Here’s a fantastic photo showing three versions of the map for the Stockholms tunnelbana, probably taken at the Stockholm Transit Museum. By comparing the three maps and the looking at the stations shown on each of them, I’ve roughly dated each as follows.

The top map is from between November 19, 1958 (when the Farsta station opened), and November 14, 1959, when Rågsved station (shown on the middle map, but not on the top one) opened.

The middle map is from around late 1964/early 1965, as it shows Fruangen and Ornsberg stations (1964), but only shows Ostermalmstorg (1965) as being under construction.

The final map is from between 1967 and 1971, as it’s after Ropsten and Vårberg have opened, but before the extension to Farsta Strand has been built. Interestingly, this extension is shown as being “under construction” on the middle map, but makes no appearance at all on the final map.

What’s truly fascinating about this trio of maps is the rapid transition from geographical map, through a more stylised map (note that it retains some semblance of a coastline where the tracks cross water), to a severe rectilinear diagram in just 13 years or so. Each map is also quite beautiful in their own way.

Route numbers on the second and third maps allow service patterns and short run lines to be shown very effectively. I think the treatment on the final map is one of the best I have ever seen: it’s clear to see exactly which stations Line 13 runs between, for example.

Compare to the current Stockholm transit map (Nov. 2011, 3.5 stars)

Source: frettir/Flickr – I recommend clicking through to the largest image to view the maps in detail