Highway lanes and light-rail route will be added to the congested I-25 corridor. (Photo by Michael Goodman for ENR)

As Denver-area transportation officials debated how best to move people through the increasingly congested Interstate 25 corridor, mass transit advocates dug in their heels for a light-rail line. Highway advocates pressed for more lanes. The planners’ ultimate decision to fit a rail line into an expanded highway corridor accommodated both sides and thrust Denver into a two-pronged project that may be the example for others in the growing region.

Branded with Jurassic Park flair, the $1.67-billion design-build project dubbed "T-REX" (Transportation Expansion Project) is rolling along despite state budget woes that scaled back roadwork by $800 million and careless night drivers (ENR 10/29/ 01 p. 14). The smoothest part has been construction. Under the supervision of design-build veterans, the job is 50% complete and on schedule for completion two years ahead of the state Dept. of Transportation’s originally planned 2008 opening. It is founded on a multisource funding plan, coordination among scores of agencies and firms and a massive public outreach program.

Southeast Corridor Constructors, a joint venture of Peter Kiewit Sons’ Inc., Omaha, and Pasadena, Calif.-based Parsons Transportation Group, is expanding the 14-mile stretch of I-25 between downtown Denver and the Denver Tech Center to the south from six lanes to eight and 10. It cannot shut down lanes during the day. Another two lanes will be added to three miles of I-225 to the east. Overall, eight interchanges and 13 bridges will be refurbished.

On the transit side, the team is building 19 miles of double-track light rail and 13 stations. The rail will travel alongside the southbound I-25 lanes and down the I-225 median.

"This is the first time there’s been truly combined highway and transit at this level," says Randy Pierce, project manager for Carter & Burgess, Fort Worth, providing owner’s construction oversight for T-REX. Without design-build, which allowed for both fast-track work and bond funding, "this would take 20 years otherwise," he says.

Contractor’s Murphy, transit agency’s Clarke and CDOT’s Warner discuss job. (Photo by Michael Goodman for ENR)

Getting design-build legislation coincided with political support, funding and a grassroots effort in three counties and several cities. "We were blessed with good timing," says Larry Warner, T-REX project director. In 1999, voters approved two bond initiatives for the project. Gov. Bill Owens (R) signed a law that let the state borrow against anticipated federal funds and the legislature passed bills allowing CDOT to issue revenue anticipation notes for funding, design-build, increased private sector participation and landowner tax breaks.

No one questioned the need to expand capacity along the corridor, built for 180,000 daily vehicles and now carrying 230,000, says Warner. A C&B-led study concluded that both highway and light rail were warranted, and CDOT and the Regional Transportation District joined forces. Offering both "led to success on the environmental impact statement," says Warner. "There was little public comment."

Local jurisdictions pledged $30 million. The Federal Transit Administration contributed a $525-million Full Funding Grant Agreement in 2000 to the $879-million light-rail portion, with RTD and local matches funding the rest. The $795-million highway work is funded from existing highway taxes, bonds and federal money. Some 200 rights-of-way acquisitions have been done for less than the budgeted $100 million.

In 2001, SECC underbid its competitor by $186 million and pledged to finish the job 22 months earlier to boot. That suited project officials, who first researched other big design-build jobs such as Salt Lake City’s I-15 and New Jersey’s Hudson-Bergen light rail. "I-15 was successful in many ways," says Pierce. "We are trying to improve on that."

So are the I-15 veterans now working in Colorado. "We’re learning from past experiences and developing new controls and processes," says Bill Murphy, SECC project manager, who worked on both I-15 and California’s San Joaquin toll road for Kiewit and Parsons’ design-build joint ventures. For I-25, Parsons is an equity partner, he notes. "We’ve developed a mutual respect," Murphy says, which helps contractor and designer to address issues more swiftly.

More than 20 task forces for specific construction jobs, such as retaining walls, bridges or drainage, meet weekly as needed, with appropriate agencies and locals as members, says Jim Klemz, SECC design manager. Design moved swiftly, thanks to 5-day review turnarounds for submittals, he says. Now, design is complete and most of 320 designers from a team that includes HNTB, DMJM+Harris, Jacobs and 30 others have left.

Unlike I-15, where schedule topped all priorities, I-25 emphasizes minimizing public inconvenience, notes Murphy. But both priorities factor into the contract. Liquidated damages are assessed at a set cost for each lane mile, with amounts tied to different segments of highway and light rail. The maximum penalties for various segments are $50 million.

There are smaller fines for opening the highway late after overnight closures. SECC paid $24,000 in two cases where it reopened lanes late due to difficult bridge demolition, says Doug Brannan, SECC deputy construction manager.

