Parking fills up early at stations like Puyallup, but at what price tag should we add more garages? (image: Sound Transit)

Several future parking expansions for Sounder South stations are projected to come in far above earlier cost estimates. On Thursday, the Sound Transit Board is expected to approve a 675 stall garage at Auburn Station that will cost $120 million, 54% more than the previously approved financial plan.

At Sumner Station, Sound Transit intends to spend $81 million for a 623 stall garage, 41% above the earlier estimate. Sound Transit is selecting a project to be built at Kent Station, where the cost of a 534 stall garage has grown to $117 million, already 29% above the previous estimate.

The price tag per stall is extreme. Each of these planned structures are on sites with existing surface parking. At Sumner, the cost is $160,000 for each of the 505 net new stalls. In Auburn, the 555 net new stalls will cost $216,000 each. Even these dizzy numbers pale in comparison to Kent station where Sound Transit plans to spend $278,000 for each of the 420 net new stalls.