The company that runs commuter trains in Stockholm, Sweden has employed mathematicians who discovered a reliable algorithm to detect subway delays two hours ahead of time. This algorithm gives 'Stockholmstag' the knowledge they need to inform commuters of the various wait times they may incur because of small subway delays much further down the line.
In the same way that 'NextBus' allows travelers to see the number of minutes the next few buses will arrive at their stop in, this information can improve commuters' planning and travel decisions. However, more than just a GPS system, this process is new in that it is predictive instead of simply descriptive. Therefore, it can help people make more informed decisions on whether they should drive, bike or train to work as well as manage expectations resulting in fewer complaints for the train system.