Stretching over highways and busy intersections, squeezing into existing rights-of-way with active rail lines,  touching a major college campus and a veteran’s hospital, the $2.1-billion Mid-Coast Trolley extension is visible throughout San Diego. Not only will it play a key role in the mobility vision of the San Diego Association of Governments (SANDAG), it is influencing other development in the region as well.

The 11-mile extension, called the Blue Line, begins just north of the Old Town Transit Center and travels in an existing railroad right-of-way and alongside Interstate 5 to Gilman Drive. It crosses to the west side of I-5 just south of Nobel Drive and continues on to serve the heart of the University of California San Diego campus. It then crosses back to the east side of I-5 near Voigt Drive to serve the UCSD east campus and Scripps Memorial Hospital, transitions into the median of Genesee Avenue and continues down Genesee to the UTC Transit Center.

The project was partially paid for by a Full Funding Grant Agreement (FFGA) from the federal government in 2016, which covered about 50% of the total cost. The rest is being funded by voter-approved sales tax funds, called TransNet. Mid-Coast Transit Constructors (MCTC), a joint venture of Stacy & Witbeck Inc., Skanska USA and Herzog Contracting Corp., began work that year, brought onto the project at the 65% design level. The team worked with SANDAG and designer WSP to conduct constructibility reviews.

MCTC has reached the halfway point, working under a $1.3-billion construction manager-general contractor (CM/GC) agreement.

“It includes a lot of individual little contracts,” says Ben Steele, MCTC project engineer for Segments 3 and 4. As construction progressed, the team ended up taking on extra projects such as the Gilman Bridge at the UCSD campus. The bridge was not supposed to be built until sometime in the future, but “we worked it out with the campus that we would only hit them one time,” says John Haggerty, SANDAG project director. Other add-on work comes to about $300 million, he says.

The first 6.5 miles, Segments 1 and 2, start at the Santa Fe Depot and include upgraded track, substations and signals for the existing trolley line, says Haggerty. The extension heads north, crossing or paralleling I-5 in the same ROW as the BNSF railroad and Amtrak. “We’re adding two tracks of light rail in that segment,” says Haggerty. That work includes building bridges over the San Diego River, a creek and Balboa Avenue, plus three bridges over Rose Creek and under Gilman Drive.  

“When we first started looking at the project, part of our whole process was looking at sequencing—even before the team came on board—with our own design team,” Haggerty says. “A lot of the benefit we got from CM/GC was bringing them on during design to set up how to implement construction and in what order.”

Working with the North County Transportation District and the San Diego Metropolitan Transportation System, “we realized if we built it without these other double-track projects, it would be very difficult to come back later and do those. Essentially, the agencies juggled a bit of work to bring those forward and do them as part of the Mid-Coast Trolley extension. Then the university asked us to coordinate with them, so we added that work to get in and out in one shot and not have multiple contractors in a tight area,” Haggerty says.

Campus Collaboration

Multiple contractors will be there in the future because the university is planning billions in capital work, says Joel King, assistant vice chancellor of design and development services and campus architect for UCSD. “With the advent of the FFGA, we began to meet in earnest with SANDAG about the trolley coming to the campus. Initially, there was debate whether it would even land here or not.”

Early thoughts about a cut-and-cover tunnel and at-grade tracks on campus gave way to a fully elevated scheme after discussions with SANDAG, says King. UCSD officials showed the agency a visual simulation of how the original alignment would affect the campus’ existing and planned infrastructure. “SANDAG listened to our concerns and went back to the drawing board and realigned the guideway and relocated the stations,” he says.

The 400-ft-long Gilman Bridge, completed this February, had been planned for years, adds King. Designed by a team led by Moffatt & Nichol, the three-arch concrete structure spans I-5 and connects the east and west UCSD campuses.

Another collaboration emerged when UCSD agreed to have the rail alignment run along its east campus rather than at Scripps Hospital, a competing medical facility. That meant the contracting team didn’t have to work with more owners. “We had established a relationship with SANDAG and its team that was key. Regarding day-to-day happenings in the field, we really have developed this relationship of trust,” King says.

That led to more flexibility for the contracting team to move fencing, close roads or conduct materials operations, says David Smith, MCTC construction manager for Segments 3 and 4. The team is working with more than 20 stakeholders, including the city of San Diego and private developers like Westfield UTC and Irvine Co.

Segments 3 and 4 include one 150-ft section of cut-and-cover tunnel and four miles of elevated guideway, says Steele. The amount of falsework is vast—including 20 million lb of steel beams. There’s also 26.5 million lb of rebar for the bridges, adds Smith. But in the case of the Genesee Bridge, MCTC decided to eliminate months of falsework and street closures in favor of precast concrete beams. “They had originally proposed cast-in-place, but then they looked at the staging and intersections and concluded precast could work and would be much faster,” Haggerty says.

A total of 142 precast girders, some up to 70 ft long and weighing nearly 100 tons, traveled 75 miles from Perris, Calif. They were set during a five-day closure and saved about nine months on the schedule. “We were allowed six days, but opened the intersection back up in five days,” Smith says. “When you do that, the trust level goes up.”

The contractor came up with numerous other in-field solutions, made possible by the CM/GC, says Haggerty. For example, crews replaced mechanically stabilized earth walls with precast vertical member walls that are backfilled and stacked.  They also used a joint trench to relocate utilities on Genesee Avenue, says Dan Heiman, structures manager for MCTC. Utilities have been a challenge, with many unknown conditions, “but we are working with SANDAG to get through them,” says Smith.

The original guaranteed maximum price of $926 million has increased by about 10% due to change orders, says Haggerty. “When we negotiated the GMP, there were elements not as far along in design. But we really needed to get into construction. We put provisional sums in the contract. We had best estimates—elevators, station finishes, ancillary buildings, etc. The bids from subcontractors on that negotiated work are coming in at higher cost. We take that risk as an agency.”

Planning Ahead

The project, set to open in July 2021, is part of a larger transportation plan for the region, says Gia Ballash, spokeswoman for SANDAG. “We’re looking to increase multimodal options within the region and get San Diego to a place where communities can connect.”

That includes bike paths incorporated into the bridges and connections at the nine new stations to existing bus service. “We’re planning a mobility hub where we are looking at automated vehicles, first and last miles, electric scooters,” says Haggerty. “The infrastructure in this project will allow for all of that. We’re planning for a lot of information technology infrastructure.”

Although ridership when the extension opens is projected at 21,000 on the first day, that number may be conservative, considering that UCSD students have consistently voted to include transit passes in their fees. Population in the corridor is forecast to increase by 19%. And the student population has grown from 20,000 to 36,000 in six years, says King. “There is pressure for more infrastructure and housing. Our chancellor envisions a live-learn residential campus where students living on campus will increase from 40% to 60%. Our capital plan is to increase resident beds from 13,000 to over 20,000.”

At one of the stations, UCSD plans a 1,500-bed tower with no parking. “We have never done that before,” says King. “It speaks to the future.”