A train journey can involve one or more trains to get you from where you are to where you are going. Often this will be between trains run by the same company (eg from a fast to a stopping Southeastern train at Bromley South) or different lines (eg from District to Central lines at Mile End). You may have to walk down several corridors (eg Bakerloo to Northern lines at Charing Cross) or change between types of train (eg Southeastern and DLR at Woolwich Arsenal). In all the examples so far the changing has been done within one station so it is just a continuation of the same journey with no need to touch out and back in again. But what if it isn’t?
Out of Station Interchanges
At most London terminal stations you have to go through gates between the National Rail platforms and the concourse, while the Underground station is through a further set of gates in its own ticket hall. Sometimes you have to go out onto the street to walk between stations (eg Shadwell, Shepherd’s Bush) and sometimes two nearby stations are deemed close enough to allow interchange between them (eg New Cross and New Cross Gate). In each of these instances the Oyster system allows you to join two journeys together as long as you don’t take too long between touching out at one station and in at the other. This is known as an Out of Station Interchange, or OSI for short. After years of having to make freedom of information requests to get the details, TfL now publish the raw data on their website. However, it is far from user friendly, so we have expanded on the detail and have the complete list here. Note that the page can take a few seconds to load.
The Oyster Control Centre has the ability to set and remove emergency OSIs in real time according to locally made requests. These will typically cater for short term (un)planned station closures and some weekend engineering work. An EOSI will be set at a number of stations and will allow interchange between any of those stations within 30 minutes, including re-entering the same station. These EOSIs are not included in the main list because of their extremely fluid nature.