In this recipe, we will create a routing network from scratch using the QGIS editing tools. Even though more and more open network data is available, there will still be numerous use cases where necessary network data does not exist or is not available for use. Therefore, it is good to know how to create a network and what to pay attention to in order to avoid common pitfalls.
For the task of network creation, the main difference between the Road graph plugin and pgRouting is that pgRouting needs a network node (that is, link start or end node) at each intersection while the Road graph plugin will also use intermediate link geometry nodes to infer intersections if two links share a node. In this recipe, we will create a network, which can be used in both tools.