highest with traffic free flowing and not congested. These L eq noise level measurements are summarized in Table 2-4. Noise levels at the 36 sites on I-75 and I-575 ranged from an hourly L eq of 54 dba at site M34 on I-575 to an hourly L eq of 83 dba at site M6B on I-75. The 36 sites consisted of 34 residential sites, one church, and one hotel. Sites M6B and M8B are both in front of existing noise walls facing the freeway and are not considered sensitive receptors. Noise levels at 12 of these sites approached or exceeded the FHWA NAC. These sites were FHWA Category "B" sites. On I-75 these included: M3, M6A, M7, M8A, M10, M16, M17, M19, M20, M21, and M22. On I-575, there was only one such site, M32. Table 2-4. Existing Noise Levels for FHWA Noise Assessment Sites eceptor ID eceptor Address Land Use I-75/M1 I-75/M2 I-75/M3 Marriott Hotel North of Windy idge Pkwy 2825 Belmont Place Apartment Gardens Windy Hill d Barrington Mill Apartment Terrell Mill d I-75/M4 Lincoln Hills Apartment Homes North of Terrell Mill d I-75/M5 Highland Park Apartment Homes North of Delk d I-75/M6A 818 Forest idge Dr (behind existing noise wall) North of Delk d I-75/M6B I-75 shoulder NB direction (in front of existing noise wall) I-75/M7 The Crossings at Wood Station Apartment Homes Franklin d I-75/M8A 946 Forest idge Dr (behind existing noise wall) North of Delk d I-75/M8B I-75 shoulder NB direction (in front of existing noise wall) I-75/M9 Crestridge Dr North of South Marietta Pkwy Distance to the Median (Feet) Date Time Hotel 299 to I-285 entrance ramp and 474 to I-75 esidential 569 to the on-ramp and 710 to I-75 L eq (1h) (dba) 4/12/05 1:25 PM 65 4/12/05 3:15 PM 62 esidential 507 4/19/05 1:57 PM 68 esidential 358 4/13/05 12:45 PM 60 esidential 537 4/13/05 11:57 AM 53 esidential 225 4/21/05 11:58 AM /21/05 12:37 PM 83 esidential 325 4/21/05 1:21 PM 70 esidential 201 4/12/05 10:20 AM /12/05 10:48 AM 84 esidential 463 to the on-ramp and 763 to I-75 3/31/05 3:02 PM 61 April 2007 Page 2-7

20 Table 2-4. Existing Noise Levels for FHWA Noise Assessment Sites (continued) eceptor ID eceptor Address Land Use Distance to the Median (Feet) Date Time I-75/M Banberry d Franklin d esidential 267 3/30/05 2:54 PM 69 I-75/M Old Bee Tree Cir South of Gresham d L eq (1h) (dba) esidential 411 3/30/05 2:10 PM 64 I-75/M12 Alpine Way North of N. Marietta Pkwy esidential 532 3/30/05 11:45 AM 59 I-75/M Bankston d North of N. Marietta Pkwy I-75/M14 Iglesia Congregacion Cristiana Allgood d I-75/M15 Park Lane/Dickson d North of Canton d Conn/Hwy 5 I-75/M Lancaster Drive South of the junction of I-75 and I-575 I-75/M Shiloh Valley Trl North of the junction of I-75 and I-575 I-75/M18 Greenhouse Apartment Complex South of Frey d I-75/M19 Apartment Complex (KSU Housing) Idlewood Ave I-75/M20 Villas at Kennesaw Apartment Homes George Busbee Pkwy I-75/M21 Somerset at Shiloh Apartment Homes North of Wade Green d I-75/M Hamby Cove Dr North of Hickory Grove d I-75/M Howell Farms North of Hickory Grove d esidential 325 3/30/05 1:18 PM 63 Church /29/05 3:37 PM 59 esidential esidential 392 to the onramp and 965 to I to the SB I-575 ramp and 455 to I-75 3/29/05 2:24 PM 64 4/14/05 10:11 AM 69 esidential 338 4/12/05 2:41 PM 71 esidential 434 3/29/05 1:23 PM 64 esidential 323 3/29/05 12:42 PM 66 esidential esidential esidential esidential 220 to the offramp and 356 to I to 1-75 SB and 340 to I to 1-75 NB and 530 to I to 1-75 SB and 590 to I-75 3/29/05 11:20 AM 67 2/28/06 2:38 PM 67 2/28/06 1:20 PM 69 2/28/06 12:27 PM 64 I-575/M Nottley Dr South of Barrett Pkwy esidential 328 3/30/05 2:15 PM 57 I-575/M Hidden Forest Dr South of Big Shanty d esidential 344 3/30/05 1:25 PM 63 I-575/M Etheridge Dr North of Chastain d esidential 243 3/30/05 12:05 PM 63 I-575/M Heck d North of Bells Ferry d esidential 454 to on-ramp and 809 to I-575 I-575/M Oak Ferry Dr North of Bells Ferry d I-575/M Nesbin Dr North of Hawkins Store d 3/29/05 2:35 PM 65 esidential 228 3/31/05 3:53 PM 64 esidential 255 3/30/05 11:30 AM 59 I-575/M Castleair Dr North of Shallowford d esidential 277 3/30/05 10:50 AM 65 I-575/M Tanglewood Dr North of E. Alabama d/s-92 I-575/M32 21 Coffee Cir (Mobile Homes) North of Dupree d I-575/M Dream Catcher d South of ope Mill d esidential 469 to off-ramp and 582 to I-575 3/29/05 2:10 PM 63 esidential 188 4/13/05 10:01 AM 73 esidential 301 3/29/05 11:30 AM 61 I-575/M ope Mill d esidential 487 3/30/05 10:05 AM 54 Note: Noise measurements were recorded for 15-minute duration per reading. Page 2-8 April 2007

