Transportation Expansion Project

Transportation Expansion (T-REX) Project
Company type	Public infrastructure project
Industry	Transportation infrastructure
Founded	1995
Fate	Completed
Headquarters	Denver, United States
Area served	Denver metropolitan area, Colorado
Products	Highway expansion, light rail transit

The Transportation Expansion (T-REX) Project represented a $1.67 billion effort aimed at improving transportation infrastructure within the Denver metropolitan area along Interstates 25 and 225, which was then ranked as the 14th busiest intersection nationwide. This initiative widened key interstate segments to accommodate up to five lanes in each direction and incorporated 19 miles of double-track light rail, culminating in extensive enhancements throughout the corridor. The project concluded 3.2% below its budget and was completed 22 months earlier than planned in 2006.

T-REX was one of the pioneering projects in the United States to implement a design-build contracting method, which consolidated engineering and construction responsibilities under a single contractor. While the agency outlined the overall framework, the contractor took charge of detailed design work during the execution phase.

This corridor currently handles daily traffic exceeding 280,000 vehicles and connects Denver’s two primary employment centers: Downtown Denver and the Denver Tech Center.

Funding

Because of TABOR legislation passed in 1992, T-REX could not rely on funding from state, county, city, or fuel taxes. Additionally, Colorado was hesitant to introduce new mandatory tax measures. Instead, voters within the metropolitan area approved property tax increases in November 1999 to help finance the transit portion of the project.

Primary financial components included:

A $1.18 billion design-build contract awarded to Southeast Corridor Constructors.
$879 million allocated for light rail development: $437 million sourced from RTD and local matching contributions; $525 million provided through a Federal Transit Administration full-funding grant agreement.
$795 million dedicated to highway improvements financed by highway user taxes combined with federal matching funds.
Acquisition of 34 new light-rail vehicles at a cost of $91.8 million.
$39.5 million invested in constructing the Elati Street Light Rail Maintenance Facility.

History

A traffic congestion analysis conducted in 1992 by the Denver Regional Council of Governments (DRCOG) revealed that traffic volumes on this corridor had already surpassed its designed capacity of 180,000 vehicles per day, predicting severe congestion within a few years. Projections indicated an additional 150,000 jobs would be created downtown and at the Denver Tech Center over two decades, leading planners to recommend both freeway expansions and integration of mass transit solutions.

In April 1995, the Colorado Department of Transportation (CDOT) joined forces with the Regional Transportation District (RTD) to establish T-REX. Together with DRCOG, they initiated the Southeast Corridor Major Investment Study (MIS) aimed at addressing congestion on I-25/I-225. Participation included Arapahoe and Douglas counties as well as cities such as Denver, Aurora, and Greenwood Village. Early MIS proposals emphasized transit-oriented strategies—such as light rail, highway upgrades, pedestrian and bicycle enhancements, Transportation Demand Management (TDM), Intelligent Transportation Systems (ITS), and safety improvements—without recommending additional highway lanes. However, the Federal Highway Administration and CDOT advocated for enhancing mobility through a balanced approach combining highway widening with transit improvements, which ultimately led to T-REX’s formation.

An expanded MIS completed in 1997 presented a more integrated plan featuring core highway expansions up to seven lanes per direction alongside comprehensive light rail coverage throughout the corridor. Additional input was provided by Lone Tree, Parker, and Centennial. DRCOG adopted this strategy that included 19 miles of double-track light rail with 13 stations running adjacent to I-25 and I-225.

In November 1998, DRCOG approved Metro Vision 2020—a two-decade regional transportation blueprint that prioritized T-REX. Planning activities commenced in June 1999 after legislation permitted CDOT to issue Transportation Revenue Anticipation Notes to borrow against anticipated federal funding. A Partnering Agreement was signed by CDOT, RTD, Federal Highway Administration, and Federal Transit Administration; meanwhile, voters endorsed light rail expansion along the corridor. Southeast Corridor Constructors—a joint venture between Kiewit Construction and Parsons Transportation Group—secured the design-build contract in May 2001; construction began in June that year.

The Partnering Agreement established four primary objectives: minimize community disruption by concentrating most work during nighttime hours; adhere strictly to a $1.67 billion budget; maintain high-quality standards; and complete construction by June 30, 2008. Oversight was provided by a Policy Committee responsible for public agency decisions and a Technical Committee managing planning, engineering, and environmental matters with input from local governments.

Throughout the NEPA process, these committees refined project alternatives aligned with Partnering Agreement goals using public meetings and workshops. In June 1998, all four agencies signed a partnering charter committing to multi-modal solutions. Public outreach efforts included milestone newsletters, media tours, informational displays at public venues, an updated website, and over 215 community forums.

By 2002, T-REX had acquired six single-family residences, two duplexes, two apartment complexes; negotiated acquisition of 30 full properties along with 172 partial acquisitions within a $100 million budget. Businesses received compensation covering replacement properties and relocation expenses.

This five-year design-build endeavor added 19 miles of light rail infrastructure while upgrading 17 miles of highway through southeast Denver and neighboring communities including Aurora, Greenwood Village, Centennial, and Lone Tree. Construction wrapped up in December 2006—22 months ahead of schedule—with light rail service launching later that same year.

