East Colfax Avenue will be the testing ground for a new type of transit system in Denver — one day.

The city’s plans for bus-rapid transit have been slowed significantly because Denver doesn’t have the money it needs to build the project, Denver officials said Thursday.

Originally the city hoped to start building within a few years but it now expects the project will take five to eight years to build — and it hasn’t said when that process will start. That means East Colfax BRT service wouldn’t begin until 2024 at the very earliest, and likely could be delayed into the late 2020s.

Denver voters approved $55 million in 2017 for the BRT system, which will create a separated lane for fast, regular bus service on the corridor. But the total cost may be more than $200 million, according to preliminary city estimates, and the city hasn’t secured the rest of the money. The final budget for the project hasn’t been determined.

Questions along the corridor have intensified in recent months, especially as East Colfax looms larger on the radar for private development and public investment.

“I need to know where that money is, where that project stands, and what comes next,” said Councilwoman Amanda Sawyer in an interview last month. “We can’t be planning an entire (East Denver) area plan around something that’s not going to happen. We need to have some specifics.”

City staff provided new information on the project in presentations and an interview with The Denver Post this week. The city’s budget took a blow when Colorado voters last year rejected Proposition 110, which could have provided $70 million for BRT in Denver, according to city spokesperson Nancy Kuhn.

The city will request federal grants to fill some of the gap, but it has only just started to explore that process.

“We’re leveraging the funding we have. And we’re developing a project description to determine what opportunities are the best fit,” Kuhn said.

Bus-rapid transit is meant to combine some benefits of rail — the vehicles can move freely in their own space — with the potentially lower cost of buses. The East Colfax BRT plan calls for closely packed stations that could transform Colfax into a walkable, transit-heavy corridor.

It could take five to eight years to win approvals and build the project, and that’s only after it enters a federal environmental review. It’s unclear when that countdown will begin.

Denver planners could shrink the project to reduce its cost, but the goal is to build out the full plan, Kuhn said. “I think the next step would be understanding what grants we’re going to go for,” she added.

Delays to BRT also will affect upgrades to pedestrian safety on East Colfax. Denver voters set aside $20 million to improve safety on the fast-moving corridor, but fixes on the eastern side of Colfax can’t precede the BRT work. The BRT system is slated to extend from Interstate 25 out to Yosemite Street.

Meanwhile, Denver Public Works is installing temporary fixes at a dozen intersections, including bollards and paint to “improve the pedestrian experience,” Kuhn said.