San Diego Blue Line Transit Expansion (MCTC)

Game-changing transit for San Diego region - expanding system by 20 percent

Mid-Coast Extension of UC San Diego Blue Line Trolley (MCTC)

One of the largest infrastructure projects in San Diego’s history, the $2.1 billion Mid-Coast Trolley Extension was over 5 years in construction. This much-anticipated transit line extension offers a transfer-free ride from the U.S.-Mexico International Border and communities south of downtown San Diego all the way to the University Community area.

The 17km [11 mile] long double-track light rail extension runs along the right-of-way of San Diego’s Coaster Railway Service and the I5 with a total nine new stations – four at-grade and five aerial.

We offered our transit expertise to the five aerial stations by providing spider support systems to the station’s soaring elevator towers (connecting pedestrians from ground to trolley platform). Our heavy-duty SS20 spiders were paired with our articulating glass bolts and affixed the vertical glass surrounds to the eight towers at these stations as well as supporting corresponding canopies.

We faced a “Made in America” design requirement for our in-house designed materials meaning we needed to source new vendors. One of our new key vendors also makes rocket ships for NASA so we knew our clients were in good hands.

The project’s hardware finish was another bespoke modification by us; our hardware truly “sparkles like jewelry” on the transparent elevator towers. Our typical finish is No. 4 – 320 Grit (brushed) but for this project, we had the hardware polished to a mirror finish. This was an extensive process when you consider our AB602 bolt has over 6 pieces to be dis-assembled, polished, quality-checked and re-assembled (and over 4,000 of them were used in this project).

With regards to scope size, the elevator towers rise high in the air at over three stories tall; our spider assemblies supported over 1,800 sq. ft of glass on each tower. Multiple that by the 8 (for each of the eight towers worked on) and that’s a lot of glass (rough estimates of over 1,000 spider assemblies were supplied).

As is typical for our approach, we stayed close to the project during install providing a Stella Solution when an electrical conduit was added to the towers and needed to be affixed to overall structure (we won’t give away all our secrets but we were able to modify our glass bolt to tie conduit into system).

Project Team

In a project like this – team work is essential. Per MCTC “At the end of the day, it all came down to the kind of people and the culture that the job had, and we had people willing to solve problems and move the project forward.”

• Lead by San Diego Association of Governments (SANDAG)
• Construction Manager/General Contractor – Mid-Coast Transit Constructors, a joint venture firm of Stacy & Witbeck, Inc., Skanska USA, and Herzog Contracting Corporation
• Lead Environmental and Engineering Consultant/Designer of Record – WSP
• Project Management Extension to Senior Staff at SANDAG – HDR, in partnership with TY Lin International
• Glazing Contractor – Tower Glass Inc.
• Glass Engineer – Rice Engineering

Interesting project info:

• Blue Line has the highest ridership of San Diego Trolley’s three regular lines
• Construction spanned over five years; challenges from a construction perspective included six locations where precast girder spans crossed over live traffic and the design requirement to keep major intersections open and operational throughout construction
• Stations we worked on:
  • UTC – Westfield
  • Executive Drive (photo images are of this station)
  • UC San Diego Health La Jolla
  • UC San Diego Central Campus
  • Nobel Drive

Source Info: 

– Mass Transit Publication – May 2022 – “Mid-Coast Corridor Program Delivered with a Project-First Mentality”
– Engineering News-Record – “Award of Merit – Airport/Transit: Mid-Coast Extension of the UC San Diego Blue Line Trolley” 
– WSP Blog –“San Diego Welcomes the Arrival of Mid-Coast Trolley Blue Line Extension”
– HDR Role here