Choice of light rail over HOV lanes

Light rail transit was selected because it minimizes disruption to homes, businesses, and sensitive areas such as wetlands and historic landmarks. It provides the greatest passenger capacity, fastest travel times, lowest cost per rider, enhanced opportunities for joint development, and superior reliability and safety. Furthermore, it garnered more robust public backing.

Denver Mayor John Hickenlooper supported light rail as a practical solution to congestion, emphasizing that expanding highway lanes often results in rapid filling by additional vehicles. The greater capacity of light rail enables it to accommodate growing traffic volumes without causing delays.

Timeline

April 1995 — Initiation of the Southeast Corridor Major Investment Study (MIS), which proposed a 19-mile light-rail extension with 13 stations and significant safety upgrades to I-25/I-225.
October 1997 — Denver Regional Council of Governments endorses the MIS.
March 1998 — Public hearings commence for the environmental impact statement (EIS).
November 1999 — Voters approve two bond measures to fund the project.
December 1999 — Final EIS is completed and signed.
March 2000 — Record of decision is issued.
July 2000 — Contractor prequalification for T-REX bidding begins.
November 2000 — Federal Transit Administration grants $525 million full-funding agreement; request for proposals issued.
May 2001 — Project rebranded as the Transportation Expansion Project (T-REX); Southeast Corridor Constructors (Kiewit-Parsons) chosen.
June 2001 — Contract awarded and notice to proceed given.
September 24, 2001 — Official groundbreaking ceremony held.
October 2001 — Construction activities commence.
March 27, 2004 — Partial implosion failure leads to demolition of bridges at I-225 and I-25.
April 2006 — RTD promotes T-REX project and announces opening date online.
July 2006 — Installation of station signage completed.
October 2006 — RTD offers reduced fares during inaugural week.
November 17, 2006 — Project officially completed and opened to the public.

Outcomes

The initiative is projected to conserve roughly of automotive fuel annually and reduce air pollution valued at about $4 million each year. By connecting I-25 with Denver’s two primary employment centers—downtown and the Denver Tech Center (DTC), together employing over 200,000 workers—commute durations have been shortened. According to the Denver Regional Council of Governments, regional expansion is expected to create an additional 150,000 jobs in these zones over the next two decades. Denver Mayor John Hickenlooper along with former Governor Bill Owens promoted the "Mission of Economic Development," encouraging businesses to relocate within areas developed by T-REX to improve workforce living standards.

Infrastructure achievements

Added one lane in each direction along most segments; two lanes added in heavily congested stretches.
Rebuilt eight interchanges at the I-25/I-225 junction, ranked as the nation’s 14th most congested interchange.
Completed reconstruction of the “Narrows” section between Broadway and Steele streets.
Replaced or refurbished a total of 18 bridges.
Installed acceleration and deceleration lanes throughout the corridor.
Expanded shoulders where possible.
Introduced Transportation Demand Management (TDM) strategies for optimized on-ramp signal timing.
Implemented Intelligent Transportation Systems (ITS) including ExpressToll electronic tolling for single-occupant vehicles utilizing HOV lanes.
Upgraded major drainage infrastructure.
Added of double-track light rail extending from Broadway in Denver to Lincoln Avenue in Douglas County along I-25’s west side, and within I-225’s median from I-25 to Parker Road in Aurora.
Established thirteen light rail stations with bus connections available at twelve locations.
Increased RTD’s light rail vehicle fleet by thirty-four units.
Constructed a new light rail maintenance facility located in Englewood.

On Interstate 25:

Added one through lane per direction from Logan Street to I-225, resulting in four lanes each way total.
Added two through lanes per direction from I-225 to the C470/E470 interchange, totaling five lanes each way.

On Interstate 225:

Added one through lane per direction between Parker Road in Aurora and I-25, providing three lanes each way overall.
Reconstructed and widened several bridges along this segment.
Enhanced drainage systems and upgraded safety features.
Improved shoulders alongside ramps as well as acceleration and deceleration lanes.

Similar projects

The Interstate 15 overhaul for the 2002 Winter Olympics in Salt Lake City, a collaborative initiative between UDOT and the Utah Transit Authority, provided a foundational example for the T-REX project. Although this effort integrated both light rail and highway improvements, Utah’s rail infrastructure did not run within the interstate's right-of-way.

During the planning of a comparable project along Phoenix’s Interstate 10 corridor, representatives from the Arizona Department of Transportation, Maricopa Association of Governments, and Valley Metro Rail examined T-REX’s approach. This initiative includes expanding the highway and adding new rail lines, with Valley Metro intending to place rail tracks within the highway right-of-way. While Phoenix’s light rail system was anticipated to be completed by approximately 2019, the highway upgrades were expected within a five-year timeframe. Additionally, the Wisconsin Department of Transportation has explored implementing design-build methods influenced by projects such as T-REX.

The success of T-REX is believed to have contributed to public support for the FasTracks initiative, which was approved in the 2004 election.

Reception

Overall public endorsement of T-REX remained strong despite resistance from some property owners impacted by land acquisition. Relocation assistance was provided with professional guidance, and community feedback resulted in slight modifications to light rail routing and station placement. Political support played a crucial role; Colorado Governor Roy Romer championed the project early on, and regional leaders backed light rail development, although certain politicians and interest groups opposed aspects of the highway expansion.

T-REX is widely recognized as one of the nation’s most effective transportation enhancement projects, having received numerous accolades including a National Design-Build Award from the Design-Build Institute of America.

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