Sound Transit is getting close to releasing the results of the North Corridor Alternatives Analysis (AA) and has started to brief partner agencies on the draft results. We wrote about the alternatives analysis previously. While bus options are being considered the most relevant question this analysis will answer is how different Link alignments, I-5 and SR-99 compare. Above is a table taken from a ST briefing given to the Edmonds City Council on August 2nd.
The draft results conclude that a SR-99 alignment would be 1.7 miles longer, require 10 additional trains for the segment, have a segment travel time of 4 more minutes, have 4,000 fewer daily riders, benefit new riders less and generally have the same environmental impacts beside impacts to properties.
More after the jump.
The slide below summarizes the impact these differences have on the costs and performance of the project. The alternatives analysis estimates that a SR-99 alignment would be between $590-670 million more than an I-5 alignment. The I-5 alignment is roughly half at grade, while the SR-99 is entirely elevated. This, in addition to the 1.7 miles of additional guideway and higher costs associated with working in the already developed and constrained ROW along SR-99 most certainly contribute to the higher costs. Due to higher cost and fewer new passengers the SR-99 alignment has significantly higher costs per new passenger.
The finalized alternatives analysis findings will be released mid September. I think it would be best to hold off on judgement until the details of the study are released.