By 2015, Sound Transit had already grown the project from a 1.3-mile expansion with two new stations in 2008 to a 2.4-mile extension with six new stations. At the end of the preliminary engineering stage of the project, the agency submitted a cost of $175 million for the extension.
“That [$175 million] reflected the scope at the time, at a very preliminary level of design and the market conditions suitable for that year,” Madeleine Greathouse, a construction management specialist with Sound Transit, told the board at its September 28 monthly meeting. “The baseline estimate before you today is based on the latest information with regard to current market conditions as well as the evolution of design from earlier stages of planning and scope refinements.”
Greathouse emphasized the cost estimate was still within the range identified in ST2 when escalated to year-of-expenditure dollars.
According to Kimberly M. Reason, spokesperson for Sound Transit, further design refinements between the preliminary engineering and 60 percent design stage included “changing from ballast to embedded track at the Operations and Maintenance Facility, larger track power substations and associated equipment and utilities, and increased quantities of Overhead Catenary Supply poles.” And additional engineering from the city found the need to install 40 new ADA curb ramps not previously identified.
“Real estate acquisition was not a significant driver of cost growth as the project does not require complete or full parcel acquisitions,” added Reason in an email.