The AequilibraE project is one of the newest portions of the aequilibrae API, and therefore not very mature.
For a better over.overview of the AequilibraE project, please check the documentation listed above, as this page is dedicated to a practical implementation
Create project from OSM¶
However, its first feature is the capability of importing networks directly from Open Street Maps into AequilibraE’s efficient TranspoNet format. This is also time to give a HUGE shout out to Geoff Boeing, creator of the widely used Python package OSMNx . For several weeks I worked with Geoff in refactoring the entire OSMNx code base so I could include it as a submodule or dependency for AequilibraE, but its deep integration with GeoPandas and all the packages it depends on (Pandas, Shapely, Fiona, RTree, etc.), means that we would have to rebuild OSMNx from the ground up in order to use it with AequilibraE within QGIS, since its Windows distribution does not include all those dependencies.
For this reason, I have ported some of Geoff’s code into AequilibraE (modifications were quite heavy, however), and was ultimately able to bring this feature to life.
Importing networks from OSM is a rather slow process, so we recommend that you carefully choose the area you are downloading it for. We have also inserted small pauses between successive downloads as to not put too much pressure on the OSM servers. So be patient!!
Importing networks from OSM can be done by choosing an area for download, defined as the current map canvas on QGIS…
… or for a named place.
Project from layers¶
The AequilibraE project can also be bootstrapped from existing line and node layers obtained from any other source, as long as they contain the following required field for the conversion:
These requirements often create quite a bit of manual work, as most networks available do not have complete (or reliable) information. Manually editing the networks might be necessary, which is common practice in transport modelling .
Before creating a project from the layer, you can understand how to prepare the layers for this task in the documentation page for Preparing a network.
After all field preparation is done, one can import those layers into an AequilibraE project using a dedicated tool in the Project menu in AequilibraE.
Accessing AequilibraE > Project > Create Project from Layers, the user is presented with the following screen.
After running this tool a sqlite file (spatialite enabled) will be created and you can edit the network (create, move or delete links and nodes) and both layers (including node ID and A_Node/B_Node fields) will remain consistent with each other.
If you want a summary of everything that was presented in this page, you can head over to YouTube to see a demonstration of how to download these projects.
Starting in version 0.6 of AequilibraE, centroid connectors can now only be added to AequilibraE projects , and no longer generates new layers during the process.
Before we describe what this tool can do for you, however, let’s just remember that there is a virtually unlimited number of things that can go awfully wrong when we edit networks with automated procedures, and we highly recommend that you BACKUP YOUR DATA prior to running this procedure and that you inspect the results of this tool CAREFULLY.
The GUI for this procedure is fairly straightforward, as shown below.
One would notice that nowhere in the GUI one can indicate which modes they want to see the network connected for or how to control how many connectors per mode will be created. Although it could be implemented, such a solution would be convoluted and there is probably no good reason to do so.
Instead, we have chosen to develop the procedure with the following criteria:
All modes will be connected to links where those modes are allowed.
When considering number of connectors per centroid, there is no guarantee that each and every mode will have that number of connectors. If a particular mode only available rather far from the centroid, it is likely that a single connector to that mode will be created for that centroid
When considering the maximum length of connectors, the GUI returns to the user the list of centroids/modes that could not be connected.
Notice that in order to add centroids and their connectors to the network, we need to create the set of centroids we want to add to the network in a separate layer and to have a field that contains unique centroid IDs. These IDs also cannot exist in the set of node IDs that are already part of the map.