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SR 520 – Portage Bay Bridge and Roanoke Lid Project – Vibration

What to expect

This project will have heavy construction activities, such as pile installation and removing the existing roadway, that could cause vibrations in the surrounding neighborhoods.

Pile installation

Pile installation involves driving a long metal tube (pile) into the ground or a lakebed to provide the foundation for a structure. To avoid the noise that comes with repeatedly striking a pile with a hammer, the contractor will primarily use a vibratory device that shakes the pile into the ground. In some cases, vibratory hammers can produce enough vibration for you to feel or see in your home. For example, the vibration levels can rattle dishes or make guitar strings hum but are not high enough to knock pictures off the wall. After a pile has been vibrated to a certain depth, the contactor may use an impact hammer during the day (which makes the loud “bang-bang” noise) to ensure the pile is lodged securely.

Picture of a vibratory hammer driving a pile into the ground
Picture of a vibratory hammer driving a pile into the ground

Bridge removal

You also can expect some vibration when we remove parts of the current bridge, as well as the existing 10th Avenue East and Delmar Drive East bridges. This work involves using hydraulic breakers and concrete saws to cut apart and haul away roadway structures in sections. Soil conditions, building types, and proximity to the construction area will affect how much you feel vibration.

Strategies and resources

Test pile installation

This summer, we will install a test pile near the eastern shore of Portage Bay to measure vibration levels and inform vibration limit requirements on the project. These limits will be written into the project contract, and the contractor will be required to minimize vibration effects. Vibration will be monitored continuously throughout the test installation.

Property inspections

Before construction begins, we will reach out to neighbors living close to the construction area to schedule before- and after-construction home inspections. These inspections are free of charge. Neighbors can also request an inspection before or during construction.

In the unlikely event a home experiences damage from vibration, the inspection creates a baseline that helps shorten and simplify the reimbursement process. If, at any time during or after construction, residents notice potential property damage, they can reach out to us to schedule an inspection to assess the damage.

Vibration damage fund

In the unlikely event construction has damaged a property, we have created a vibration damage fund for damages up to $15,000. This expedited reimbursement program allows our contractor to directly reimburse an affected household up to $15,000 rather than going through the traditional tort claim process.

Vibration monitoring

The contractor will be required to install and operate vibration meters near the project.