An information campaign keeps drivers aware of changing lane closures and promotes safety. (Photo by Michael Goodman for ENR)

The contract includes an insurance program where the owner and contracting team will share what’s left over from about $9 million saved for such issues as claims and accident coverage. There have not been any worker deaths, but in April 2002, an improperly rigged crane setting barriers on I-25 just north of the I-225 interchange toppled onto the northbound lanes. Two cars were crushed and three people injured. Local subcontractor Front Range Barricade had subcontracted the work to Absolute Crane Service, which was suspended and paid a settlement of $4,500, says Occupational Safety and Health Administration spokesman Brad Baptiste.

Since then, a drunk motorist has crashed into a construction truck, injuring two workers and killing himself. Most accidents that account for the 20% increase in night-time accidents on T-REX are minor and attributable to driver error, says Barry Erlandson, SECC traffic control designer. "The biggest challenge is retraining the ‘familiar’ motorist," he says. "Commuters get on autopilot...they don’t read the signs."

Crews now check daily for blown-over signs and orange barrels, faulty striping and other issues, says Erlandson. "We brainstormed with local cops about reducing speeding," he says. That includes a media campaign with gas station signage, bumper stickers on project vehicles and increased patrols.

Daytime accidents decreased 3% last year. Klemz adds that detection monitors set up every one-third of a mile monitor traffic volume that is updated every minute to the project Website, www.trexproject.com. An incident review manual coordinated with 30 agencies helps guide a 5-minute response time for road incidents, notes Murphy.

"What we’re seeing is typical in any major construction project, and that’s an increase in minor traffic accidents," says Capt. John W. Lamb, Denver police traffic operations division. "On this project, [the roadway] is changing weekly."

Key to the fast schedule was swift mobilization. "We had 300 designers on board within a month" after winning the bid, notes Murphy. "We did a lot of scheduling up front." The team erected the site office within weeks, with CDOT and SECC employees separated by a floor. Crews work two nine-hour shifts, five days a week, and many summer Saturdays, says Brannan.

Contractor quality management includes "inspect and test" of specs, down to the tint of a precast panel. C&B’s Pierce adds that owner compliance auditors, teamed with Toronto-based Delcan, refer to a database of contract specs using hand-held computers with which they can file reports instantly.

Crews are drilling rows of up to 54-in.-dia caissons to depths of about 60 ft for 35-ft-high retaining walls along the Narrows, I-25’s northernmost four miles. Where needed, precast concrete panel noisewalls are erected, etched with images of local wildlife.

New 19-mile light-rail route includes flyovers, tunnels and 13 stations. (Photo by Gregg Gargan/Colorado DOT)

Along with nearly 200 utility relocations, the team revamped the Narrow’s drainage system. Designed to handle a 100-year flood, its components include a 13-ft-dia bored tunnel, several box culverts and basins, and collectors of 84-in. and 92-in.-dia pipe, says Brannan.

Work on the 6-mile southern segment calls for snaking the light-rail route through a five-level interchange with E-470, a toll road built to funnel traffic east of I-25, and toward Denver’s airport. required 25 retaining walls up to half a mile long and up to 20 ft high, says DMJM+Harris’s Bob Clevenger, segment design manager. There are no at-grade crossings between rail and road.

So far, some $40 million in change orders have been added to the job. CDOT asked SECC to rebuild two overpasses that had been contractually optional. The longest bridge is a new 2,000-ft-long steel girder span carrying traffic from I-25 to I-225. Bridges are either steel or precast concrete. David Evans and Associates Inc., Portland, Ore., used Cyrax laser-scanning technology to survey 24 bridges in 40 days.

Crews work day and night (Photo top left by Michael Goodman for ENR, right and bottom by Gregg Gargan/Colorado DOT)

The rail line includes seven flyovers, but SECC value-engineered two others into 300-ft-long cut-and-cover tunnels, saving about $2 million, says Rick Clarke, T-REX deputy project director. The design had called for bridges that soared 100 ft high over the I-25/I-225 interchange, and "we weren’t crazy about it," Clarke says. Crews now are beginning to lay 80-ft segments of track. Most steel is recycled from Denver’s old Mile High Stadium.

Work on all stations has begun. All have a 350-ft-long x 35-ft-wide platform and a canopy shelter. Design began before all land was acquired, but based on community demand, "we ended up customizing each one to create 13 distinct stations," says HNTB architect Doug Loveland. All but one have park-and ride lots. Three four-level precast concrete parking structures are also being built.

SECC Light Rail Manager Tim Mackin notes that new track paralleling I-25 in the northern segment will dip 25 ft into a trench for a major station below grade. Transit-oriented development is planned for the site. Siemens has a $90-million contract to build railcars powered by 750-volt overhead wires.

The local office of M.A. Mortenson Co. has a $32-million contract for a maintenance and control center. The system will connect to Denver’s downtown light rail and carry 33,000 riders, while highway capacity will increase by about 50%.

Pleased with the project, CDOT has begun an environmental impact study for a Denver-Boulder link that would emulate T-REX.