Sunday, March 21, 2010

Subway Map III

(Subway Map II is here.)

Subway Map III: Express and Local

Last time I rambled on and on about using symbols for express and local stations. Among comments in the nyc.transit newsgroup was this from Joe Korman:

Way back in the 1970's I was on the TA map committee that designed the original version of the current map. ...

One of the things the committee agreed on was the *express* and *local* designations. We came to an understanding that it needed to be broken into two parts:

The physical attribute of the line (two-three-four tracks) and platforms

The stopping pattern of the trains that use those tracks.

For example, at the time, the *F* was called the 6th Ave Express, but it ran local in Manhattan, express in most of Queens, express daytime between Continental and 179th, and express in Brooklyn in the rush hours.

The result was the the verbose chart that appeared for years afterwards, showing for each marker letter or number, by time of day and by borough, whether it was express or local. I think the chart format was an improvement over the paragraphs of text that had been in use.

The number of cases of trains running express in one section and local in another has greatly increased starting in 1967. It is very difficult to express the routings graphically if we insist on the letter and number markers as the basic units that must be shown.

It's interesting that the committee suggested giving up on showing routings by colored lines, and created a test map with all the lines in red and all stations shown by blobs. That's as simple as you can get. The marker letters and numbers still cluttered the map by being shown next to every station name and also by colored circles next to the red lines at strategic points.

Notice on the proposed red map that the 1967 colors for markers were still in use. The final plan adopted and seen on maps since 1979 was to color-code by main lines, so that for example the 1, 2, and 3 all became red instead of three different colors. The new colors required changing an enormous number of signs throughout the system.

The ten colors are a nice synthesis of the pre-1967 three-color concept and the fairly wild concept (from 1972) of different color shades for all twenty-four markers. Now the colors actually meant something. All the green routes ran on the Lexington Ave Line, for example. But no names were assigned to the colors.

I think they missed an opportunity to simplify by not naming the colors. I think all the diagrams since 1967 have had a problem with level of abstraction, an insistence on including minutiae of train routings that could be left off the system map.

Here's an extreme example of how names could be used on a station entrance sign at street level.  It's extreme because there are only a few stations with services on four main lines. But even here it reduces eight things to four things. In most cases there would be only one or two line names.

Why this is better is that some service changes would not require new signs. For example if the train service to the Nassau St Line changes from M to J, no change is needed on the entrance signs. If there is no longer any service to the Nassau St Line, the sign needs changing, but that's a bigger difference.

As an example: some years back the 2 and 3 swapped terminals in Brooklyn, and all the stations beyond Franklin Ave needed changes to their entrance signs even though the change made no difference to people riding between Brooklyn and most Manhattan points. The stations still had Seventh Ave Line service, and only people riding north of 135th St Manhattan cared about the change.

A really secondary point is that at Borough Hall, the part-time Nassau St Line service does not need to be listed first. That was done solely because letters come before numbers (apparently) and M is the first letter here alphabetically. In my graphic I have put the Lines in what I think is the order of passenger traffic from this point.

Actually what I was going to write about today was the problem of trains that run express in one place and local in another. There weren't many before 1967 but there were some.

The IRT system had the prime example dating back to the opening of the Brooklyn lines beyond Atlantic Avenue in 1920. A couple of track maps I made in 1996 are here and here. First let's see what the problem is.

The local trains on the IRT's two Manhattan main lines ended (and still do) in lower Manhattan: the Lexington Ave Line at City Hall (later Brooklyn Bridge) and the Seventh Ave Line at South Ferry. The express trains continue to Brooklyn by separate routes and come together at Borough Hall. So far so good. But from Borough Hall out the Brooklyn main line to Utica Ave, it's a four-track subway built in the usual manner with express and local stations. The layout of the tunnels routes the Seventh Ave Line to the local tracks. Therefore, from 1920 to the present, Seventh Ave express trains are local trains in Brooklyn.

