Property Owner Information

SR 99 Tunnel Project - Information for Property Owners

December 2014 - Information for residents and businesses in Pioneer Square

Recently, our team detected approximately one inch of ground settlement near the pit Seattle Tunnel Partners is building to access and repair the SR 99 tunneling machine. Settlement was also detected on the Alaskan Way Viaduct and some of the buildings that we are monitoring; the amount of settlement lessens in the surrounding area. Our experts are still analyzing data and conducting daily inspections of the viaduct, but to date, no significant settlement has been observed beyond the initial settlement we reported publically on Dec. 5, 2014. 

We have identified approximately 50 buildings that warrant further investigation. We are working with property owners and managers to complete interior visual inspections of these buildings. These inspections are being completed by a historic architect and include a survey of the building to look for impacts to significant architectural elements or other indications of damage.
We’ve received a number of questions from residents and businesses in Pioneer Square regarding recently measured ground settlement in the neighborhood. Below are answers to some of the most common questions. We’ll continue to update this list as we gather additional information. If you live, work or own property in Pioneer Square and have questions or concerns, please call 1-888-AWV-LINE or email
The Washington State Department of Transportation is a public agency and is subject to the State of Washington’s Public Records Act (RCW 42.56). Therefore, public comments and questions may be made available to anyone requesting them for non-commercial purposes.

Common Questions for residents and businesses in Pioneer Square

What kind of settlement has WSDOT seen near the access pit and in Pioneer Square?

In late November, Seattle Tunnel Partners surveyors detected a little over an inch of ground settlement near the pit crews are building to access and repair the SR 99 tunneling machine. We have also seen similar settlement on the Alaskan Way Viaduct; the amount of settlement lessens in the surrounding area.  Settlement levels in the area have remained stable since Nov. 24, but we continue to closely monitor the area. The investigation into the source of this settlement is continuing.

Have buildings been damaged in Pioneer Square?

We have worked with property owners and managers to complete approximately 50 visual assessments of buildings in areas of greater ground settlement.  During these assessments, an architect with expertise in historic buildings checked portions of each building to look for signs of recent damage that might require immediate attention. So far, a small amount of recent cosmetic cracking has been noted in some buildings. Most buildings have shown no signs of recent settlement. 

How would settlement affect a building?

You may notice new cracks or changes to existing cracks. You may also notice doors or windows that are sticking or do not open properly.  If the building settles more than the ground outside, utility services also could be affected. If you notice such changes in your building, please keep a list or take photos, and follow the contact information below.

What should I do if I see new damage in my building?

If you are a resident or tenant, please contact your property manager or building owner. Building owners should contact the Alaskan Way Viaduct Replacement Program (1-888-AWV-LINE or to report any settlement-related concerns. A WSDOT representative will contact you to arrange for a mutually convenient time to inspect your building. If you have photos, please share them with our staff.

How do I file a claim if I have building damage?

If you feel your building has been damaged as a result of ground settlement caused by the project, you can contact us at 1-888-AWV-LINE or

What is WSDOT doing to monitor buildings?

We implemented a comprehensive program to monitor ground movement during SR 99 tunnel construction. Crews are currently analyzing data from this system and conducting extensive surveys near the work zone.

For buildings closest to the tunnel route, crews previously conducted pre-construction surveys that incorporated photo and video to document each building’s interior and exterior condition. We will be conducting similar building condition surveys for additional buildings within Pioneer Square. These survey results will serve as a resource for both property owners and the project team by documenting the current condition of each building.     

Can WSDOT expand the monitoring program to include more buildings?

Our monitoring system was designed to measure ground movement during tunneling. As part of that system, monitors were installed both in the ground and on structures. The most significant recent settlement has occurred in areas that already include both ground and building monitors. However, some settlement has been observed in areas that are not actively monitored. As a result, we do not have specific settlement data for some of these buildings.   