21 Existing Noise Levels at FTA Noise Assessment Sites Noise measurements using the FTA criteria were conducted at sites near the proposed BT stations along I-75 and at sites near the proposed locations of the transit centers, remote parkand-ride lots, and the bus maintenance facility. Table 2-5 presents measured L eq noise levels and estimated L dn noise levels for sites in the vicinity of the proposed BT station locations. The estimated L dn levels range from 62 L dn at site B2 to 75 L dn at site B3. Both of these sites are Category 2 residential land uses. Table 2-6 presents measured L eq noise levels and estimated L dn noise levels for sites in the vicinity of other supporting transit facilities. The L dn levels range from a low of 54 L dn at site T5 to a high of 74 L dn at site T8. Table 2-5. Existing Noise Levels for BT Station Sites ecept or ID eceptor Address Land Use BT B1 Proposed Arts Center Cobb Institutional Galleria Pkwy BT B2 Walton ivers Apartment Homes South of Akers Mill d BT B3 Autumn View Apartment Homes North of Delk d BT B Halsey d (Mobile Homes) South of Gresham d BT B Eastview Drive (Mobile Homes) South of Gresham d BT B6 Ice Forum George Busbee Pkwy esidential esidential 214 esidential 665 esidential 333 Sport Center (Indoor Use) Note: Noise measurements were recorded for 15-minute duration per reading. Distance to I-75 Median (Feet) Date Time L eq (1h) (dba) 122 to the SB onramp 4/13/05 2:01 PM 58 and 303 to I-75 4/15/05 12:43 AM to I-75 and 3/2/06 9:54 AM to Cumberland Blvd 3/8/06 1:30 AM 55 4/21/05 1:57 PM 72 4/15/05 2:29 AM 68 3/1/06 9:44 AM 58 3/2/06 12:15 AM 57 4/14/05 3:29 PM 67 4/20/05 1:50 AM 61 1,293 4/14/05 1:52 PM 56 4/21/05 2:23 AM 59 Estimated L dn Vibration Criteria and Existing Levels Vibration impacts generated by transit portion of the project are assessed by using FTA vibration prediction procedures. FTA guidelines apply to transit vehicles operating near BT stations and near other supporting transit facilities. FTA published its vibration impact criteria in the FTA Manual Transit Noise and Vibration Impact Assessment (FTA, 2006) to assess vibration impacts from transit operations. The criteria are based on the maximum vibration level in decibels (vibration decibels or VdB) generated by a single event. The FTA criteria for acceptable ground vibration are expressed in terms of root mean square (rms) vibration velocity and the impact threshold levels are specified for three land use categories. Table 2-7 provides FTA s ground-borne vibration criteria for different land uses. Following the guidelines in the FTA Transit Noise and Vibration Impact Assessment Manual, no existing vibration measurements were taken because the major sources of vibration in the study area are automobiles, trucks, and buses. April 2007 Page 2-9

22 Table 2-6. Existing Noise Levels for Other Supporting Transit Facility Sites eceptor ID eceptor Address Land Use Date Time L eq (1h) (dba) T1 West Peachtree d Park ecreational 6/30/05 5:06 PM 62 Area 7/01/05 1:00 AM 59 T2 First Presbyterian Church of Church 6/30/05 4:31 PM 59 Atlanta 16th St 7/01/05 12:30 AM 54 T3 Best Western Granada Suite Hotel Hotel 6/30/05 3:34 PM 70 West Peachtree d 7/01/05 12:00 AM 64 T4 Embassy Suite Hotel Akers Mill Hotel 7/14/05 12:05 PM 60 d 7/01/05 2:00 AM 46 T5 Post Crest Apartment Homes esidential 3/1/06 2:19 PM 50 Cumberland Mall 3/2/06 2:10 AM 47 T Hicks d esidential 6/29/05 3:15 PM 65 6/30/05 2:17 AM 56 T7 Heritage Hills Golf Center esidential 3/2/06 3:46 PM 62 S 5 / East West Connector 3/8/06 12:40 AM 50 T8 260 Dorothy Dr Austell d esidential 3/1/06 4:27 PM 74 3/2/06 3:30 AM 65 T9 Laurel Apartments Laurel Valley esidential 6/29/05 2:10 PM 58 Dr 6/30/05 1:30 AM 51 T10 Laurel Valley Apartment Homes esidential 3/1/06 12:11 PM 61 North of Terrell Mill d 3/2/06 1:35 AM 53 T11 Highland Trace Apartment Homes esidential 3/1/06 11:10 AM 65 North of Delk d 3/2/06 12:55 AM 63 T S. Marietta Pkwy West of esidential 