SRK Engineering is currently utilizing All the Walls’ Stresswall precast post-tensioned/prestressed counterfort wall system for the Midcoast Corridor Transit Project. The MCTC project extends the light rail from Old Town north to UCSD and La Jolla. It also adds a second heavy rail track through the entire Midcoast corridor.
The Midcoast rail corridor runs through Rose Creek Canyon with 4 tracks: 2 light and 2 heavy E 80 rail. Due to the additional live tracks, there is a need for many different retaining walls along the alignment. There are both cut and fill wall applications since the track grade is also being raised in places to be above the 100-year flood elevation.
SRK Engineering and All the Walls approached MCTC (the general contractor for the project) with the Stresswall design for an alternative, cost effective option that met or exceeded all of the E 80 and LRT load criteria.
Walls 508 and 563 were originally designed as CIDH soldier pile walls with two-stage tiebacks. Conventional walls of this type would be very expensive and time consuming to construct, as well as the associated inherent risks involved with drilling in difficult areas.
After months of extensive design review meetings with SANDAG, NCTD, WSP, HDR, TY Linn and other design firms, the Stresswall option was approved for construction. The acceptance of the Stresswall system on this project saved millions of dollars in construction costs that were credited back to SANDAG and MCTC and also saved months on the critical path construction schedule. Construction of these walls has gone very well and all parties are pleased with the design and final product.
Wall 482 ( 4,500 sq. ft.) was built over a weekend with two crews working around the clock while the track was shutdown. This site was excavated and the precast components installed and backfilled in 47 straight hours. The original approved plan design was an MSE wall backfilled with Cellcrete, which would not have been cost effective.
Walls 600 and 624 were both originally designed as MSE walls, however North County Transit District (NCTD) no longer allows MSE walls to be built to support their track embankments, so Stresswall was selected as the most viable alternative. The change to Stresswall eliminated the shoring that would have otherwise been required for MSE walls, resulting in substantial excavation savings while providing a superior product.
This project used All the Walls’ patented proprietary retaining wall system. It was also awarded PCI’s 2019 Best Non Highway Bridge Project.
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