## 5 Example Application to Rome Ciampino Airport  
The airport information needed to support the development of the route planner can be summarized in the below reported list:* Runway(s) in use for arrivals and departures;
* Length, maximum allowed wingspan, maximum allowed aircraft gross weight for each taxiway;
* Location of crossroads between two taxiways;
* Holding points on taxiways;
* Special rules for taxiway use in particular conditions, such as wet ground, poor visibility and daytime restrictions.  
This information is available via the Air National Service Provider in charge of the airport ATCo, e.g., Ente Nazionale Assistenza al Volo (ENAV) S.p.a. for Italian airports, which is thus responsible for maintaining the Integrated Aeronautical Information Package document conforming to applicable international standards [13]. Figure 6 shows the aerodrome chart of the Rome Ciampino airport (International Civil Aviation Organization (ICAO) code LIRA), publicly made available by ENAV in the Italian Aeronautical Information Publication [14]. LIRA airport is selected in this paper only for validation and illustrative purposes, the target airports for the deployment of advanced airport operation concepts being substantially bigger and more complex. Nonetheless, LIRA is a good compromise for initial testing of the algorithm, as well as for understanding the issues in modeling an airport for XRP.  
Figure 6: LIRA aerodrome chart (taken from [14]).  
As reported in the first section of this report, a graph structure shall represent the graph to solve the shortest path problem. The type of graph shall be non-unidirectional, since some taxiways can be travelled in both ways, and weighted, since a distance is defined for each edge. Two separate graphs are built for computing the standalone shortest path solution, that is, one encoding the available paths for the aircraft at arrival and one for the aircraft at departure. The procedure that allows for building the two graphs consists of the following steps:  
1. Identify all crossroads between at least two taxiways on the map. They will be the internal vertices of the graph;
2. Retrieve the distances between each pair of contiguous crossroads. Two crossroads are contiguous if they are on the same taxiway and there is no other crossroad between them;
3. Set a starting vertex on each runway/apron for arriving/departing aircraft;
4. Set an ending vertex on each apron/runway for arriving/departing aircraft;
5. Add an edge for each (portion of) taxiway that connects two vertices. The right way to travel the taxiway at departure/arrival shall be taken into account. Two edges shall be added if both ways are available;
6. Distances obtained at point 2 shall be associated with each edge introduced at point 5;
7. The maximum aircraft wingspan allowed for each taxiway shall be associated with the relevant edges;
8. The maximum aircraft reference mass allowed for each taxiway shall be associated with the relevant edges;
9. Taxiways that cannot be travelled in special weather, visibility and daytime conditions must be noted to insert the proper graph forbidden states in the tool.  
Following this procedure, arrival and departure graphs can be easily built for Rome Ciampino airport and are shown in Figure 7. Source vertices are colored in orange, taxiways crossroads and holding positions are drawn in blue and the end vertices are in red and green. The vertices are labeled using the same nomenclature used in [14], making the resulting graph easily understandable by comparing Figure 7 with LIRA data.  
Figure 7: LIRA airport coding onto arrival (**top**) and departure (**bottom**) graphs for XRP.