3/1/06 3:25 PM 70 South Cobb Pkwy 3/2/06 2:54 AM 59 T Woodlawn Drive Johnson esidential 3/2/06 11:00 AM 65 Ferry d 3/9/06 8:52 AM 66 3/9/06 11:07 AM 64 3/14/06 11:38 PM 53 T New South Dr Canton d / esidential 3/2/06 12:15 PM 55 Piedmont d 3/8/06 3:50 AM 44 T /2818 Colleton Dr Canton esidential 3/7/06 5:40 PM 50 d / Piedmont d 3/9/06 10:01 AM 52 3/8/06 3:22 AM 50 T16 Children s Hospital George Hospital 2/28/06 3:32 PM 66 Busbee Pkwy 3/8/06 4:30 AM 61 T Wetherbyrne d esidential 6/28/05 11:20 AM 56 Wetherbyrne Woods 6/29/05 12:42 AM 49 T18 Lake Acworth Dr S-92 Hotel 7/14/05 7:38 AM 68 6/29/05 12:02 AM 61 Note: Noise measurements were recorded for a 15-minute duration per reading. Estimated L dn Page 2-10 April 2007

23 Table 2-7. FTA Ground-borne Vibration and Noise Impact Criteria 1 Land Use Category Category 1: ings where low ambient vibration is essential for interior operations Category 2: esidences and buildings where people normally sleep Category 3: Institutional land uses with primarily daytime use Vibration Velocity Impact Levels for Frequent Events 2 Vibration Velocity Impact Levels for Infrequent Events 3 Noise Impact Levels for Frequent Events 2 Noise Impact Levels for Infrequent Events 3 65 VdB 4 65 VdB 4 NA 5 NA 5 72 VdB 80 VdB 35 dba 43 dba 75 VdB 83 VdB 40 dba 48 dba Notes: 1. Vibration Levels Expressed in VdB are 1 micro inch/sec and noise levels in dba. 2. Frequent Events is defined as more than 70 vibrations per day. Most rapid transit projects fall into this category. 3. Infrequent Events is defined as fewer than 70 vibration events per day. This category includes most commuter rail systems. 4. This criterion limit is based on levels that are acceptable for most moderately sensitive equipment such as optical microscope. 5. Ground-borne noise criteria are generally applicable to vibration generated by wheel-rail interaction in rail projects. April 2007 Page 2-11

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25 3. NOISE IMPACT ASSESSMENT This chapter presents the results of the assessment that was conducted to determine potential noise impacts of the No- Alternative and the build alternatives and associated options. This chapter also discusses potential mitigation measures to minimize significant adverse impacts of the alternatives. 3.1 Noise Impact Assessment Methodology FHWA Methodology The proposed project requires improvements to the highway and the construction of additional travel lanes to an existing highway and therefore, it would be classified as a Type I project under the FHWA regulations. For Type I projects, the consideration of noise impact and potential mitigation is mandatory during the project development process. The traffic noise impacts for the Northwest I-75/I-575 Corridor Project have been assessed in accordance with FHWA procedures published in 23 CF 772 for determining when traffic noise impacts will occur (FHWA, 2005). GDOT uses FHWA procedures for impact assessment and abatement analysis. Further elaboration of these procedures is provided here. These procedures involve performing the following steps: 1. Identify existing land uses and activities, developed lands, and undeveloped lands for which development is planned, designed, and programmed that may be affected by traffic-related noise in the study area; 2. Determine existing year 2005 measured or modeled noise levels in the study area; 3. Predict future design year 2030 noise levels, which would occur for the No- Alternative and the build alternatives. The future noise levels were predicted using the FHWA Traffic Noise Model (TNM 2.5); 4. Compare future noise levels with existing noise levels and with FHWA Noise Abatement Criteria (NAC) to identify traffic noise impacts and the need for abatement; 5. Identify where noise impacts would be anticipated; 6. Identify which noise abatement must be considered; and 7. Investigate various types of noise abatement measures that might be used to reduce or eliminate traffic noise impacts. FHWA regulations identify dba noise levels on the basis of the L eq (1 hour) noise descriptor and NAC levels at which noise abatement must be considered. Under these regulations, the proposed study would be considered to cause traffic