The I-225 Rail Line under construction through the Denver suburb of Aurora is a key piece of the region's mass transit infrastructure—and a long-awaited link between the metro area's growing southeastern suburbs and Denver International Airport, one of the world's busiest hubs.

The 10.5-mile light rail line, dubbed the Aurora Line by the city, will connect the Regional Transportation District's (RTD) largely completed Southeast light rail line and its East commuter rail, scheduled to be finished in 2016. The eastern line originates in downtown Denver and will run to the airport. The I-225 rail project—its complete tab estimated at around $690 million, with $355 million in construction costs—is also slated to open in 2016.

"The connectivity of this project is very important," says Robert Kennah, design project manager for AECOM on the I-225 Rail Line. "From a big-picture standpoint, there's the connection to the airport and Nine Mile Station and what it does for Aurora and the Fitzsimons medical campus. That's what this project is about."

The city of Aurora is also anticipating the transit-oriented development (TOD)—from apartments to retail and office space—planned near rail stations and the impact the line will have in attracting younger workers.

"This project gives the city an opportunity to appeal to millennials," says John Fernandez, team leader for the FasTracks/TOD team in Aurora's planning and development department. "The whole metro area is attractive to 20-somethings, and being part of a regional mass transit system allows Aurora to compete better economically."

Crown Jewel

The I-225 Rail Line is part of RTD's multibillion-dollar FasTracks program, approved by voters in 2004 to expand the region's increasingly sustainable mass transit system by adding rail and rapid-transit bus service, transit stations, park-and-rides and some 21,000 parking spaces. The program's crown jewel is downtown Denver's historic Union Station, which has been redeveloped as a multimodal transportation hub for the metro area.

The I-225 line will mostly parallel Interstate 225 but also run for a stretch along Aurora city streets near the central hub of government buildings, shopping centers and residential neighborhoods. The rail will serve the hospitals, labs and educational facilities at the roughly 600-acre Fitzsimons Life Science District and Anschutz Medical Campus.

The main project components, in addition to the rail, include eight rail stations with platforms and canopies; 1,800 parking spaces; seven bridges, including a prefab steel pedestrian span over I-225; and seven at-grade crossings. Underground work ranges from relocating utilities to installing rail-signal systems.

One of the project's major components involves rerouting traffic while rail lines are under construction down the middle of Aurora streets as well as coordinating train and street traffic once that part of the line is operational.

"I don't know of another area with a two-way train operating on two-way streets," says Fernandez. "That's why RTD has scheduled burn-in time for train drivers to get used to the traffic system."

P3 Design-Build

General contractor Kiewit Infrastructure Co. jump-started the project by being willing not only to build the rail line but also to help finance it. Because of the economic recession that started in 2008, the I-225 line had been in a holding pattern for lack of funding. In early 2012, Kiewit—which was already working on the Denver Union Station project with AECOM—submitted an unsolicited proposal to RTD for the Aurora Rail Line as a design-build project for nearly $350 million, including financing via partner RBC Capital Markets. RTD is repaying construction costs from the sale of bonds, to be repaid through existing sales-tax revenue.

"Before Kiewit came in, we were looking at getting the project done a long way out—in 2020 or 2035," says Chuck Culig, a civil engineer and RTD's I-225 Rail Line project manager. "It was going to take that long to finish. We had 30% pre-done engineering drawings to give Kiewit, and because this is a design-build project, they started construction in multiple places."