How do we show express trains running as local trains?

The Interborough Rapid Transit company map took the obvious course. Just use the symbols for express and local stations.

There's a lot of ambiguity here. The two simple circles at Borough Hall raise the most questions: whether some trains skip the station (no) and whether trains coming in via Clark St end there (no). But you know what? People figured it out.

Hagstrom and others followed the same convention. I won't show you. The original Hagstrom in 1936 even copied the idea of showing Borough Hall as two local circles, but changed eventually to two express circles, as part of the new concept of using express circles for all stations where express trains stopped (see Subway Map II for more than you want to know about this).

For the new Transit Authority map in 1958, a new convention was adopted of showing the Brooklyn IRT as two parallel lines. By doing this, the stations could all be shown with the express station symbol, and even more importantly it was finally clear which express trains ran as locals. Here's a 1964 map.

There's one little oddity there. Nevins St and Atlantic Ave are shown with two station symbols, although they are single stations, but at Franklin Ave the two lines combine for one station symbol. The difference is not the physical layout of the stations, since Nevins and Franklin both have two island platforms allowing easy change between trains. I think the main reason was to simplify showing the junction just east of the station. Both express and local trains ran to both the Flatbush and New Lots branches (at various times of day).

(By the way the numbers 4 and 5 near Franklin Ave are not train markers. They indicate the location of two points of interest, the Brooklyn Museum and the Brooklyn Botanic Garden.)

Once the 1967 changes were made, the whole thing looked much simpler! No, I don't mean it. Here's a 1968 map.

It's still clear that the Seventh Ave Line, or, as shown, the 2 and 3, runs as the local service. The name rectangles are a little oddly placed, with the red line for 2 barely touching some of them. They just don't play well with all the diagonal lines in this area of the diagram.

Notice the red names for the stations with both express and local service, so to speak.

(Digression. Notice that DeKalb Ave, where six lettered train routes stop, is not shown with a red name! I mentioned its peculiar nature in Subway Map II: four tracks facing two island platforms (a conventional express and local station) plus two bypass tracks without platforms. All earlier maps I have seen showed it with the symbol for an express station.)

And here's the current generation of subway map. As we saw previously, it uses blobs for express-only stations. That provides a way to make the combined express and local stations stand out, as they should. Using separate colors for the IRT Seventh Ave and Lexington Ave routes pays off here too.

It's a little odd that the double blobs form complete circles on the branch to Flatbush Ave but paired half-circles west of there, but it still seems clear. Nevins St should have the express and local symbol, but the diagram is really cramped for space right there, so maybe we can overlook that anomaly.

The most awkward thing is the extra green line between Atlantic Ave and Franklin Ave. Overnight, the Lexington Ave Line runs local to the Flatbush Ave branch, so there need to be green blobs (half blobs) at the local stations, but doing that obscures the point the Lexington runs express when most people would be riding, and so we need the extra line to show that! But then there's an inconsistency: in the next section from Franklin Ave to Utica Ave, the Lexington runs express during the same hours, but the graphical representation is different. Why? Because it does not run there overnight at all, so no green blobs are needed at the two local stations. It's a little unsatisfying as a graphic.

Did I just say that using red and green "pays off"? Maybe not. If the two IRT main lines were the same color, this would look simpler. (It would also look simpler up in a section up in the Bronx.)

Another way to make the diagram simpler is not to show routings that happen only overnight.

There are other cases, but I will spare you. One is the Queens IND lines ; both the F, which Joe Korman mentioned, and the E have always run as express trains in Queens but local trains in Manhattan. Another is the IRT's "Through Express" trains in the Bronx on the Third Avenue El and the West Farms (2 and 5) line, where some express trains continued to skip stations where other express trains ran as locals. The bottom line is that the concept of trains being express or local never did work.

I might eventually continue this with a discussion of transfer stations, but I want to move on, so I won't do it now.

Next time: Crooked Brook.

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