As with most public projects built since 9/11, great attention was paid to threat and vulnerability risk assessment requirements in the “bus box” and surrounding area. Support columns, for example, include one-in.-thick steel plate on the outside to prevent a chain-reaction explosion in case a bomb were to be placed against a column. Some trash containers outside the bus facility are made of clear plastic, so authorities can see if something dangerous is inside.

Tall Task

The bus facility measures 1,100 ft long and 150 ft wide, and sits 23 ft below grade. The passenger concourse alone includes 44,000 sq ft. Because the facility is below the Central Platte Valley water table, its exterior walls are two ft thick and the floor is four ft thick to keep it watertight. The dirt that was excavated for the structure—roughly 150,000 cu yd—was recycled as backfill.

If the bus facility were stood on end lengthwise, it would be the tallest building in Denver, according to Kristopher Takacs, associate director and Union Station project manager for SOM, New York City. SOM also designed Denver’s—and the Rocky Mountain West’s—tallest existing building, the 56-story, 714-ft-tall Republic Plaza skyscraper.

“The bus terminal is a major transportation project by itself, and the fact that it’s underground is unusual for a bus terminal,” Takacs says. “That made it all the more important that it became part of the public space. We took great care that there was a visual connection with daylight above from skylights and finishes that would be world-class.”

Kiewit had to pump and treat a significant amount of water to accommodate the bus facility. “We had pumps taking out 600 to 1,200 gal. per minute at one point,” said Haptonhall. “We were one of the first projects to remove arsenic successfully from groundwater.”

The above-grade commuter rail train hall, located just east and above the bus facility, serves existing Amtrak commuter rail as well as six new commuter lines FasTracks will bring to the station.

The hall includes one of the transit project’s set piece—a sweeping white-roof canopy with a weblike steel frame covered with the same polytetrafluorethylene (PTFE) membrane that forms the peaked roof of the terminal at Denver International Airport. A pedestrian bridge was built at the north end of the train terminal to allow access to platforms and adjacent development.

A new light rail facility, with three tracks and a station, has already been built on the west side of the transit site, next to the bus facility. It opened in 2011.

In addition to water contamination, other environmental issues on the transit project included the removal of asbestos and coal dust. Contractors found coal dust, from old trains fueled by coal, 12 ft down, according to contractors. They also stumbled onto old baggage and service tunnels, water and sewer lines, and even bones—which turned out to be cow remains. Some of those discoveries were surprises because there were no surviving plans or maps of the original train yard, which dates back to the 1870s.

“The biggest take-away from this project is that it proves that cities can deliver significant infrastructure projects that are also about creating a new neighborhood,” says SOM’s Takacs. “And they can do that through public-private partnerships.”