noise impacts if the future noise levels approached, or exceeded the NAC for the appropriate activity category. The NAC apply to areas with having regular human use and where lowered noise levels are desired. They do not apply to the entire tract of land on which the activity is based, but only to that portion where the activity takes place. Also, FHWA regulations indicate that, Noise impacts occur when the predicted traffic noise levels approach or exceed the NAC levels, or when the predicted design-year traffic noise levels substantially exceed the existing noise levels, even though the predicted noise levels may not exceed the NAC. To assess the future potential noise effects of the build alternatives, it is necessary to include noise from increased road traffic near sensitive receptors where existing noise levels were April 2007 Page 3-1

26 monitored. The methodology for predicting future traffic noise levels used the FHWA traffic noise model TNM2.5. The TNM incorporates algorithms for sound emissions and propagation that are based on well-established theory and accepted international standards. The traffic data and engineering drawings developed for the Alternatives Analysis/Draft Environmental Impact Statement (AA/DEIS) were used as input to the TNM. In general, sound propagation over acoustically soft ground (such as lawn) was assumed throughout the study area. One existing noise barrier was identified during the field survey of the study area and it was modeled for existing conditions and for the future No- Alternative. However, the existing noise barrier was not modeled for the build alternatives considered in this document because it would be removed FTA Methodology The FTA criteria are applicable to the build alternatives that include such transit components as the transit centers, remote park-and-ride lots, and the bus maintenance and storage facility (see. The noise impacts for the transit portion of the Northwest I-75/I-575 Corridor Project have been assessed in accordance with FTA procedures published in the FTA Manual. While applying these criteria for impact evaluation the project-generated daytime hourly L eq is used as a measure of cumulative noise exposure for non-residential land uses (i.e., those not involving sleep) and the project-generated day-night noise level L dn is used as a measure of cumulative noise exposure for those land uses involving sleep (e.g., residences, hospitals etc.). The impact assessment is based on comparing the future project-generated noise levels with the existing measured noise levels at the sensitive receptor sites (Appendices A-7 through A-11). To assess the potential noise effects of the transit alternatives, it is necessary to include noise from future transit activity near sensitive receptors that were selected for the noise analysis where existing noise levels were monitored. The methodology for predicting future transit noise levels use the FTA noise model, which is available in spread sheet form. The input to the spreadsheet includes the FTA defined category of land use, number and speeds of BT vehicles, distance to the receptor sites, and the type of intervening ground surface between the transit noise source and the receptor. Noise from park-and-ride lots and from parking garages and maintenance facilities were assessed based on the number of vehicles accessing these facilities and by following the FTA equations for calculating noise levels from stationary and mobile sources near the sensitive receptor sites. 3.2 Noise Impact Assessment To facilitate a comparison of the existing, the No- Alternative, and the build alternatives, predicted noise levels for the FHWA sites under both alternatives and project options were calculated using the FHWA noise prediction computer model (TNM2.5). Computer modeling accounts for such factors as ground absorption, roadway geometry, receptor distance, vehicle volumes, operating speeds. The types of vehicles modeled were autos, medium trucks (vehicles with two axles/six tires), heavy trucks (three axles or more), buses, and motorcycles. The speeds that were used in the noise model were 65 mph for highway, 55 mph for on-ramps and off-ramps, and 45 mph for cross streets. Because the noise analysis is derived from the traffic data, the analysis incorporates proposed traffic improvements in the project area. As such, the noise impact analysis addresses direct, indirect, as well as cumulative effects of the proposed project. For the FTA sites, the analysis procedure consisted of comparing the project-generated noise level with the measured existing noise levels and determines the impacts based on the FTA criteria as presented in the FTA Manual (FTA, 2006). Page 3-2 April 2007

