The blue, yellow and red lines indicate the construction focus points on California and 15th streets in downtown Denver.  

They signify something else — what’s below them are unknown.

“We don’t necessarily know what lies underneath,” Regional Transportation District CEO and General Manager Debra Johnson told reporters as she walked over 15th street’s dotted lines.

Johnson and other transportation officials on Monday described the uncertainty workers face as they figure out what lies beneath some of the aging, 30-year-old RTD light rail tracks needing replacement this summer.

The four-phase, $152 million project to replace the light rail track of the downtown’s business district loop begins Sunday with its closure, which will last until at least mid-September, barring any unexpected issues, according to RTD officials.

The RTD construction will shut down the D line, H line and the L line service to downtown stations, where officials plan to rip out light rail track and replace it. In the meantime, those lines will all detour to Union Station before entering downtown.

The key phrase is barring unexpected issues.  

Johnson, in fact, cited similar issues that delayed and increased costs for the ongoing 16th Street Mall reconstruction project. During the early stages of that project, workers unexpectedly found old pipes underneath the ground that ballooned the costs from $149 million to $172 million.

Those pipes were found only blocks away from the intersections targeted for reconstruction this summer.

Yet even if no unexpected issues show up, RTD’s downtown light rail reconstruction will already mean further road closures, traffic delays and temporary impacts to the rail and bus lines at a time when the 16th Street Mall corridor is already struggling due to the massive infrastructure upgrade project underway there.

‘The precipice of change’

The light rail track reconstruction is a first-of-its kind type of project for the public transit authority, officials said.

“RTD is a newer transit agency and we now are on the precipice of change,” Johnson said.

RTD officials said it is doing a full-depth reconstruction of the Downtown Loop, which first began service in 1994, with a goal of improving safety and mobility, replacing aging infrastructure and extending the life of the light rail network.

The initial phase will focus on five segments of “at-grade rail” and intersections in the downtown loop.

The intersections being reconstructed in Phase One are:

• California and 17th streets

• Stout and 15th streets

• Stout and 17th streets

• California and 15th streets

• Broadway and Welton Street

The next phases will focus on midblock reconstruction on Colfax Avenue and the Welton Street corridor.

Officials underscored that reconstruction is a natural product of growth.  

“If you’re going to grow, and you’re going to develop and you’re going to improve what you have, you do have to take the time to have some construction that makes it all possible,” RTD Board Member Doug Tisdale told The Denver Gazette.

“There are 30 buildings over 30 feet in height that are under construction in Denver. It’s a happening place. And we’re bringing that same kind of energy back now,” he said.

Insofar as the impact to businesses, Johnson said, “We’ve been able to engage with the businesses and with the city and county.”

Meanwhile, business groups said they’re in close communications with city officials about the downtown projects and relaying what they’ve learned to their members.   

“VISIT DENVER is communicating the transit changes to groups meeting in Denver and to visitors via our website as well as to all downtown hotels,” a Visit Denver spokesperson told The Denver Gazette. “We are doing so in close communications with Denver Office of Transportation and Infrastructure (DOTI) and the Downtown Denver Partnership (DDP).”

“We know DDP and the City have grants available for downtown businesses … impacted by the rail construction project,” the spokesperson said, adding, “While we understand there will be impacts to the light rail lines through downtown, visitors will still be able to take transit to Denver Union Station and have access to the MallRide and the reinstated MetroRide, both of which are free.”

Preparing for closures

RTD said it plans to pause after the first phase is complete and resume with the following three phases in 2025 — and that work may happen simultaneously.

RTD officials said they don’t plan to reconstruct the five intersections simultaneously, so traffic impacts would be staggered.

Traffic in the area would be merged to one lane or rerouted around construction for limited periods of time during the summer, the officials said, adding that routes that travel up and down 15th and 17th streets could see temporary impacts during the improvement projects.

Transit officials said they plan to limit detours in the area as much as possible, and that RTD plans to temporarily reintroduce its Free MetroRide service up and down 18th and 19th streets.

“Both the Free MallRide and MetroRide routes provide multiple stops between Denver Union Station and Civic Center Station,” officials previously said.

“There can be an instance where (reconstruction) could be more expeditious or it could take a little while longer,” Johnson said. “What we’re going to do is communicate out very efficiently and effectively relative to any hiccups we may encounter along the way.”

Reporters Scott Weiser and Bernadette Berdychowski contributed to this report.