Structural engineers and surveyors are inspecting buildings and infrastructure in all areas where settlement was detected. Decisions about expanding the scope of the monitoring program will be made after that analysis is completed.

Does WSDOT have a plan if settlement continues?

Settlement levels in the area have remained stable since Nov. 24, but we continue to closely monitor the area. Protecting people and infrastructure is our top priority. Protocols are in place to address a range of potential issues that could arise as a result of ground settlement. 


General information for property owners

The SR 99 Tunnel Project is one of the largest excavation projects in the history of our state. The project’s five-story-tall tunneling machine will remove approximately one million cubic yards of soil by the time it finishes digging the tunnel. The ground naturally experiences movement over time, but digging underground can cause additional movement.

We have implemented a comprehensive program to monitor and mitigate any effects of tunneling. The following information is intended to be a guide for property owners above and near the SR 99 tunnel route.


If you have questions, please email us at or call our hotline at 1-888-AWV-LINE (298-5463).

Common Questions related to tunneling

How is WSDOT protecting structures along the tunnel route?

Buildings, utilities and streets located above and near the tunnel route will be monitored before, during and after construction. Each building was surveyed prior to construction to document its interior and exterior condition. Monitors installed on the buildings by our crews will be checked against data from before construction, as well as data from monitors installed outside the monitoring area.  As the tunneling machine pushes forward through earth, crews will measure the soil it removes while also tracking any ground movement above its path. If damage does occur to buildings, utilities or streets as a result of tunnel construction, we will be responsible for costs associated with repairs.

What types of monitoring equipment are installed on buildings?

Crews have installed monitoring equipment on buildings along the tunnel route. Automated survey machines on rooftops rotate and take readings of small monitoring points on nearby buildings every few seconds to measure any movement. They also use lasers to take measurements of reference points on the ground. Information from these machines is transmitted and recorded around the clock and reviewed by the project team.      

When taking readings, the survey machines emit a red beam that is similar to a laser pointer. The beam may be briefly visible. Each reading takes less than one second and is not harmful if seen.

What happens if damage occurs to my building during tunnel construction?

If we receive a report of damage to buildings or infrastructure, we will assess the damage and determine the cause. We will be responsible for repairing damage that occurs as a result of tunnel construction. Our staff in the Seattle project office will work with property owners to address claims. 

Crews have conducted pre-construction surveys that document each building’s interior and exterior condition prior to tunneling. This survey will help building owners and our structural experts quickly determine if any damage occurred as a result of tunnel construction.   

To report property damage or discuss any concerns during tunneling, please contact us at 1-888-AWV-LINE (298-5463) or The hotline is answered 24 hours a day, seven days a week.

When will the tunneling machine be near my building?

The tunneling machine began its journey under downtown Seattle in summer 2013. In December 2013, Seattle Tunnel Partners, our contractor for the tunnel project, stopped excavation approximately 1,000 feet into the dig after measuring increased temperatures in the tunneling machine. While investigating the cause of the high temperatures, STP discovered damage to the machine’s seal system and contamination within the main bearing.

STP is now building a 120-foot-deep pit that will allow crews to access and repair the machine, which is stopped about 60 feet underground between South Jackson and South Main streets. When the pit is complete, the machine will tunnel forward into it. Crews will then partially disassemble the machine, and make repairs and enhancements. After tunneling resumes, we will contact you to let you know when the machine will be close to your property.

Will I be able to hear or feel the tunneling machine?

It is possible that you may hear some noise or feel slight vibrations while the tunneling machine is near your building. If perceptible, noise and vibrations would last less than one week as the machine passes beneath.

Will my building be damaged during tunneling?

It is unlikely that your building will be damaged during tunneling. The machine was designed specifically for the soil and groundwater conditions beneath Seattle. As a result, we do not anticipate significant levels of settlement from tunnel construction. If any damage occurs as a result of tunnel construction, we will be responsible for repairs.