Why is the project needed?
Many residents are concerned with noise in our heavily traveled urban areas. People want solutions that will reduce traffic noise in their neighborhoods. WSDOT identified highway traffic noise along I-5, between 5th Avenue NE and NE 92nd Street, as a high priority for noise mitigation.
We identified this as a priority because when we built I-5 in the 1960s, noise was less of a concern, largely because there was less traffic. Since then, noise levels increased significantly as traffic grew.
What is the project?
WSDOT is built three noise walls on the west side of I-5 (Stage 1) between 5th Avenue NE and NE 92nd Street. WSDOT is continuing the design of one noise wall (Wall 1-North) on the east side of I-5 (Stage 2) between NE 85th Street and NE 92nd Street.
Why are there two stages of this project?
In 2006, we held a meeting with neighbors to discuss the potential schedule and location conflicts with Sound Transit’s North Link light rail project. With support from legislators and the Maple Leaf community in early 2007, we postponed the design and construction (pdf 31 kb) of the proposed noise wall in this area, pending the results of a 2007 ballot measure to fund the light rail project. While this portion of the project was on hold, we completed design for the three walls on the west side of I-5 and split the project into two stages. When the funding for proposed light rail line was rejected by voters in November 2007, we moved forward with the design of the proposed noise wall (Wall 1) in the Maple Leaf neighborhood.
What is the project timeline?
- 2005-2007: Complete planning phase.
- 2007-2008: Complete noise wall designs and community polling process.
- July 2008- June 2009: Construction of west side noise walls.
- 2005-2007: Planning phase. With support from legislators and the Maple Leaf community in early 2007, WSDOT postponed the design and construction of the proposed noise wall on the east side of I-5.
- 2008-2009: Design east side noise wall and conduct community poll with property owners.
- 2009-2010: Begin construction of Wall 1-North in summer/fall 2009.
Which neighborhoods will be affected by the project?
Neighborhoods affected by this project include Maple Leaf, Licton Springs, and north Green Lake.
What is the project budget?
WSDOT received $14.7 million in funding from the Legislature as part of the 2005 Gas Tax to design to build up to four noise walls in the area between 5th Ave NE and NE 92nd Street. This money will be used to design and construct three noise walls on the west side of I-5 (Stage 1) and one noise wall on the east side of I-5 (Stage 2).
Why were there initially two segments of Wall 1?
In the preliminary design stage, Wall 1 included two segments: Wall 1-North, between NE 92nd Street and NE 85th Street, and Wall 1-South, between NE 85th Street and NE 80th Street. Wall 1 was split into two segments to allow property owners to participate in separate polls for each segment. Property owners were able to consider impacts to views and other neighborhood features independently.
Why was Wall 1-South removed from the project?
In July 2008, we facilitated a community poll with property owners who were eligible to participate. Separate polls were conducted for Wall 1-North and Wall 1-South. For Wall 1-South, we received ballots from 75 percent of eligible property owners; 41 percent of the weighted total indicated support for Wall 1-South. Among returned ballots from property owners living closest to the proposed noise wall, 75 percent opposed the further design and construction of Wall 1-South. The results of the community poll, along with other feedback that we received from Wall 1-South neighbors, did not signify support for the wall. As a result, we removed Wall 1-South from the project.
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Stage 2: Design and Landscaping
What will Wall 1-North look like?
We are using a newly available non-concrete noise wall product called Carsonite AcoustaShield (pdf 103 kb) rather than typical concrete for this noise wall. The Carsonite planks are made of a composite that is strengthened with fiberglass and filled with ground-up tire rubber. The narrow interlocking planks will be installed vertically like fence slats.
What landscaping will be planted on the neighborhood side of Wall 1-North?
WSDOT landscape architects have developed three different landscaping concepts for the neighborhood side of Wall 1-North to provide choices to the community. Some of the differences between the three concepts include the color variation, the size and types of the plants and the maintenance requirements. Landscaping concepts include:
Who will maintain the landscaping?
As part of the project, our crews will maintain the landscaping for three years to help establish new plants. Crews will weed new plants, water new plants and replace plants if they do not survive. After three years, continued care of the landscaping will require community effort to ensure ongoing success. While the plants themselves should be self-sustaining after the first three years, occasional weeding will be needed to keep up the landscaping.
