Transportation officials have been busy trying to undo the knot that is rush-hour gridlock on Interstate 25 south of Denver by testing a tech-heavy and precision-based traffic management approach — and the results are in.

With CDOT’s coordinated ramp metering system in full operation, afternoon commuters saved 2.5 minutes on average in travel time driving the 14 miles from Ridgegate Parkway in Lone Tree to University Boulevard in Denver. That was a 14.3% improvement over the time spent traversing that stretch of I-25 before the technology was turned on.

The difference was even sharper during the heaviest hour of the evening commute, with drivers cutting off more than four minutes in travel time between Douglas County and Denver — a 19% improvement in travel time from before the Smart 25 Managed Motorways Pilot Program launched last year.

Morning rush-hour results were less impressive, with an average 2% time savings for commuters during the a.m. peak compared to pre-pilot conditions.

The pilot ran last spring and summer on the northbound lanes of I-25 and officials at the Colorado Department of Transportation have been interpreting the results since.

“These systems have the ability to greatly increase the efficiency of highway networks,” said Ben Kiene, a traffic operations engineer with CDOT. “There’s less stop and go. You’ll slow down but speeds recover.”

Now the trick is making the technology — which uses real-time software algorithms to precisely control the intervals at which vehicles enter the interstate from on-ramps down to fractions of a second — permanent and more widespread.

“There was enough there that we want to explore expanding further,” said Angie Drumm, CDOT’s metro Denver deputy director of traffic and safety. “In order to expand it, it would require investment in the detectors and controllers that control our ramp metering.”

But that requires money. CDOT is applying for a $1.5 million federal grant that could allow it to plan for an even bigger implementation of the coordinated ramp metering technology — possibly all the way from Lone Tree up to Thornton.

It’s a $50 to $60 million proposition but the payoff in travel time savings could be huge, Kiene said. That’s because the efficiency of traffic flow from the constant and minute manipulation of the time cars wait on entrance ramps before merging onto the highway is amplified as more ramps are incorporated and more data about conditions down the road are folded into the system.

“If we were able to implement this across a much larger system, you could have really significant results,” he said.

That was proven in Melbourne, Australia, where the coordinated ramp metering approach was applied across a much wider area than 14 miles of Denver’s southern suburbs. The results gathered on the M1 freeway were impressive: The number of vehicles getting through increased by 25% during peak commuting periods, travel speeds improved 35% to 60% during peaks and crashes went down by 20% to 50%.

Justin Schmitz, director of public works and mobility for Lone Tree, praised the pilot program for improving traffic conditions on I-25 last year. As to whether tighter control of vehicle movements on on-ramps bled over to increased stacking on the city’s streets near interchanges, Schmitz said that was a problem the city had to deal with.

“The most significant area impacted was on northbound RidgeGate Parkway,” he said. “The project team worked throughout the pilot to improve queueing conditions to minimize the impact of that spillover.”

But with growth in the southern tier of the metro area continuing at a robust pace, Schmitz said CDOT has to try what it can to improve the flow of traffic.

“Continuing to invest in smart technology such as the metering technology on the I-25 corridor is critical as density in this part of Colorado increases,” he said. “Working to improve travel experiences in and around the City of Lone Tree aligns with our organizational goals as well.”

CDOT’s Drumm agreed, saying there is no immediate prospect of widening the heavily traveled roadway through the Denver Tech Center.

“Expanding capacity is not in our 10-year plan,” she said. “This is one way we could help.”

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