As crews put the finishing touches on the rebuilt $13 million Fillmore Street and Interstate 25 interchange, the city is gearing up for another major road construction project less than a mile west of there.
The extension of Centennial Boulevard south to Fontanero Street, which will navigate hilly terrain in a landslide-susceptible area, is in the design stage in the run-up to bid-letting late this year or in early 2017.
"We have a geotechnical engineer on board," says Aaron Egbert, city Public Works Department senior engineer working on the project. "They have provided us with a geotechnical report. That report will detail any issues or concerns they have and potential mitigation requirements."
At the same time, some residents have expressed concern about how wildlife will be affected by the four-lane road in an as-yet-undisturbed area. Among those is Gail Black, who notes in an email to the Independent that the road will skirt a bird sanctuary and disrupt habitat for a variety of wildlife, including deer, rabbits, beavers, coyotes, foxes and bears.
Centennial's extension has been in the city's long-range transportation plan since the 1980s, says traffic engineer Kathleen Krager. The project originally was given "C-list" status, or a low priority, on the Pikes Peak Rural Transportation Authority's original funding plan in 2005 and was never funded. But as development has picked up in that area, including construction of a veterans clinic at Fillmore and Centennial, the project has been pushed to the A-list, the city's website says.
Budgeted at $10.5 million in 2012, the project likely will cost more, Krager says, considering "we've had a pretty steep inflation rate on our projects in the last couple years." But additional costs shouldn't be a problem, she says, because PPRTA's tax revenue is also growing due to a rebounding economy. Much of the right-of-way for the road has been acquired, she says.
The city's website describes the project as passing through "highly variable topography" between Van Buren and Fontanero streets, which will require earthwork cuts and fill, as well as retaining walls. Design of other portions is underway.
To deal with the hilly terrain, Krager says, the city will build the northbound side higher than the southbound side. The road will reach grades up to 6 percent, Egbert says; in comparison, the grade of westbound Fillmore from Interstate 25 is about 9 percent.
The new road is expected to carry about 17,000 vehicles a day, Krager says, roughly the volume of traffic on North Nevada Avenue south of Fillmore.
The road will relieve pressure on the I-25/Fillmore interchange, notorious for backups to the east and west, although Krager says the new interchange will eliminate delays once the project is completed this summer.
Besides easing vehicular traffic at the interchange, the new stretch of Centennial will offer a new bike route from the northwest portion of the city, including Mountain Shadows subdivision, to the downtown area. The new road will be marked with bike lanes, and cyclists will be able to connect with the Legacy Loop in Monument Valley Park at Fontanero. The Legacy Loop is a trail that eventually will encircle the city's core area.
The area where Centennial will extend for 1.5 miles south of Fillmore includes "steep slopes along the margins of the mesas [that] are prone to mass wasting processes, such as landsliding," according to the Colorado Geological Survey's Division of Minerals and Geology.
Aware of this, Egbert says the city will take the necessary steps to assure the road holds up. "It's in a landslide susceptible zone," he notes, "but it is not in any known landslide area based on documentation that we have. There are some known landslides adjacent to the roadway but not where the roadway is."
To create a stable road base, Egbert says, the city could remove expansive clays and soils and replace them with stable materials beneath a road base of gravel and asphalt. The city is unsure what type of mitigation, if any, would be needed, because design is only 30 percent finished. "That's a detail we'll dive into as we go into final design — how deep to dig to replace materials," he says.
It's not the first time roads have posed a problem due to landslide potential. In the late 1990s, a 700-foot stretch of Broadmoor Bluffs Drive on the city's southwest side sank by 8 inches due to failure to account for that factor. After a protracted legal action, the city settled with the developer in 2007 for $1.5 million and fixed the road by driving 37 caissons, 5 feet in diameter, 80 feet deep to create an underground retaining wall.
Meantime, Black is concerned the road will disrupt wildlife habitat and wonders if the road is essential. "We humans need to back off a bit," she says in an email to the Indy. "It's okay to be a little 'inconvenienced.' We don't always need to have our way. We need to increase our efforts to let other life forms take the front seat for a change."
City officials are aware of neighbors' concerns about the habitat and open areas. "We're trying to be very sensitive to that," Krager says, "to make sure there are neighborhood connections to the green areas, to make sure we're not hurting environmentally any of the drainage area."
But Egbert notes there are no endangered species in that vicinity to prevent development. He also notes the city might include deer-crossing signs as part of the project's signage.
He says property adjacent to the Centennial extension could be developed for apartments, a church, senior living community and mixed use, such as offices and retail.
The new road is expected to open to traffic in late 2018.