How will the noise wall alter the landscaping near Wall 1-North?
Our goal is to retain as many trees and plants currently near the noise wall location as possible. To accommodate the equipment needed for construction, we will likely need to remove some trees closest to the noise wall location. Trees that are on the residential side of the noise wall that have branches overhanging into our right of way may need to be trimmed to accommodate construction. When the project is complete, we will reestablish vegetation lost during construction. Any new plantings on the highway-side of the noise wall will be consistent with the existing landscaping along this stretch of I-5.
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Will Sound Transit’s North Link light rail project impact the noise wall?
In November 2008, voters approved the Sound Transit 2 Mass Transit Expansion proposal which includes funding to extend light rail to Lynnwood. North Link light rail will be located in the same area as Stage 2 of our noise wall project. We have been aware of this potential conflict from the beginning of the project and have been coordinating with Sound Transit to minimize impacts to the noise wall project. We will continue to coordinate with Sound Transit as they begin final design and construction of North Link.
What will happen to the noise wall and landscaping when North Link light rail is constructed?
Sound Transit may need to remove the noise wall and associated landscaping in this area to construct the North Link light rail. As Sound Transit continues to develop their plans and construction schedule, we will work with them to determine what impacts this could have to the noise wall.
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What is a noise wall?
A noise wall is a barrier that can be constructed from a variety of materials. WSDOT typically uses concrete for noise walls. These noise walls vary in height and appearance depending on the location of their installation. For Stage 2 of this project, we are considering using lightweight materials rather than traditional concrete.
How does a noise wall work?
Noise walls reduce highway traffic noise from entering adjacent neighborhoods by reflecting or diffusing the noise. To achieve the maximum noise reduction possible, a noise wall must be tall enough and long enough to block the view of a highway from your home.
How does WSDOT decide where to build noise walls?
WSDOT considers constructing noise walls for two scenarios:
- Scenario 1: WSDOT considers constructing noise walls in neighborhoods that will experience an increase in traffic noise after the completion of a state highway project, such as a new road widening project. Design and construction of these walls are added to the scope and budget of the highway project to reduce the overall effect of increased traffic noise on the surrounding community.
- Scenario 2: Noise walls are also considered for neighborhoods that were developed prior to May 14, 1976 that are adjacent to major freeways currently experiencing a high level (66 decibels or higher) of noise. At 66 decibels (dBA), most people find it difficult to have a conversation outside. The qualifying neighborhoods are prioritized statewide to receive traffic noise reduction as funding allows. The I-5 / 5th Avenue NE to NE 92nd Street Noise Wall Project was awarded funds as part of this statewide noise program.
How are neighborhoods prioritized for noise walls?
Neighborhoods are ranked based on a number of factors including cost of the wall, the level of noise from the freeway reaching their homes, the amount of noise reduction a wall will achieve for surrounding neighbors, and the number of people that will benefit from a wall.
How is noise modeled?
WSDOT builds a model of the project area to approximate noise levels. WSDOT then takes field noise measurements to verify the modeled noise levels. The model uses a variety of factors to determine the approximate existing and future noise levels in the project area. These factors include existing traffic noise levels, topography, and the locations of homes relative to the proposed location of a noise wall.
What are the current noise levels in the area?
Using noise samples collected on the west side of I-5, noise levels in this area range from 59 to 81 dBA. Noise levels on the east side of I-5 in this area range from 58 to to 77 dBA. Please download our noise thermometer image (pdf 282 kb) to learn more about varying activities and their approximate noise levels at certain distances.
Has WSDOT considered other methods to reduce noise?
WSDOT has selected quieter pavement test sites to see how quieter pavement performs in the Pacific Northwest's unique driving and climate conditions. WSDOT is studying the test sections of quieter pavement for five years to measure durability, quality and quantity of noise reduction, and how noise suppression abilities perform over time. This information will help policymakers, WSDOT, and others make more informed decisions about incorporating quieter pavement into highway projects in the future. Please visit the Quieter Pavement Web site for more information.
Has WSDOT considered re-paving the section of I-5 in this project area?
