The SR 520 Legislative Workgroup considered the following westside design options:
| Westside cost estimate |
Full corridor cost estimate | |
Option A+ Option A+ Recommended option |
$2.027B to $2.127B | $4.531B to $4.631B |
Option A Option A |
$2.022B to $2.298B | $4.526B to $4.802B |
Option K Option K |
$4.070B to $4.168B | $6.574B to $6.672B |
Option L Option L |
$2.562B to $2.642B | $5.066B to $5.146B |
Option M Option M |
$3.358B | $5.862 B |
The upcoming SR 520, I-5 to Medina: Bridge Replacement and HOV Project Supplemental Draft Environmental Impact Statement (SDEIS) analyzes three westside design options, A, K and L, each with sub-options.
The Option A+ recommendation is comprised of Option A with specific sub-options and is covered in the SDEIS.
While Option M also includes a tunnel underneath the Montlake Cut, it would require a different construction method than Option K, and is not covered in the SDEIS.