What was the problem?
There was unusual cracking in the concrete on the new HOV ramps. These cracks were parallel to cantilevered bus stops which jutted out on both sides of the ramps just to the north of the new NE 128th Street bridge. The cantilevered sections had also settled. WSDOT bridge specialists determined that these cracks resulted from a lack of sufficient steel reinforcement in the concrete supporting the cantilevered sections.
How large were the cracks?
The maximum width of the crack locations was one-tenth of an inch.
How much did the cantilevered sections settle?
The amount of the most significant settlement was 2.5 inches.
Who is responsible for this problem? Who’s going to pay for it?
WSDOT requested additional funding as part of its Supplemental Budget request to the Governor for consideration by the Washington State Legislature in the 2008 legislative session. The Legislature approved WSDOT’s request. This is intended as settlement of WSDOT’s cost responsibilities for the Totem Lake project. WSDOT remains committed to a successful partnership with Sound Transit in the design and construction of facilities in which the two agencies are in partnership.
Does the contractor bear any responsibility for this problem?
No. WSDOT engineers confirmed that contractor Max J. Kuney Construction of Spokane, Washington built the structures correctly and in accordance with the design.
Why didn’t you release information about this problem earlier?
WSDOT and our contractor noticed the cracks in December 2006 after we removed the temporary construction supports from the cantilevered sections. It took time to survey and inspect the structure and determine the cause and severity of the problem. We then proceeded to develop several designs to correct the problem. We chose the design in late January and presented this issue to the public in early February.
Is the structure safe?
The structure has never posed a safety risk to the traveling public. It had never been opened to traffic when we discovered the structural problem, and we have now repaired the problem. Engineers have inspected the structure thoroughly and have determined that it is safe for traffic.
How did you fix this problem?
We removed all of the concrete across the surface of the ramp, between and including the cantilevers. We installed additional steel reinforcing bars and poured new concrete. We further strengthened the replacement section by post-tensioning (tightening steel cables that run through ducts in the concrete).
How much will this cost?
WSDOT secured $6 million from the Washington State Legislature for the repair costs.
Did this delay the project?
We opened the ramps to and from the south of the new NE 128th Street bridge in April 2007. We opened the north ramps in November 2007.
Will these repairs require reconstruction of the art-stamped walls that support the ramps?
Replacing the cantilevered sections did not affect the art walls. We only reconstructed the top surface of the ramps and cantilevers. We placed plywood sheets over the art walls to protect them during the ramp repairs.
What did you learn from this? What will you do to make sure it doesn’t happen again?
WSDOT designs and reviews construction plans to ensure efficient construction of the thousands of safe and long-lasting facilities we have statewide. With lessons learned from the Totem Lake project, we have reviewed and improved our quality control and quality assurance process for our bridge designs.