We all use journey planners to figure out how to get from one place to another - be it Google maps or sites like gothere.sg. We know that these work on a large corpus of data like the travel times, wait times and also use the arrival times at each stop. And on all this data they apply algorithms to get the shortest path.

How long does it really take to build a journey planner? Can we build a simple journey planner in an evening?

What will we need? - we need the data on the bus routes like origin, destination, frequency etc - we also need the list of stops on the route - We can get this data from various sources - government data,or from data scraping - we need a way to represent the data as a graph - quickly and efficiently - we need a library that lets us search this graph efficiently to find the shortest path