Mere yards from its intended station stop, an eastbound Green Line train rolls to a halt before the traffic signal at Dale Street and University Avenue, waiting for the red light to change.

It’s a frustrating scenario that is repeated time and again along the St. Paul portion of Metro Transit’s new light-rail corridor. Rather than breeze through green lights as intended, trains have been bogged down at intersections with traffic signals, gradually losing precious minutes over the course of 11 miles and 23 stations.

The unintended stops have thrown the Green Line out of step with connecting bus services, interfered with Blue Line departures in Minneapolis and forced Metro Transit to add trains to its schedule, a potential long-term stress on its operating budget.

“The overall travel time and consistency is not where it should be on University Avenue,” Metro Transit General Manager Brian Lamb, said in a statement Friday. “It is hard to rationalize a train with 300 people stopping at an intersection with no cross traffic.”

Nevertheless, city officials in St. Paul remain reluctant to give the Green Line full authority to turn red lights green along 46 intersections with signals. They say that doing so, even at 19 low-volume crossings, would be to the detriment of pedestrians and cross-traffic.

“Ideally, we make everybody happy,” said City Engineer John Maczko. “Our desire as far as train operations is we’d (like to) be able to get from stop to stop without having to stop in between … (while) realizing there are other needs than just the train that the community has.”

A SLOW TRAIN?

The $957 million light-rail line was once expected to take riders from the Union Depot station in St. Paul to Target Field Station in Minneapolis within 40 minutes. Metro Transit’s printed schedules now list a travel time of 48 minutes. But actual trips since the line’s debut June 14 have averaged 53 minutes on weekdays, according to Metro Transit.

Each traffic signal represents either a chance to shave travel time or a potential stumbling block.

“The fine-tuning is taking longer than we had expected, but we are encouraged by steady progress week after week,” said Metro Transit spokesman John Siqveland.

Officials with the Metropolitan Council, the regional planning agency that oversees Metro Transit, say most passengers will use the line for intermediate stops, rather than riding the entire 11 miles end-to-end. The average customer trip spans three miles.

But Aaron Isaacs said he believes the delays are a bigger issue than officials have let on. Isaacs, a transit planner who spent 33 years with Metro Transit before retiring in 2006, has been writing about the Green Line’s traffic signal challenges on the urban planning blog Streets.mn.

“Public transit requires reliability, and if people perceive it as unreliable, they’ll be less likely to ride,” he said.

Besides throwing commuters off schedule and causing them to miss connecting buses, Green Line delays have interfered with the Blue Line, which shares five station stops in Minneapolis. The two routes have been unable to coordinate departures because of the Green Line’s erratic arrival times.

The delays also threaten to create scheduling complications for the proposed Southwest Light Rail Transit line, which would extend the Green Line from downtown Minneapolis to Eden Prairie. Reliable city-to-city transit connections remain an important selling point to federal funders and municipal leaders along the route.

Isaacs said St. Paul could easily speed up trip times by allowing Green Line trains to roll through low-volume intersections along University Avenue such as the crossings at Chatsworth, Fry, Hampden, Griggs and Grotto streets.

“There are 19 minor intersections that I think should go full preemption because there’s much, much smaller traffic volumes,” Isaacs said. “This is all on the city.”

While reluctant to embrace the idea, St. Paul officials say they’ve been modifying the signal system and expect to make more improvements.

“Everybody in this region is new to this operation,” said Maczko, the city engineer. “Met Council’s operators are learning and gaining experience. The traffic engineers are learning and gaining experience. And it’s a new system. It’s a constant work in progress to do that.”

Met Council officials say about 90 percent of the problems with the city’s traffic signal system have been resolved.

It remains to be seen whether the Green Line’s overall delays will affect the light rail’s estimated $35 million operating budget.

When trains or buses fall behind schedule, more are deployed. The additional costs build up over time. Metro Transit has been running 13 Green Line trains for most of the service day; 12 were originally originally planned.

“My overall sense is that travel times are improving, and there’s been good steps to enhance that,” said Jon Commers, one of St. Paul’s members on the Met Council. “But I think that we have more work to do.”

Meanwhile, the Green Line appears to be moving more smoothly through traffic signals in Minneapolis, especially on the University of Minnesota campus. Results in downtown Minneapolis, however, have been mixed.