27 Impact Assessment for Sties Analyzed Using FTA Procedures Figure 3-1 Figure 3-1. Impact Assessment for Sites Analyzed Using FTA Procedures April 2007 Page 3-3

28 Key steps in the traffic and transit noise impact assessment requires the following three comparisons: The noise levels under the existing conditions must be compared to those under the build conditions. This comparison shows the noise level changes that can be expected to occur between the present time and the design year. For traffic noise assessment the noise levels under the design year No- Alternative must be compared to those under the design year for the build alternatives. This comparison shows how much of the change in noise levels can actually be attributed to the proposed project. The noise levels under the build alternatives must be compared to the applicable FHWA NAC for road traffic noise assessment. The noise levels under the build conditions must be compared to the existing measured noise level as required by the FTA guidelines for the BT and the transit portion of the alternatives. These comparisons will determine the acceptability of noise levels under present as well as future conditions for the sensitive land uses. Noise impacts from the future I-75/I-575 traffic were identified at FHWA Category B and Category C land uses by using GDOT and FHWA procedures. Noise impacts from transit operations were identified at FTA land use Categories 2 and 3 by using the FTA guidelines. Where impacts were identified, GDOT and FTA guidelines were used to evaluate and recommend feasible and reasonable noise mitigation measures. Based on a corridor wide inspection of aerial photographs and US Geological Survey maps, and from overlay of future estimated traffic noise contours, an approximate count was made of the total number of residences (FHWA Category B sites) and developed properties other than residences (FHWA Category C sites) that would experience traffic noise impacts for the proposed Northwest I-75/I-575 Corridor improvements. In total, noise levels were estimated at an additional 314 Category B and 40 Category C sites, and adding up to a total of 354 receptor sites. This information was used to plot the future estimated 66 dba and 71 dba traffic noise contours for the entire corridor. 3.3 Noise Analysis esults The results of the noise impact analysis based on the FHWA and FTA procedures are presented in detail in Appendix A. Two receptor sites (42 and 52) recorded a substantial increase (more than 10 dba) in future noise level over the existing noise level. The same two receptor sites registered a substantial increase in the build alternative noise levels over the No- Alternative noise level. The results presented in Table 3-1 identify the total number of properties that would be potentially affected as a result of the build alternatives. The number of affected properties was determined by counting the number of properties that lie within the estimated 66 dba and 71 dba noise contours. It is seen from this table that the worst-case alternative (HOV/TOL/BT Alternative) would affect approximately 686 Category B properties and 55 Category C properties. The approximate number of properties that would be affected under the oswell oad Interchange is 687 Category B sites and 54 Category C sites, and under the Allgood Flyover would affect 685 Category B sites and 55 Category C sites. Similar results were obtained for the two options under the other build alternatives. The approximate number of Category B properties that would be affected in the I-575 corridor is 335. For the I-575 corridor, only one Category C site was identified to experience a substantial increase in noise. Page 3-4 April 2007