Here’s a great late-1970s diagram that I haven’t seen before of Philadelphia’s subway-surface trolley lines. From the looks of things, this might well have been a strip map within the trolley cars themselves.

The subway-surface lines are given full prominence here, with the rest of Philly’s rapid transit rail system represented by very thin route lines mainly confined to the right third of the map. The five trolley routes are treated very diagrammatically, each following a straight path across the length of the sheet. Cleverly, little breaks in each line indicate where the trolley runs along different streets towards its final destination. The 10 runs on 36th, Lancaster, Lansdowne and 63rd on its way out to Overbrook, for example. Angled lines indicate cross streets and the numbers/letters of connecting services, though I think that the type here is a little to small to be read easily – something that can be said for much of the diagram. I wouldn’t fancy trying to read those tiny numbers on a crowded trolley, that’s for sure!

Interestingly, the lines are shown as purple, rather than the familiar green of modern SEPTA maps. Here, green is used to show main line passenger and commuter rail services out of 30th Street, Penn Center and the Reading Terminal. Note that commuter rail services were still under ConRail at the time.

Our rating: A great example of late-1970s minimalist transit diagram design, though readability is a concern due to the small labels on the map. Three stars.

Source: Free Library of Philadelphia