Megaprojects are keeping construction crews hopping in California and Hawaii. Five projects on ENR California's 2013 Top Starts list are valued at more than $1 billion; in 2012 only one project exceeded the $1-billion level.

The current ranking, which highlights the 30 largest projects to break ground in California during 2013, features a broad mix of project types, including health care, highway, transit, commercial and water/infrastructure. New this year, Hawaii's active construction market is represented in a separate chart.

The largest project to break ground last year, the $2.25-billion Antelope Valley Solar Power Plant, comprises two co-located photovoltaic plants spanning 3,230 acres in Kern and Los Angeles counties. The project will generate 579 MW of power upon completion in November 2015.

But overall, solar power continues to dim, with Antelope being the only such project on the ranking. Two years ago, solar projects occupied the top five spots.

Of the four health care projects on the current list, the largest is the $2-billion Stanford Hospital, located at the Stanford University Medical Center campus in Palo Alto. The 812,000-sq-ft replacement hospital includes 368 individual patient rooms, an emergency department and diagnostic and treatment rooms within a seven-story, steel-framed building. The exterior system features dual panes of glass that sandwich automatically controlled blinds to regulate energy use.

The highway and bridge sector returns to the top 10 with two projects, after being largely absent on the previous year's chart. The largest is the $1.3-billion 91 Project, which adds one regular lane and two tolled express lanes in both directions of State Route 91 in Corona, plus an extra toll lane in each direction on Interstate 15 and new connectors between both freeways.

The project is funded by a multifaceted financing package, including a local half-cent sales tax, state and federal funding and toll revenue bonds, according to administrators with the Riverside County Transportation Commission. Joint venture contractor Akinson Walsh began early geotechnical and land-clearing work after receiving notice to proceed on a $632.6-million design-build contract in October 2013, but large-scale work isn't expected to begin until this summer.

Airports and Mass Transit

The largest airport start in California since 2010's $1.5-billion Tom Bradley International Terminal is the $316-million Consolidated Rental Car Center at San Diego Airport. An Austin-Sundt joint venture is building the 2-million-sq-ft, cast-in-place concrete structure.

Numerous piles remain in the 24.5-acre site from previously demolished buildings—a big hurdle for crews installing the 3,000 piles for the new building that are required to overcome poor soil conditions. "It would be cost-prohibitive to remove the abandoned piles, so we're building around and over them by potholing critical locations and modeling the foundations prior to construction," says Sundt preconstruction project manager Brad Kirsch.