# Interdisciplinary Urban Tunnel Control within Smart Cities
## 4 Discussion  
An urban tunnel is often presented using the word \"Smart\". In most cases, it however focuses on using new technologies, such as automated incident detection [34], emergency management and lighting [35], energy efficiency [36], or, for example, predictive maintenance [37]. Our aim is to move beyond new technology to integrated control strategies. [PERSON] et al. [38] classifies a road tunnel into so-called urban underground infrastructure. They claim (for example, with Shanghai and other world cities) it to be an important part of current and future megacities. The authors confirm our conclusions that proper integration and effective and joint management of various city subsystems is essential. The impact of proper integration on sustainability is further elaborated for example in [39; 40] and on an example of urban utility tunnels also [41]. The importance of implementing the cooperative control strategies is further discussed in [42]. [PERSON] et al. claim that a highway management without proper integration to adjacent urban intersection controllers is not sufficient. They provided a model for the mixed environment and used model predictive control to optimize the traffic control at the intersections, ramp metering and speed harmonization. Our paper clearly focuses on a similar approach, when the adjacent city network influences the parameters of the tunnel control system. As part of our control design, we managed to convert the cooperative tunnel management into a well-known method of harmonizing traffic flow described in [43; 44]. It is therefore possible to use these control results to determine the required key performance indicators (KPIs) of whole district area. The presented results of this paper are in accordance with the ongoing fourth industrial revolution [45], the basic feature of which is the interconnection of sub-subsystems into more complex system. The importance of understanding the distributed nature of the control problem was described in [46]. An example of this trend is also the concept of smart cities and the interconnection of its elements, such as the road urban tunnel. The \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Day of Week**} & \multirow{2}{*}{**Phase**} & **Sum of Flow** & **Total Cost (mio** & **Index: Total Cost** & **Average Speed** \\  & & **(veh/day)** & **CZK)** & **Divided by Sum of Flow** & **(km/h)** \\ \hline Sunday & BEFORE & 3,017,261 & 18.97 & 6.29 & 53.8 \\ Sunday & AFTER & 2,950,674 & 18.35 & 6.22 & 54.9 \\  & Change (\%) & \(-2.21\%\) & \(-3.28\%\) & \(-1.10\%\) & 1.99\% \\ Tuesday & BEFORE & 4,351,693 & 31.50 & 7.24 & 50.5 \\ Monday & AFTER & 4,447,797 & 30.90 & 6.95 & 51.5 \\  & Change (\%) & 2.21\% & \(-1.89\%\) & \(-4.01\%\) & 1.99\% \\ \hline \hline \end{tabular}
\end{table} 
Table 1: BEFORE-AFTER analysis results with respect to changes in the traffic flow (veh), total cost (mio CZK), index and average speed (km/h). subsystems can no longer be controlled by standard methods based on the collection and processing of local data, but it is necessary to use artificial intelligence algorithms that can work with knowledge bases based on ontologies and perform more sophisticated decision-making and management of these complex systems [47]. In order to be able to specify the impact of certain control strategies on the entire city, we have moved beyond the traditional key performance indicators (KPIs) [48]. We offered a solution to measure the environmental and social impact of congestions by its monetary equivalent. This allows the control strategies to take into account integration of various subsystems in a distributed environment. In this paper, we focused on an example of how to approach the management of a road urban tunnel with knowledge of the traffic situation in its neighborhood. The above results show that even if the tunnel is controlled so that the passage of vehicles is minimal, it is far better than if it was closed, as is the case today.