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Inventor says synchronized lights could boost Green Line travel time

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A Green Line train
A Green Line train goes down University Avenue in St. Paul.
Will Matsuda / MPR News

Nick Musachio has heard the frequent complaints that the Green Line halts too often at traffic intersections, making for long commutes.

A local inventor from St. Paul, he has a solution, one that would have the trains riding between St. Paul and Minneapolis cruise through a wave of green lights.

Currently, stoplights play a fluid role, where pedestrian walk buttons, the volume and direction of traffic and other factors extend and cut short green and red lights.

At a handful of intersections along the Green Line, a newly implemented system gives trains priority over oncoming traffic at stoplights.

• May 2014: Green Line schedule lowering travel time

With last week's addition of "predictive priority" at Mackubin Street and Western Avenue - on top of initial sites at Chatsworth, Victoria and Grotto Streets — Green Line trains have rolled without stopping through those intersections at an "almost universal" rate, Metro Transit General Manager Brian Lamb said.

Musachio, holder of nine transportation patents and president of Kefty, a home gym company, is calling for a paradigm shift. Instead of altering stoplights to match the light rail's pace, his "Always Green Traffic Control" system instead would guide drivers' behavior.

Musachio is proposing timing traffic lights on certain sections of the line so that they operate on a tight, fixed cycle — simultaneously lighting entire patches of University Avenue green.

Dynamic, real-time panels placed up to a half mile away from intersections would calculate and provide drivers of cars and trains alike the speed at which they need to continue to make the light "wave" and cruise without pause for many blocks.

"You can either change the lights to match the vehicles," said David Levinson, a civil engineering professor at the University of Minnesota. "Or you can change the vehicles to match the lights."

Levinson said keeping cars moving at a steady speed is optimal for traffic flow. But he said it takes a lot of coordination and a tightly-maintained fixed traffic system to create a grid of alternating, forward-moving platoons of cars and trains.

Nancy Homans, policy director for Mayor Chris Coleman, said the city's public works department has discussed "Always Green" with Musachio. Lamb said municipal authorities, not Metro Transit, will make the final call whether or not to implement a new fixed traffic system.

John Hourdos, the director of the University of Minnesota's Traffic Observatory, has some reservations. He said while the concept of fixed traffic signals paired with real-time road signs is straight forward and relatively easy to install, it could be most successful applied only to isolated intersections.

When entire traffic systems are rigid and synchronized down to the minute, Hourdos said, weather, pedestrians and other variables can easily throw them out of sync.

"In a very dense, urban environment," he said, "every small perturbation — a pedestrian stepping on the road, a bicyclist blocking your way for a few seconds, anything — can throw it off."

He said while Musachio's invention could smooth the light rail's 23-stop voyage, it would be more useful for cutting down on the stop and start times of trains and cars, not necessarily for boosting their average travel speed across "the most difficult network in the city."

"It's not going to improve travel time by much," he said. "We're talking seconds — maybe minutes."

Lamb said Metro Transit already is making progress on cutting the average travel time for end-to-end trips, which he said now fluctuates between 40 and 50 minutes.

"I take the Green Line almost daily," Lamb said, "and I can tell you from my observations as well as the data, it is definitely tightening up and we are making a lot fewer stops."

Other cities — among them Washington D.C. and Denver — operate fixed traffic systems, though Musachio's 2012 patent means no other place in the United States couples them with giant roadway signs to advise drivers on their optimum speed.

Musachio, who plans to meet with local transportation officials in upcoming weeks, believes "Always Green" is simple enough to be introduced in the Twin Cities quickly.

"The technology is not difficult, the technology is on the shelf," he said. "These could be on the street next year."

Editor's note: An earlier version of this story misquoted Musachio. He said the technology could be ready next year, not next week.