- 14.5-mile extension of the Metro Green Line Light Rail
- Multiple construction sites with different affected third parties and stakeholders
- Urban locations with limited access and right-of-way
- Excavations adjacent to active freight railroad
- Use of multiple types of SOE
- Challenging construction phasing requirements
- Coordination and review with multiple entities
Metropolitan Council has undertaken a 14.5-mile extension of the Metro Green Line Light Rail to serve the City of Minneapolis and neighboring municipalities. Much of the proposed alignment follows an existing freight rail corridor, which provided a path through the developed urban area but did not have adequate available space for the new double-track light rail. This required relocation of the existing freight rail within the corridor, replacement of existing sloped embankments with retaining walls, and reconstruction and widening of existing bridges to provide space within the highly-constrained existing right-of-way for the new dedicated light rail tracks.
Brierley Associates was retained by Lunda/CS McCrossan JV to design the support of excavation (SOE) elements at four sites along with the project, consisting of eight separate design submittals. Each structure presented its own challenges and constraints, with differing site conditions encountered between sites. Brierley worked with the LMJV to select constructable SOE systems for each site and structure to meet contract performance requirements, utilize on-hand materials owned by the LMJV, and minimize construction cost. These included soldier pile with timber lagging, sheet piles, and mechanically stabilized earth walls.