We signed a design-build contract with Seattle Tunnel Partners in January 2011. Design-build combines project design and construction in a single contract.

More than 90 percent of the design-build work will be performed for a fixed price. The remaining amount includes work such as grouting to control ground settlement, building repairs along the tunnel route, unplanned repairs to the boring machine and work stoppages due to differing site conditions. For these items, we established risk sharing with the design-builder.

We have set aside $205 million for known and unknown risks during tunnel construction. This amounts to 15 percent of the design-build contract, which is on the high end of industry standards.