A while ago, we spotted an anomaly on the tube map and Oyster network: if you travel by London Overground from Clapham to Highbury and Islington via Willesden (clockwise) you stay in Zone 2; but if you head anticlockwise, you pass through Zone 1 at Shoreditch High Street.
This got us thinking as to where the actual Oyster-Zone boundaries physically lie (as opposed to the schematic version shown on the tube map). So here it is, a map of London with the Oyster boundaries laid over on top.
For comparison, we've also added in the actual outer border of the London Boroughs (orange line), as well at the congestion charge (red) and Cycle Hire area (blue, including the recent expansion into Fulham & Hammersmith).
How we made it
To make it, we looked at the Oyster Rail Service map, which schematically shows tube and national rail stations and where they fall within the Oyster system. We then 'joined the dots' with the neatest curved lines possible between the stations. From this more geographical representation, it became apparent where the anomalies were. In large areas where there are no stations to define the zone (e.g. in the south-east of London where there's nothing between the Tramlink and National Rail services), it is very much a 'best guess', but we think it's quite a good one!
What it shows
You can see that the Cycle Hire scheme almost completely covers Zone 1. If the western extension to the congestion charge still existed, that would have broadly covered the Oyster Zone 1 area, too.
It also perhaps goes someway to answering the question "Do I live in London or not?". For some people, 'living in London' equates to the official definition of living in a London Borough. Others might call themselves Londoners so long as they're on the tube map — 'Zone 6 inwards' equals London. The map above helps to visualise which areas fall within Transport for London's zone boundaries.
But look closely, and you will see some strange anomalies, which we'll highlight here for you.
1. Hoxton should be in Zone 2, and only Zone 2. As it stands, it is a Zone 2 AND Zone 1 'border' station, but you can clearly see the Zone 1 area bumps up like an enormous spot, to suck Hoxton into Zone 1. Naughty TfL have promoted it to the inner-most zone in order to justify higher fares for people travelling here. By the same token, Shoreditch High Street should also geographically fit into Zone 2, rather than Zone 1.
2. Where the DLR snakes south to Lewisham, the border between Zone 2 and Zone 3 bends with it to ensure that all the DLR stations south of the river here are 'border' stations between the two zones.
3. Epping should not be in Zone 6. This is another Hoxton-like 'bump', but this time it works in the passengers favour. You could argue that Epping should really be a Zone 7, or possibly even a Zone 8 station.
4. The commuters of Northwood and Moor Park get a good deal, too, with a bump that pulls their stations into Zone 6, and not 7. We think Moor Park used to be Zone 7, and was moved into Zone 6 recently.
Let us know in the comments if you spot any other anomalies.