“We’ve had the luxury of 10 years of experience with the Blue Line downtown, but there’s still a little tweaking,” said Jon Wertjes, director of traffic and parking services for Minneapolis.

HOW IT WORKS

In 2011, St. Paul upgraded the central control system that monitors two-thirds of the traffic signals within the city’s borders. Econolite’s Pyramid system was replaced with the company’s next “smartest” software, Econolite Centracs, at a cost of $260,000, with the expectation that new sensors beneath the light-rail track would inform the traffic signals that a train was on the approach or had just passed by.

Based on input from the sensors located anywhere from one to five blocks away, traffic signals are expected to extend, or switch to, a green light for a few seconds, allowing the trains to sail through. The extended window of opportunity at green lights is known as the “green band,” but not every train makes it within the band.

A pedestrian hitting a “walk” button shortly before the light rail crosses a sensor might still get to walk across University Avenue, putting the light rail on hold. A car turning in front of a train, or passengers boarding and exiting more slowly than expected, might also delay it from reaching a green light in time.

Meanwhile, video cameras monitor traffic on cross-streets, information that is also being fed to the traffic signals.

“If the signal has already made the decision that it’s serving the pedestrian or the vehicle on the cross-street, the (green light) won’t hold, because it’s already committed,” said Maczko.

Major crossings such as Rice Street, Dale Street and Snelling Avenue need to accommodate more traffic, so the “green band” window of opportunity for light-rail vehicles to cross a light is shorter than at a lower-volume intersection such as University and Griggs.

That said, getting light-rail vehicles through the green band remains an ongoing project throughout the entire St. Paul end of the system, and not at any intersection in particular, according to Paul St. Martin, traffic and lighting division manager for the city.

With the exceptions of the Rice Street, Robert Street and Raymond Avenue stops, the remaining 11 stations in St. Paul are located after an intersection and traffic signal, not before it. That creates the scenario where light-rail trains are having to stop twice — once at the light and immediately afterward at the actual station — without having full priority at signals.

Maczko said that putting stations before the traffic signals, though, would have eliminated turn-lanes from University Avenue onto those crossing streets.

WHY NOT FULL SIGNAL PRE-EMPTION?

Unlike along Hiawatha Avenue in Minneapolis, where the Blue Line debuted in 2004, the system does not give Green Line vehicles “full pre-emption,” or final say over traffic signals, and no crossing arms descend at intersections.

Maczko recalled heavy traffic backups on Hiawatha’s cross-streets during the first years of the route. “All the way to the early 2000s, it was decided … using pre-emption was not an option” on the Green Line, he said.

He pointed out that the Blue Line’s signal priority and crossing arms block everyone — pedestrians, bicycles, police cars and ambulances alike. University Avenue is more densely-populated, with a light rail running down the center of it, rather than to one side, and there’s greater need to accommodate a wider mix of uses.

And pedestrians have already made sacrifices. Before light rail, someone trying to get across University Avenue could do so every 660 feet. That has increased to every quarter-mile.

In some locations, walkers need to push a walk button because the lights no longer automatically accommodate them.

Some neighborhood advocates say they’d prefer to see a speedier train over faster cross-traffic. “The concept that these trains are stopping twice at each (station) intersection to accommodate the occasional car does not make sense at any level,” said Brian Quarstad, a member of the Union Park District Council.

City council member Russ Stark, a regular light rail rider, said he’s also noticed the Green Line stopped at signals with no cross-traffic. He’s confident that will improve with time.

“I don’t think there’s any emergency,” Stark said. “The majority of people on the train are happy about the way it’s going.”

Frederick Melo can be reached at 651-228-2172. Follow him at twitter.com/FrederickMelo.

BEATING EXPECTATIONS

After a month in operation, ridership on Metro Transit’s new Green Line continues to beat projections.

The average weekday ridership has totaled 30,264 passengers. Planners predicted it would carry 27,500 weekday riders in 2015. The numbers are considered preliminary until an official monthly audit is complete.

In 2013, daily weekday ridership on the Blue Line — which connects Minneapolis to the Mall of America in Bloomington — averaged 30,585 rides. The Blue Line began service in 2004.

Not including opening weekend when rides were free, the Green Line’s average weekend ridership is 24,269 rides. Those numbers were likely boosted by a free All-Star Week concert at TCF Bank Stadium.

— Frederick Melo