'Seriously bad engineering': Stop lights slow Green Line - Bring Me The News

'Seriously bad engineering': Stop lights slow Green Line

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By some measures, the new Green Line has been a real success since its June 16 launch – ridership is higher than expected and crime has been low. Riders seem to like it.

But a persistent criticism lingers: The train is too slow.

A forecasted end-to-end travel time of 49 minutes between the downtowns of St. Paul and Minneapolis in reality sometimes takes more than an hour, and averages about 53 minutes, Metro Transit officials told the Pioneer Press. An early forecast had been just 40 minutes, the newspaper reports.

A big reason for the delays: stop lights. Trains currently roll to a stop when traffic lights are red. They do not have "pre-emption" — the ability of approaching trains to always trigger a light to change to green, the Star Tribune reports.

That would likely slow traffic, but shorten train travel times along the 23-station, 11-mile route.

It's "seriously bad engineering" to have trains waiting so much at lights, transportation expert David Levinson told the Star Tribune. Metro Transit General Manager Brian Lamb acknowledges to the Pioneer Press, "It is hard to rationalize a train with 300 people stopping at an intersection with no cross traffic."

But in consideration of pedestrians and traffic, St. Paul city officials are not eager to allow the Green Line to automatically trigger green lights on the route's 46 intersections with signals, even at the 19 with "low-volume" cross-traffic.

Still, St. Paul officials say they've been modifying the signal system and expect to make more improvements, the Pioneer Press notes.

The Pioneer Press also explains the concept of "green bands" sensors that trigger a few seconds of a new green light, or an extended green light, at some intersections, designed to give trains a better chance to sail through. It doesn't always work. But getting more trains through the green bands is an ongoing project for city officials in St. Paul, the Pioneer Press reports.

There's a lot at stake. Delays have made it difficult to coordinate departure times with Blue Line trains, which share five stations with the Green Line. Eventually, officials will want to coordinate with the southwest light rail train, too.

Aaron Isaacs, a retired longtime Metro Transit official who writes for the site Street.mn, told the Pioneer Press that the Green Line's reliability is in real question, which could decrease ridership.

Isaacs advocates pre-emption for all low-volume intersections. "There are simply too many traffic lights spaced too close together for conventional signal timing ... to move the trains along," Isaacs writes.

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