Wye Not? | streets.mn

Imagine arriving at the Mall of America light rail station and seeing trains for both downtown Minneapolis and downtown St. Paul, and not waiting 20 years until the Riverview Corridor is built.

When the Hiawatha Line (today’s Blue Line) opened in 2004, it had service every 7.5 minutes (8 trains per hour). [As of this writing, Wikipedia still thinks it does]. Today it has service every 10 minutes (6 trains per hour). In exchange service was transformed from to 3 car instead of 2 car trains. Most transit riders I know would prefer the more frequent service. (Most auto users of course prefer fewer trains, as that means less problems at traffic signals.)

Engineering sketch of Cedar-Riverside Wye Junction.

When the Central Corridor (today’s Green Line) was proposed, it was to have “16 trains per hour“, i.e. service every 7.5 minutes in each direction. Today it has service every 10 minutes. The bottleneck, we are told, is downtown Minneapolis, where the lines come together, providing train service every 5 minutes.

However most users of the Green and Blue Lines are not going downtown. Many are going to other destinations along the line. That is what keeps them in business. In fact, many riders transfer from the Green Line to the Blue Line (and vice versa) at Downtown East.

Suppose in addition to today’s service MetroTransit provided one more service, let’s call it the Cyan Line*, running from St. Paul to Bloomington, requiring very little additional construction, and no additional train cars (if we are willing to reduce the number of cars per train), that did not further congest the critical points in downtown Minneapolis.

MetroTransit could add about 3 trains per hour (one more train every 20 minutes) with no additional cars if each train went from 3 car to 2 car length, for a total of nine trains per hour (9*2 = 6*3). Alternatively, they could just buy more cars. (To achieve the “High-Frequency Network” designation, there would need to be 4 trains per hour in each direction, though since the lines already have service, I am not sure this is required).

To achieve this, MetroTransit would need to construct the small section illustrated in the figure (map). This Wye Junction would take very little land in Currie Park, and quite possibly no buildings. Some park land would need to be replaced. (I see some nearby surface parking that would be suitable, if not land bridges/interstate lids/freeway caps.)

What the Cyan Line service (shown in figure 2) achieves is not so much direct access from St. Paul to Bloomington, which would be a very long trip (on the order of an hour), but direct access for other Green Line origins (destinations) like the University of Minnesota to Blue Line destinations (origins) like South Minneapolis, the Airport, and the Mall of America.

Metro Transit Diagram with Cyan Line added

Shorter distance trips on the same line (e.g. from Lake Street to the VA, from Snelling Avenue to downtown St. Paul) would also see increased service. Once eastbound on the Green Line at West Bank, it changes from Cyan to Green Line designation since they share a common destination. Once southbound on the Blue Line it changes from Cyan to Blue Line designation .**

As we know, transit is a positive feedback system. Cut back the service, and ridership drops. Lose more riders, cut more service. This works in both directions. Add service, ridership increases. Ridership increases justify more service. Over the long run, land use patterns change.

How much will this cost? I don’t know, but this is in practice a really short section, I am guessing on the order of $10 million in initial construction. Additional costs for trainsets and labor as needed.  The Minneapolis-St. Paul region needs to be more creative about the services provided. I am suggesting build the Wye and run 3 Cyan Line trains per hour for a few years. If it works, expand it. If in fact long distance trips from Bloomington to St. Paul are using it, it provides justification for the Riverview Corridor. With a Riverview Corridor, the Cyan Line could be extended along that new track (with additional Wyes where the Riverview meets the Green and Blue lines, respectively), and be transformed into a Circle (or in this case, Triangular) Line.  If not, the region has lost very little.





* Many of the more common colors are spoken for, Cyan is the mixture of Blue and Green.

** Granted stopping at both West Bank station and at Cedar-Riverside Station is not ideal, it is no worse than what happens at much less used stations in Bloomington.


Cross-posted from streets.mn

One thought on “Wye Not? | streets.mn

  1. What are the numbers for the demand for the transfer from the Green Line to the Blue Line? Is the transit demand enough to cover the cost of building the other leg of the wye junction and retrofitting the signalling system?

    Likely, a cheaper solution would to coordinate the scheduled times of the two lines to allow for an immediate cross-platform transfer at Downtown East station.


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