Even in an era of shrinking bus ridership, Metro Transit’s No. 21 bus carries 10,000 people a day, and is one of the backbones of the Twin Cities transit system. It’s the second-highest-ridership line in the entire system, a key link for the diverse, vibrant neighborhoods in central St. Paul and Minneapolis.

But in spite of all its utility, the No. 21 is neither efficient, fast, nor straightforward. It averages 8 miles per hour, about the speed of someone bicycling up the steep Marshall Avenue hill. On top of that, the route can be befuddling for new riders. For example, heading westbound out of St. Paul, the bus is simple: The No. 21 picks you up and heads down Marshall Avenue, crosses the river bridge, and heads (albeit slowly) down Lake Street to the north shore of Bde Maka Ska.

The return trip is not so simple: You can catch the No. 21A, the 21C, the 21E, or 21D, and depending on your odds, you might get where you’re going. The E branch stops short at Hiawatha Avenue; the C branch will take you to the corner of University and Snelling, and only the 21A goes “all the way” to downtown St. Paul along Selby Avenue. (The 21D on the other hand, ends at the corner of Summit Avenue and Finn Street, intended to serve St. Thomas students.) Get on the wrong bus, as I once did, and you can find yourself stranded very far indeed from your destination.

The asymmetrical complexity of the bus route offers a classic example of the importance of bus route legibility, and the sometimes maddening tradeoff between simplicity and coverage (the amount of area a transit route serves).

“Legibility is the thing we talk least about, how easy is it to understand a network,” explained planner and transit guru Christof Spieler last month at the East Lake Brewery, just off Lake Street. “[And legibility] is one area where the Twin Cities isn’t doing very well.”

At a recent reading of his new book, “Trains, Buses, People: An Opinionated Atlas of US Transit,” Spieler presented his good transit tips for how to design effective and efficient transit systems. He brought up legibility as a key site of planning neglect.

During the talk Spieler pointed to the A Line (Snelling/Ford bus rapid transit) as an example of a great, highly legible bus route, even going so far as naming the A Line “probably the best bus route in the US.”

“Where does it go?” Spieler asked. “You can learn everything you need to know by simply looking at the station. It’s got a route map, it’s got a schedule, it tells you everything. It doesn’t take you on any weird branches, but it tells you when the next bus is coming.

That’s awfully high praise from a self-described “opinionated” bus guy, who has visited and studied every one of the 50 largest transit systems in the country.

Yet Spieler did not mince words when it came to other routes in the Twin Cities’ system, which have frequently branching and less “legible” routes like the No. 3, the No. 6, or the No. 64, which he points out has five different branches going all different directions on St. Paul’s East Side. Complex routes like these, he said, “will work for you if you make the same trip every day, but if you’re a newcomer trying to understand the system, or you’re somebody who makes different trips over the course of your week or your month, this makes riding transit a lot harder.”

A simpler future for bus riders?

Key transit routes like the No. 21 might be getting a reboot as Metro Transit’s arterial BRT system begins to roll out in earnest over the next few years. Already, the A Line, which opened in 2016, has become a ridership and cost-saving success — at less than $30 million, the project is a tiny fraction of the cost of the in-progress Southwest Light Rail, but already serves 5,000 daily riders — and the agency is planning to roll out more new BRT lines in the next few years.

The first to come is the C Line down Penn Avenue on the west side of Minneapolis, set to open in June. It’ll be quickly followed by the D Line, serving Chicago and Fremont Avenues; that’ll probably the most important transit project in the city, as the No. 5 route has the highest ridership of any non-rail route in the system.

But then, flying under the radar, are two more key projects — including the B Line, which will provide upgraded BRT service along the route of the No. 21.

“Our BRT is really focused on providing fast and frequent connections, and improving the speed and reliability of the service part of that is legibility of the system,” said Adam Smith, senior planner working on the B Line project.

The question facing Smith and agency planners is whether the new B Line should follow its current complicated route, jogging north over I-94, or whether it should take a simpler and more legible course to downtown St. Paul.

“It may be that some of those branches are no longer necessary based on ridership,” Smith said. “Or maybe a different transit solution is needed in some places. The focus really is on making a convenient, easy-to-use system that provides fast and reliable service to our customers.”

That might mean some changes to the complicated No. 21 route, straightening it out like a paperclip to extend all the way to downtown St. Paul.

Return of the Selby-Lake route?

The No. 21’s Selby-Lake-Marshall-University Avenue route wasn’t always this way. During the dawn of the streetcar era, the Selby-Lake streetcar was one of the key east-west connections linking Minneapolis and St. Paul at the hip. In those days, it was much simpler.

“The University Avenue line opened in 1890; the Como Avenue line was 1898; Selby-Lake was 1906,” explained Aaron Isaacs, who literally wrote the book on Twin Cities streetcar history. Isaacs is helping with a next issue of the Streetcar Museum magazine, which will be devoted to the Selby-Lake line.

When it connected the two cities over the then-15-year-old Lake/Marshall bridge, the key to the streetcar’s success was its straight shot. It skipped downtown Minneapolis altogether and offered a straight east-west shot across the midsections of the two cities. Unlike the other inter-city streetcars, the Selby-Lake line ran through the fast-growing, wealthier southern reaches of the city, and became a key transit connection for thousands of people on both sides of the Mississippi River.  

But a funny thing happened on the way to downtown St. Paul. In 1993, a central bridge on Selby Avenue over Ayd Mill Road was replaced, and the No. 21 was detoured north during the construction to jog up to University Avenue. There it skirted the strip malls and stores on the other side of I-94, ridership spiked with the new detour, and so even after the bridge was replaced, the agency left the odd detour in place.

And yet, the zig-zag routing and multiple branches run counter to some goals of transit planning, which have to weigh legibility and speed against greater coverage. With the new BRT model set to be expanded along the 21 line, the time might have come for the bus planners, almost 30 years later, to put the Selby-Lake line back in its original location.

“That’s one big question,” admitted Adam Smith. “Does it make sense to continue the B Line to downtown St. Paul? And a corollary to the question: Does it make sense to continue the existing alignment that the route 21 takes between Snelling and Lexington, between Snelling and Hamline using University Avenue, and crossing 94 twice? Or does a different route make sense, using Marshall and going down to Selby?

Adding to the ever-shifting dynamics of the transit ridership are some changing developments in the center of St. Paul, including the new Allianz Field soccer stadium, and the new six-story mixed-use developments at Snelling and Selby, right where the new bus might go.

Those will be the key questions that the agency is taking to the community in a series of public meetings along the corridor over the next few months. The first open house is on May 1 at Minneapolis’ South High School, with one the following afternoon at the Merriam Park library on Marshall Avenue. If all goes well, and legislative funding comes through, the new line might be up and running in less than five years. Maybe by then, if the agency can iron out the legibility and ridership priorities, riding the Selby-Lake bus might mean something new to the next generation of Twin Cities transit riders.