## 3 Selecting and Defining the Scenarios
### Essential Parameters to Define the Scenario  
The selection of scenarios to demonstrate the coexistence of railways and roads is highly complex since it depends upon multiple parameters. If we consider telecommunication infrastructure sharing, radio access network sharing parameters, and elements that are coupled with network topology components that are presented in Table 1, then the following variables are taken into the consideration to define the scenarios:  
* **Telecommunication Network Elements**: To define the railway and road coexistence scenario, telecommunication network parameters such as radio access network (RAN), backhaul, and core are considered as one vital parameter. Railway and road access networks can be shared or dedicated for both domains. Similarly, backhaul and core can be dedicated or shared [7].  
T6 R3C2: different-serving technology is used in the access network, each domain has its own dedicated RAN, and the core network is shared by both domains. T7 R4C1: different-serving technology is used in the access network and the RAN is shared by both domains, but both domains have their own dedicated core network. T8 R4C2: different-serving technology is used in the access network and each domain shares the access network and the core network. (B) **Mobility Parameters:** The speed of the vehicles and the operating region of vehicles are also considered as shaping parameters to define the scenarios, e.g., train versus high-speed train versus urban train versus regional train versus highway versus road [7].  
Nomenclature used to represent the telecommunication infrastructure is given below:  
* M1: mobility of highway and tram;
* M2: mobility of highway and urban train;
* M3: mobility of highway and regional train;
* M4: mobility of highway and high-speed train;
* M5: mobility of road and tram;
* M6: mobility of road and urban train;
* M7: mobility of road and regional train;
* M8: mobility of road and high-speed train.  
(C) **Topological Elements in Civil Engineering Infrastructure:** That deployed railway track components are parallel or perpendicular to roads is also an essential factor to define railway and road coexistence scenarios. This also includes transport infrastructure such as open places versus tunnels versus bridges [7].  
Nomenclature used to represent the telecommunication infrastructure is given below:  
* P1: railway tracks parallel to the road, open-air/bridge, the same plane;
* P2: railway tracks parallel to the road, open-air/bridge, different planes;
* P3: railway tracks parallel to the road, tunnel, same plane;
* P4: railway tracks perpendicular to the road, open-air/bridge, same plane (level crossing);
* P5: railway tracks perpendicular to the road, open-air/bridge, different planes;
* P6: railway tracks perpendicular to the road, tunnel, different planes.  
(D) **Services:** Services and applications defined for railways and roads play an important role in defining the scenario. For instance, speed-limit-monitoring applications, traffic rule violation monitoring applications for vehicles, applications to monitor the railway tracks to locate cracks, etc.