T-REX Transportation Expansion Project, Denver, CO, USA

The T-REX Transportation Expansion Project (previously known as the Southeast Corridor Project) is a $1.67 billion venture that is designed to revolutionise the transportation network in and around Denver, Colorado. The project comprises several components including 17 miles of highway expansion and improvements to Interstate 25 from Logan Street in Denver to Lincoln Avenue in Douglas County and Interstate 225 from Parker Road in Aurora to a newly configured I25/I225 interchange as well as 19 miles of light rail developments along these routes, a new drainage system and improved pedestrian and bicycle access. The highway aspects of the project account for $795 million of the total budget.

I-25 is the only North-South Interstate in Colorado and, along the T-REX project corridor, links two high employment areas, Downtown Denver and the Denver Tech Center. An average of 162,800 vehicles a day pass through the I-25/I-225 interchange and both highways are constantly congested during daylight hours.

T-REX is a collaboration between CDOT, the Regional Transportation District (RTD), the Federal Highway Administration (FHWA) and the Federal Transit Administration (FTA) and construction will run from Summer 2001 to Fall 2006. An integrated management team, called the T-REX Team, composed of personnel from CDOT, RTD and Carter & Burgess, Inc., was responsible for the procurement of the design-build team and will manage the implementation of the contract. The entire T-REX project is being run as a single design-build contract which was awarded to Southeast Corridor Constructors, a group led by Kiewit Construction Co. and Parsons Transportation Group.

INTERSTATE 25 HIGHWAY IMPROVEMENTS

There will be four through lanes of traffic in each direction between Logan and the I-25/I-225 Interchange, and five through lanes of traffic in each direction between the interchange and C-470/E-470.

Bridge replacement and reconstruction will take place along I-25. The following bridges will be replaced: Logan Street; Washington Street; Louisiana Avenue; Emerson Street; Downing Street; Franklin Street; Steele Street; University Boulevard; Evans Avenue; Quincy Avenue. The following bridges will be reconstructed (which includes widening and/or other improvements): Colorado Boulevard; Highline Canal/Bike Path; Belleview Avenue; Orchard Road; Arapahoe Road; Dry Creek Road; County Line Road.

INTERSTATE 225 HIGHWAY IMPROVEMENTS

A portion of Interstate 225 is to be upgraded to a three-lane highway as part of the T-REX project. As with Interstate 25, acceleration/deceleration lanes will be introduced and shoulders widened where feasible. Also, the southbound bridge over Cherry Creek will be replaced.

INTERSTATE 25 AND 225 INTERCHANGE RECONSTRUCTION

The redesigned and constructed interchange between the two highways will provide a much smoother junction. All of the left-hand exits and entrances will be reconfigured as right-hand exits. For example, vehicles exiting Interstate 225 onto the southbound I-25 will merge from the right instead of the left. DTC Boulevard slip ramps will be added both to and from Interstate 225.

STORM WATER RUN-OFF DRAINAGE SYSTEM

The existing storm water drainage system along Interstate 25 will be replaced. In the Narrows section (between Broadway and University) a new storm sewer will direct water to the South Platte River west of the interchange. Another storm sewer may be constructed on Buchtel Boulevard. Most of the existing storm sewer in the median of I-225 from the I-25 interchange north to Parker Road will be relocated under the northbound shoulder of I-225 to accommodate the light rail line. The cost to replace the existing drainage system is estimated at $40 million for the entire 19-mile project. More than half of that, $21 million, will be used to replace the storm sewer system in the Narrows area.