Crews excavate underneath the bridge to widen the lane.
By June drivers traveling through the southern Denver metropolitan area, near the suburb of Centennial, will enjoy the results of improvements to one of the area’s peskier interchanges.
The intersection at Interstate 25 and East Arapahoe Road, a major east-west commuter route, has grown busier and busier over the years. In a move to increase capacity, the Colorado Department of Transportation (CDOT) is adding an additional through lane in each direction to Arapahoe Road where it passes underneath I-25.
“This is basically a stopgap job to get us three lanes until we can get enough money to re-do that whole bridge,” stated Ed Bullard, project engineer for CDOT’s Denver metropolitan region.
In addition to the new through lanes, the project includes a dedicated turn lane from westbound Arapahoe Road to northbound Yosemite Street and improves left turn movement from southbound I-25 to eastbound Arapahoe Road.
The $2.4 million contract was awarded to Structures Inc. (Approximately 60 percent of the Denver-based company’s work volume, which totals about $20 million per year, consists of projects for CDOT.) Structures Inc. began construction in late September. By the end of January, the project was approximately 40 percent finished, and has a scheduled completion date of mid-June or earlier.
To date, the project has gone smoothly. “So far, so good,” said Bullard. “Over the last couple of months, weather has been a little bit of an issue, but now that things are starting to warm up a little we hope to get things to accelerate.”
Tony Bruski, project manager at Structures Inc., agrees that working through the winter has its challenges. Another object to overcome was Structures Inc. having to re-phase the project at least three times in order to keep working while waiting for the utilities to be relocated. All together, utility relocation was delayed by nearly four months.
Now, crews are finally finishing up underground utility work. They also are excavating under the bridge, in order to gain the 20 ft. (6 m) needed for the expansion of the new westbound through lane. Structures Inc. used the Bobcat 442 with a 1,500 lbs. (680 kg) hammer to demolish 80 percent of the original retaining wall, which was 220 ft. (67 m) long and 12 ft. (3.7 m) tall, on average. Once down to the wall’s foundation, they were able to bring in a 320 excavator, with a rented 2,500 lbs. (1,134 kg) hammer, to complete the demolition.
“We were using such a small piece of equipment [for the first phase of demolition] due to the horizontal clearance between the traffic and the wall; there was eight feet between the traffic and the wall,” said Bruski.
The new retaining wall is a soil nail wall with a 7-in. (17.8 cm) concrete fascia for decorative purposes. After it is finished, the contractor will be able to add the new through lane.
To create the eastbound through lane, crews are taking out the median between two existing ramp lanes and doing some repaving to turn one ramp lane into a through lane. “That one we can do without having to move too much dirt,” said Bullard.
Subcontractors are local companies such as American Infrastructure Inc. (underground utility installation), Standard Electric Co. and Taylor’s Landscaping LLC.
The improvements to the Arapahoe Road/I-25 interchange are funded by money remaining from the Southeast Corridor Transportation Expansion Project (T-REX), the largest transportation contract in Colorado history. The $1.16-billion T-REX project took place from 2001 to 2006.