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.
Reason said construction costs in labor, material and equipment also increased compared to earlier estimates.
The 2.4-mile at-grade extension connects the Theater District in downtown Tacoma to the Hilltop neighborhood and St Joseph’s Hospital. The project adds six stations to the existing system and relocates the existing Theater District Station.
The project will also add five light rail vehicles (LRVs) to the system, bringing the total to eight, and expand the existing Operations and Maintenance Facility East to accommodate the additional LRVs. The extension requires the relocation of water and power lines, sewage pipes, and storm utilities out from under the track along the alignment. And Sound Transit plans on constructing four new traction power substations (TPSS) to power the overhead contact system.
The project will be completed as a design-bid-build contract package, as distinct from the design-build method Sound Transit has recently been using in an effort to expedite projects by selecting one contractor to both design and build the project.
Funding for the project is coming from three sources. The city of Tacoma is contributing $48 million with Sound Transit providing roughly $94 million. The rest of the money, $75 million, is coming from a Small Starts Grant from the Federal government. Greathouse said the agency recently learned that grant will be executed by the end of the year.
During a risk assessment, Sound Transit determined with 80 percent confidence the Tacoma Link Extension would begin operating in May 2022. Sound Transit anticipates a final design by the first quarter in 2018.
Greathouse said with construction yet to begin there are several risks before the agency. The top four risks have been identified as:
- Additional required roadway improvement and modifications.
- Unidentified utility conditions.
- Non-signalized intersections.
- Construction bids could exceed engineer’s estimate.
Actions by the board also approved changing the name of the project to the Tacoma Link Extension rather than calling it an “expansion”
and approved names the future stations which are: Old City Hall – 7th and Commerce. Stadium Way/S 4th – Stadium Way and S 4th S. Stadium District – N 1st St and N Tacoma Ave. Medical Center North – MLK Way and Division Ave. 6th Avenue – MLK Way and 6th Ave. Hilltop District – MLK Way and S 11th St. Medical Center South – MLK Way and S 19th St.
Correction: Station naming is still in progress, the Sound Transit Board is expected to hear the recommendations later this fall.