Year: 2012

Milepost 31 Speaker Series – Protecting structures along the SR 99 tunnel route

Safety is WSDOT’s number one priority on the SR 99 Tunnel Project. This includes protecting buildings, utilities and roadways above and near the tunnel route. Learn how advanced technology will allow WSDOT to keep a continuous eye on the ground around the tunnel before, during and after construction.

6 to 6:30 p.m.
Thursday, Oct. 4

Milepost 31

211 First Ave. S., Seattle

Admission is free.

After the talk, be sure to leave enough time to explore the rest of the First Thursday Art Walk in Pioneer Square. Milepost 31 is open Tuesdays through Saturdays from 11 a.m. to 5 p.m., and stays open until 8 p.m. on First Thursdays.

Tunneling toward a new SR 99 corridor

At 57.5 feet in diameter – roughly as tall as a five-story building – the SR 99 tunnel boring machine will be the world’s largest. Crews are currently assembling the machine in Japan. It will be tested, taken apart and barged to Seattle in more than 40 pieces, which will be reassembled in an 80-foot-deep launch pit to the west of Seattle’s stadiums. The first pieces of the machine will begin arriving early next year, and tunneling is scheduled to start next summer.

Curious how the tunnel boring machine will work? Check out the 10-foot-long, motorized scale model on display at Milepost 31 for an up-close look at the machine’s inner workings.

Seattle Parks and Recreation completed the installation of a temporary protection bollard for the Pioneer Square Pergola. The new bollard is anchored by a structural pipe set into the ground and provides extra strength and protection for the historical Pergola. The temporary bollard will be replaced when the fabrication and delivery of the permanent decorative bollard is completed. Parks removed the temporary cement blocks that were installed to provide short-term protection and installed a new concrete ramp from the street.

The installation of a new cornice piece on the Pergola is scheduled for the weekend of October 20-21. The required work is adjacent to the electric trolley lines on First Avenue requiring the lines to be temporarily deactivated while the work proceeds. While the work occurs, the right lane of north bound First Avenue will be temporarily blocked during the installation operations to allow for a boom lift to assist in placing the restored cornice piece.

Parks anticipates the installation of the permanent decorative bollard will occur in November.  This project will take about two hours and have minimal impact to the area.

In 2001 the Pergola was hit and knocked down by a semi-truck. The Pergola was completely renovated at that time, and a surface mount bollard was installed to protect the historical structure from further strikes. However, the Pergola and bollard have been hit several times since 2001, necessitating repair and reinstallation of the old bollard. Now Seattle Parks and Recreation is collaborating with the Seattle Department of Transportation to install an in-ground bollard that will provide even more protection to keep this iconic piece of Seattle’s past intact.

Constructed in 1909, the Pergola in Pioneer Square Park provided shelter for passengers waiting for the cable car that ran along Yesler Way. It was built in a Victorian style, out of iron and glass. It was restored in 1972, and designated a historic landmark in 1977.

For more information on the project, please contact Ron Wright of Ron Wright and Associates at

rwright@rwaa.com or 206-728-4248.