WSDOT is looking at methods to replace the pavement in this area, and experiencing some challenges with the existing pavement because it is not very thick and may easily break down when re-paved. For more information about pavement rehabilitation please visit WSDOT's I-5 Reconstruction Projects Web site.
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How much noise reduction will neighbors experience from a noise wall?
Given the characteristics of how noise travels, noise walls are most effective at reducing noise up to 500 feet from the edge of the traveled lane of I-5. The first row of houses behind a constructed noise wall may experience up to a 50 percent reduction in perceived freeway noise. Adjacent neighbors may experience noticeable reductions in freeway noise up to three rows back from the walls, depending on the topography.
Will a noise wall reduce all noise in my neighborhood?
Noise walls are constructed to reduce freeway noise, which sometimes masks other noises in the neighborhood. Once a wall is constructed, other noises in your neighborhood that are not coming from the freeway may become more noticeable.
Will a noise wall reflect noise over the freeway and into the neighborhood on the opposite side of I-5?
A wall on one side of the freeway is very unlikely to act as a "sound board," reflecting noise to the neighborhoods across the freeway. The I-5 corridor is very wide, and reflected noise would disperse very quickly, making it difficult to hear over the direct noise from I-5. Please visit the Federal Highway Administration’s highway traffic noise Web page for additional information about noise walls and how noise travels.
How will changes to my view be considered?
WSDOT recognizes that the proposed noise wall may block the scenic views that you and your neighbors enjoy. Before designing the noise walls in this area, WSDOT conducted a neighborhood poll to determine if the neighborhood supports constructing the noise walls.
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Who was eligible to participate in the community poll?
Property owners who have property behind the proposed noise wall and within 500 feet of the edge of the traveled lane of I-5 were eligible to participate in a community poll. This is because noise walls are designed to reduce noise in neighborhoods close to major highways. Given the characteristics of how noise travels, noise walls are most effective at reducing noise up to 500 feet from the edge of the traveled lane of I-5.
A poll for eligible property owners on the west side of I-5 (Stage 1) was conducted in June 2007. A poll for eligible property owners on the east side of I-5 (Stage 2) is was conducted in July 2008.
How did the community polls work?
WSDOT sent ballots and noise wall specific information to eligible property owners. The packets included information about the characteristics of the proposed noise wall closest to the property owner and a ballot. Only completed ballots were counted - if property owners did not return a completed ballot, their preferences were not included in the poll.
How were the ballots counted?
There was only one polling ballot per property. Property owners with a property closest to the noise wall (with a direct line of sight to the wall) had their ballots counted as 1.5 votes per property. All other properties within 500 feet of the edge of the traveled lane of I-5 had their ballots counted as 1.0 vote per property. When all ballots were recorded, WSDOT evaluated the results to gauge community support.
Why were the ballots weighted?
The ballots were weighted to reflect how different properties will benefit and be affected by the proximity to the proposed noise wall location. Property owners with a property closest to the wall (with a direct line of sight to the wall) will experience the most benefit from the noise wall and may experience other effects during construction and once the wall is completed. Examples of these potential effects include:
- Short-term construction effects (e.g., increased noise, artificial lighting, dust).
- Alterations, removal, or replacement of the property owner’s fence.
- Changes to outdoor use of property (e.g., planting areas, gardens, sitting areas).
- Unauthorized use of the space between the noise wall and chainlink fence.
- Increased shading and/or reduced natural light.
- Changes to landscaping near the proposed wall location, to accommodate construction.
How did WSDOT make the final decision regarding the noise wall?
The community poll is one of many sources of public input that WSDOT receives before continuing with the design and construction of noise walls. Other sources include correspondence with individual property owners, local community organizations, elected officials, and input collected from community meetings.
What were the results of the community polls?
WSDOT conducted separate polls for each Stage 2 noise wall (Walls 2, 3, or 4) in June 2007, and separate polls for each Stage 1 wall segment (Wall 1-North and Wall 1-South) in July 2008. Through these polls, the community expressed support for Walls 1-North, 2, 3, and 4. The results of the community poll, along with other feedback we received from Wall 1-South neighbors, did not signify support for the wall. As a result, WSDOT removed Wall 1-South from the project.
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