Something I learned this week about the complexities of managing London’s smart-card ticketing system,
Starting with 700 stations, Oyster does not know the destination when you tap in. So the system has to hold 700 times 700 possible fares.
Then there are alternative routes, where you have to allow for people doing ‘weird and wonderful things’. As a result Oyster allows for up to 32 different routes between any origin-destination pair.
Then there are peak and off-peak fares. Here Oyster has built in ‘stretch’ which could accommodate up to 16 different time bands over the day.
Add in adult, child plus youth, senior, unemployed and other concessionary fares and the total number of combinations in the system comes to 216 million fares. That is, of course, irrelevant to the customer, who knows that, however he or she travels between Zone 1 and Zone 2, the peak fare will be £2.90.
Source: Modern Railways magazine, March 2016, p73