MAY 4, 2011 Noise Barrier Presentation NE Quadrant Smith Avenue, Cherry Hill Circle 1
Introductions Agenda Overview of Interchange Project Overview of noise barrier process Fundamentals of sound & proposed noise barrier Discussion and voting 2
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Existing Methuen Rotary (Exit 46; 2004) Proposed Partial Cloverleaf at Exit 46; approx. 2016 4
I-93 SB I-93 NB 34 30 26 27 40 Cherry Hill Cir. 26 24 20 16 Rte. 110/113 5
Sound Fundamentals Pressure Wave Travels in a Straight Line Threshold of Hearing 20 MicroPascals = 0 Decibels Hearing Range Spans 0 to 110 db A-Weighted Decibels 6
Sound Levels in Decibels The A-weighting Curve (dba) approximates how people hear sound 7
Sound Level (dba) Sound Study Uses the Leq Energy-Average Sound Level Time 8
Common Sound Levels Jacobs Engineering Group, Inc. 9
Sound Attenuation Waves spread out with distance Waves are reflected by terrain and structures Waves are absorbed and blocked by sound barrier walls 10
Highway Sounds 11
Distance Attenuation -3 dba for every doubling of distance from a roadway Travel lane sound source 3 6 9 12 Distance (feet) 12
Sound Barrier Walls An effective sound wall blocks the line of sight to most sections of a roadway 13
Acoustic Study Process Measurements Over 8 Days October 2008 Calculate Future Sound Levels Determine Traffic Noise Impacts Design Noise Mitigation 14
Noise Study Assumptions Analyze the Noisiest Traffic Hour (NTH) L eq for 2 p.m. to 3 p.m. weekday Dry roads, calm winds No leaves on trees 15
Sound Fundamentals Change in Sound Levels 3 dba Just Audible 5 dba Noticeable 10 dba Double Loudness 16
Study Area & Sound Monitoring Locations 27 Smith Ave. Valley Office Park 1 Heather Dr. 447 Lowell St. 16 Allen St. 4 Noyes St. 17
Acoustic Study FHWA Traffic Noise Model (TNM) Study Alternatives 2009 Existing Conditions 2030 No-Build 2030 Build Improvements Sound levels predicted at homes within 500 feet of project roadways 18
Sound Levels At Homes Within 500 of I-93, Routes 110/113 Study Condition 1-hour L eq (dba) 2009 Existing Conditions 59 74 2030 No-Build 61 75 2030 Build Improvements 62 75 19
Typical Noise Barrier 20
MassDOT Noise Abatement Policy Type I Noise barriers built as part of new highway construction Type II Noise barriers built on existing highways (no new highway construction) 21
MassDOT and FHWA Define a Traffic Noise Impact as a Sound Level at a Residence 66 + dba, or Increase of 10 dba 22
MassDOT Noise Abatement Policy Feasibility of Noise Barrier Goal Noise barrier to achieve a 10 dba reduction for first row of residences Minimum Requirement - Achieve a 7 dba reduction for first row of residences Issues to consider Include: Driveways Cross Streets Wetlands 23
MassDOT Noise Abatement Policy Reasonableness of Noise Barrier Cost Effectiveness Index (CEI) <= $2,700 CEI = Barrier cost $ 1 / # homes protected / insertion loss in dba Example CEI = $2,696 = $496,000 / 23 Homes protected / 8.0 dba 1 Using an assumed cost of $16/SF. Actual costs are higher at $65/SF. 24
Smith Ave./Cherry Hill Circle Noise Barrier Design Average Noise Reduction 23 Homes 8.0 dba Noise Barrier Dimensions Length 1,240 feet Height 25 feet above grade 25
Smith Avenue/Cherry Hill Circle Existing Sound Levels (2009) 64 to 74 dba Future Sound Levels No Barrier (2030) 65 to 75 dba Future Sound Levels with Barrier (2030) 59 to 68 dba 26
Sound Levels in 2030 Residence No Barrier With Barrier Reduction (dba) (dba) (dba) 3 Smith Avenue 64.7 62.3 2.4 5 Smith Avenue 64.6 61.6 3.0 7 Smith Avenue 65 61.4 3.6 8 Smith Avenue 65.1 61.6 3.5 9 Smith Avenue 65.5 61.3 4.2 11 Smith Avenue 66.4 61.2 5.2 12 Smith Avenue 66 61.5 4.5 13 Smith Avenue 68 61.2 6.8 15 Smith Avenue 69.2 60.8 8.4 16 Smith Avenue 66.7 61.3 5.4 19 Smith Avenue 71.2 60.3 10.9 20 Smith Avenue 67.8 60.8 7.0 24 Smith Avenue 68.1 59.8 8.3 26 Smith Avenue 70.2 59.5 10.7 27 Smith Avenue 74.8 59.4 15.4 27
Sound Levels in 2030 Residence No Barrier With Barrier Reduction (dba) (dba) (dba) 1 Cherry Hill Circle 66.6 62.3 4.3 2 Cherry Hill Circle 65.4 61.4 4.0 5 Cherry Hill Circle 67.9 62.2 5.7 6 Cherry Hill Circle 66.4 61.6 4.8 9 Cherry Hill Circle 69.4 62.6 6.8 10 Cherry Hill Circle 67.7 61.4 6.3 14 Cherry Hill Circle 69 61.3 7.7 15 Cherry Hill Circle 71.1 63.1 8.0 17 Cherry Hill Circle 70.9 65.0 5.9 18 Cherry Hill Circle 70.5 61.3 9.2 21 Cherry Hill Circle 70.9 66.5 4.4 22 Cherry Hill Circle 72.2 61.6 10.6 26 Cherry Hill Circle 74.2 62.3 11.9 30 Cherry Hill Circle 73.8 63.1 10.7 34 Cherry Hill Circle 73.3 65.2 8.1 40 Cherry Hill Circle 73.1 68.0 5.1 66 Forest Street 70.3 67.6 2.7 84 Forest Street 72.7 70.9 1.8 88 Forest Street 74.9 74.5 0.4 28
Methuen Noise Barrier Context I-93 NB Cherry Hill Cir. Smith Ave. 29
Barrier Smith Ave./Cherry Hill Cir. 1 2 3 4 Proposed Noise Barrier 30
Existing View #1 Between 34 and 40 Cherry Hill Circle 31
Existing View #2 From Smith Avenue cul-de-sac 32
Barrier Appearance #2 View from Smith Avenue cul-de-sac Preliminary Artist s Rendering 33
Barrier Appearance #2 View from Smith Avenue cul-de-sac Existing View Preliminary Artist s Rendering View with Proposed Noise Barrier 34
Existing View #3 From 26 Smith Avenue 35
Barrier Appearance #3 View from 26 Smith Avenue Preliminary Artist s Rendering 36
Barrier Appearance #3 View from 26 Smith Avenue Preliminary Artist s Rendering Existing View View with Proposed Noise Barrier 37
Existing View #4 From 12 Smith Avenue 38
Noise Barrier Design Schedule First Abutter Meeting today! Second Abutter Meeting to discuss noise barrier design and landscaping Fall 2011 39
Questions/Voting 40