Continuing the recent series on frequent network maps, today's post is by Aaron Priven, who actually managed the redesign of a network map. I don't agree with everything he says, but the resulting map (current version here in PDF, here in a version that you can pan and zoom online) certainly shows a lot of thought, and it's interesting to see the thought process explained. I'll share my own responses to this map in a near-future post.
Jarrett’s post on frequency mapping, and a number of the comments there, referred to the AC Transit system maps. (AC Transit is the bus system for a large portion of the eastern shore of San Francisco Bay, including cities such as Oakland, Berkeley, Richmond, and Fremont.)
I was the project manager for the redesign of the AC Transit system map back in 2002-2003. As such I am primarily responsible for its design, although most of the specifics were worked out by our cartographer, Kristin Bergstrom, who had previously designed the San Francisco Muni map.
One basic principle we wanted to follow was that there should be a one-to-one correspondence between the ink lines and the bus lines. Many American maps are like the Seattle map, pictured here, where no matter how many bus lines are on a street, they are shown by a single ink line. Trying to understand where a single line goes is very difficult on these maps. One has to hunt around for the bubbles to figure out where the route is going, and sometimes this can be very obscure. For example, on the Seattle map shown in Jarrett’s post, pictured here, there is a Line 30 bubble on Dexter Ave N., and another one further west, on an unlabeled street near Queen Anne Ave. N. How does Line 30 get between the two places? Does it dip downtown and come back in a U, or does it travel on one of the two sets of east-west streets shown? Or does it do something else entirely?
We wanted to make it easy to figure out how to follow where a bus line goes, which we thought was a basic goal of any bus map.
We followed the lead of the Paris and New York maps in using colors designed to be as distinct as possible from neighboring routes, so it would be easy to follow the red, blue, or green line from place to place.
At that time, we were introducing new LED headsign, which were capable of showing several different colors. One compromise we made was that we limited ourselves to the colors available on these headsigns (or as close as we could get in print).
The advantage of using colored headsigns is that it becomes clearer much further away that the headsign is blue than what the route number is. If you’re two blocks away and you want to know whether that bus in the distance is the 11 bus you need, or the 62 bus you don’t, it’s very nice to be able to see the purple light and know that you have time to go get a coffee, because the 11 will be blue-green.
Unfortunately, the color gamut of the headsigns is limited. On the 2001 Paris map, they used a range of different colors – red, maroon, blue, purple, yellow, brown, chartreuse… We did not have those choices. Our choices were restrained even further a few years later when the California Highway Patrol decided the red headsigns looked too much like red reverse lights and started giving tickets to buses showing red! We had to reassign the colors to avoid using red, reducing our palette even further. (We tried to get legislation passed to change this, but while we successfully got legislation to allow us to use most colors, we were still not allowed red.)
For line and bubble symbology, we considered a number of different aspects of each line. We did consider frequency, but we ultimately decided that the most important aspects were variance, span of service, and express running.
Variance: Even more than now, we had a lot of bus lines that had several different variants – different weekday and weekend routes, routes shortened off-peak, two branches serving different areas, and so forth. Many of these did not have distinct route numbers, even using suffixes. We used different dash patterns to show different variants, and keyed the dash patterns to the frequency guide on the back of the map (which had a from-x to-y listing, inspired by Chicago).
Span of service: AC Transit had no regularity when it came to span of service , with different lines operating radically different spans, and while usually frequent service had a longer span, there were many exceptions. There was no standard span for “all day” service. We felt that the most urgent question someone could ask was “can I get home on this line?” For that we decided to base bubble symbols on hours of operation. Originally we had bubble shapes for peak service, 24-hour service, several kinds of all-day service depending on what time the last bus left the origin of the line (after 6 p.m., after 7 p.m., after 8 p.m., after 10 p.m., and after midnight), and a catchall “weird” category for weekend-only service, midday-only service, or other strange hours. If there was any service on the line on weekends, the bubble was solid; otherwise, it was hollow. (I’m not sure where the idea came from that we distinguished Saturday from Sunday service – in fact for years all of our Saturday and Sunday schedules have been identical, except for later service on two All Nighter routes because BART starts later on Sunday.)
As time went on we made some changes, most importantly reducing the number of “all day” bubbles to two, and accommodating the change from 24-hour service on some lines to having parallel 800-series All Nighter lines.
Express running: Clearly if a bus is running on a street but doesn’t stop, that’s an important distinction. Much of our express running is on freeways, but not all, and we have a number of limited stop services. I liked the way this was shown on the Muni map, with thin lines with round stops where the limited stops were, and we copied that, more or less, for our map.
The other important feature we wanted to have was a complete street map along with the transit map, so that people wouldn’t need to consult two different maps. We had a complete street index and intended at some point to add block numbers whenever possible, although the block numbers never quite happened. (The current map does not have all this detail, mainly because of printing costs.)
So that’s what we were thinking back in 2003. I’m not sure we were very successful, and I think much of it needs rethinking. I thought at the time that people who didn’t understand the differences between dash patterns or bubble types would just ignore those differences, rather than be frustrated and confused by their lack of understanding. We didn’t (and don’t) have the money to do user tests of any of this, and I think that’s something we could have found out.
Nonetheless, I think a lot of the principles we adopted are still worth thinking about.
It’s clear from Jarrett’s August 7 post that he uses “The Frequent Network” as a name for service that is both frequent and has a long span of service, but at least at AC Transit the two don’t always go together. Which is a “major route,” a 15-minute service that runs from 6 to 7, or a 30-minute service that runs from 6 to midnight? We’ve had both of those in the past. Maybe this is a detail, and it doesn’t matter as long as “major” is defined in some consistent way, but frequency is just one aspect of a bus route. I, at least, would rather wait 30 minutes for an infrequent bus than wait two hours before finding out that this bus line has no more buses scheduled for the day, or doesn’t run at all today.
We have all kinds of routes, and not all of them fall in the simple categories of “Frequent Network,” “Infrequent All-day services” and “Peak-only service.”
I am still very concerned that on most bus maps it’s too hard to figure out where some lines go. Our service has so many different lines along certain streets (Broadway, MacArthur, Shattuck, the loop around Hayward BART) that on our map individual lines get lost in the elongated pastel rainbow, especially when we’re limited to colors that are so non-distinct. (What do you mean you can’t tell the difference between the three shades of teal??) But I’m not convinced it’s any better to basically combine them all and hope people can search out the bubbles, especially when in the real world that kind of map is easy to make errors in creating. (It’s not at all obvious which bus line a particular ink line refers to, especially if the bus line it originally referred to was rerouted or eliminated some time ago but this ink line was neglected. Little short stretches of ink line, one or two blocks long, end up staying on the map years after the bus line is gone.)
The highway map analogy, with different types of ink lines for different levels of service, would lead to a better conclusion than a flat all-the-same map like Seattle’s. Better a few types of line than just one. But transit is inherently more complex than the street network in that multiple lines can and often do go along the same street for long stretches, and it is important to know which. If you are planning a trip across town, you need to know precisely where your transfer point is, and where particular bus lines go. It needs to be as easy as possible to figure that out.
Ultimately, the question behind all of this is how to show the complexity of our system. In an ideal world we might simplify the system itself, but this wasn't a choice open to us in the map project. We chose to try to capture the complexity of the system in the map rather than hide it away by creating something simpler, since we felt this would mislead potential riders. It is a disservice to passengers to portray the system as other than it is.