Background
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. Highway traffic noise along I-5, between 5th Avenue NE and NE 92nd Street, has been identified by the Washington State Department of Transportation (WSDOT) as a high priority for noise mitigation. WSDOT identified this as a priority because when WSDOT 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 has evaluated four noise walls along I-5 between 5th Avenue NE and NE 92nd Street. We are finalizing the design of three noise walls for the west side of I-5. Construction of these noise walls is scheduled to begin in late spring/summer 2008. In 2008, WSDOT plans to begin the design of one noise wall on the east side of I-5 in this area.
What is the project timeline?
2005-2007: Planning and public outreach begins.
2007: Design of noise walls located on the west side of I-5.
2008-2009: Construction of the west side walls.
Future Phase: WSDOT is coordinating the design and construction of the noise wall on the east side of I-5 with Sound Transit’s North Link light rail project that is proposed to be built in the same area.
Which neighborhoods will be affected by the 5th Avenue NE to NE 92nd Street Noise Wall Project?
Neighborhoods affected by this project include Maple Leaf, Licton Springs, and north Green Lake.
What is the project budget?
WSDOT received $14.3 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 is being used to design and construct three noise walls on the west side of I-5 and one noise wall on the east side of I-5.
What other factors affect the priority of noise wall construction?
Sound Transit plans to build a light rail line in the same vicinity as WSDOT’s proposed noise wall on the east side of I-5. WSDOT is concerned that if the wall is built now, it may need to be demolished and rebuilt to accommodate construction of the light rail extension in the future. WSDOT plans to coordinate with Sound Transit will to provide the best value and timing for the community.
Given the schedule and location conflicts, as well as neighborhood and legislative support, WSDOT is proceeding first with the noise walls on the west side of I-5. In addition to the opportunity to coordinate the noise wall project with Sound Transit, this option would also minimize construction impacts for residents on the east side of I-5 and use the current funding responsibly.
What happens to the east side wall if all the allocated funding is used up on the west side walls?
WSDOT has secured additional funding to address noise on the east side of I-5.
Can WSDOT build parts of the wall in the areas where there is no conflict with Sound Transit’s proposed light rail line? There are very few locations on the east side of I-5 where the noise wall location would not conflict with Sound Transit’s proposed light rail line. In addition, building smaller walls or segments of a wall may still permit highway traffic noise to travel around the walls and enter neighborhoods. It is important to have a long wall in order for the noise wall to be effective and successfully reduce noise levels.
Noise and Noise Walls
What is a noise wall?
A noise wall is a barrier constructed of concrete, wood, or earth that is built between a neighborhood and a freeway to reduce traffic noise. WSDOT generally uses concrete due to physical and financial constraints. These barriers vary in height and appearance depending on the location of their installation.
How does WSDOT decide where to build noise walls?
WSDOT considers constructing noise walls for two scenarios:
- 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 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.
- 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 ranked on the statewide priority list 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.
Why are some noisy neighborhoods not on the statewide noise wall priority list?
Only neighborhoods that were developed prior to May 14, 1976 can be considered for placement on the statewide noise wall priority list. This is because federal guidelines intended to provide noise relief for areas that existed before the policy was implemented. When I-5 was originally constructed, the increase in traffic noise was not addressed. Since the completion of I-5, new roadway improvement projects now include evaluation of noise walls or other treatments (as applicable) to reduce the net increase in noise, so these areas are not considered for the noise wall priority list.
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 – 81 dBA.
Has WSDOT considered other methods to reduce noise, such as quieter pavement?
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: http://www.wsdot.wa.gov/Projects/QuieterPavement/.
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: http://www.wsdot.wa.gov/Projects/I5/Rehab/.
After Construction
How much noise reduction will neighbors experience from a noise wall?
Noise reduction will depend on the height, length, and material of the wall, as well as the distance between each home and the wall. 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 my neighborhood?
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.
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 on the west side of I-5 in this area, WSDOT conducted a neighborhood poll to determine if the neighborhood supports constructing the noise walls. This poll took place during June 2007 and determined strong support to build the walls 2, 3 and 4.
How will the noise walls alter the landscaping near the freeway?
WSDOT will work with the community and the construction team to help minimize effects to trees and other landscaping. To accommodate the equipment needed for construction, WSDOT will likely need to remove some trees nearest the proposed noise wall locations. When the project is completed we will replant to re-establish vegetation lost along the roadside during construction.
What design treatment will be used for Walls 2, 3, and 4?
During summer 2007, WSDOT held a design workshop for property owners near Walls 2, 3, and 4. Neighbors were asked to provide input on the design treatments for the neighborhood side of the noise walls. Based on community preference, we will design the neighborhood side of each wall using the following patterns:
• Wall 2 - Ashlar stone pattern
• Wall 3 - Ashlar stone pattern
• Wall 4 - Dry stack stone pattern
Public Involvement
How is the public involved in a noise wall project?
The opinions of affected property owners may influence the location, height, length, and appearance of noise walls that will be built in their neighborhood. WSDOT would like the public to be involved in all stages of the noise wall project. Feedback from the community is critical during the design of this project to ensure all reasonable requests are included in the project plans. WSDOT provides formal opportunities to engage the public in the decision making process through community organization briefings and open house meetings, and welcomes input from individuals. WSDOT also conducted a poll of property owners near the proposed west side noise walls to gauge community support for constructing noise walls.
How does WSDOT evaluate public feedback?
All feedback from the public will be recorded and considered. WSDOT’s policy is to build noise walls in neighborhoods on the priority list as funding becomes available. However, if a neighborhood majority does not want a wall, WSDOT will not build it. Residents will have the opportunity to provide input via e-mail, phone, and during community meetings.
WSDOT polled property owners within 500-feet of the proposed noise walls on the west side of I-5 in June 2007. Nearly 60% of eligible property owners participated, with 95% indicating their support for the project. The results of the community poll, along with other feedback we’ve received show strong support for the wall.
Who participated in the poll on the noise walls on the west side of I-5?
Property owners who have property behind the proposed noise walls on the west side of I-5 and within 500 feet of the edge of the traveled lane of I-5 were eligible to participate in the poll in June 2007. 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.
How did the community poll work?
WSDOT sent ballots and noise wall specific information to eligible property owners behind each of the three noise walls on June 8, 2007. The packets included information about the characteristics of the proposed noise wall closest to the property owner and a ballot. Ballots postmarked by June 25, 2007 were considered. Only completed ballots were counted - if property owners did not return a completed ballot, their preferences were not be included in the poll.
How were the ballots counted?
One ballot was sent to the eligible property owner(s) of each property. Ballots returned from property owners with a property closest to the wall (with a direct line of sight to the wall) were counted as 1.5 votes per property. Ballots received from all other properties within 500 feet of the edge of the traveled lane of I-5 were counted as 1.0 vote per property. Once 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 or removal and 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
• Maintenance agreements established between property owners and WSDOT
• 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 was one of many sources of public input that WSDOT received 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 the May 31, 2007 community open house.