## 3 Results and Discussion
### Cocitation Analysis: Influential Journals, References and Authors
\begin{table}
\begin{tabular}{c c} \hline
5 & [PERSON], _Planning Algorithms_, Cambridge University Press, 2006 [62]. \\ \hline
6 & [PERSON], [PERSON] and [PERSON], “Approximate dynamic programming methods applied to far trajectory planning in optimal control”, 2014 IEEE Intelligent Vehicles Symposium Proceedings, Dearborn, MI, 2014, pp. 1085–1090 [63]. \\ \hline
7 & [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON], “Field operational testing of ECO-approach technology at a fixed-time signalized intersection”, 2012 15 th International IEEE Conference on Intelligent Transportation Systems, Anchorage, AK, 2012, pp. 188–193 [64]. \\ \hline
8 & [PERSON], [PERSON], [PERSON] and [PERSON], “A real-time adaptive signal control in a connected vehicle environment”, _Transportation Research Part C: Emerging Technologies_, Volume 55, June 2015, pp. 460–473 [65]. \\ \hline
9 & [PERSON], Traffic guidance system, Mitsubishi International GmbH, US Patent No. US006418371B1; July 2002 [66]. \\ \hline
10 & [PERSON], Method for controlling traffic, USA, Intel corporation, 2002 [67]. \\ \hline
11 & [PERSON], [PERSON] and [PERSON], “Reinforcement learning for true adaptive traffic signal control”, _Journal of Transportation Engineering_, 129 (3), 2003, pp. 278–285 [57]. \\ \hline
12 & [PERSON] and [PERSON], “Development and Evaluation of a Cooperative Vehicle Intersection Control Algorithm Under the Connected Vehicles Environment”, in _IEEE Transactions on Intelligent Transportation Systems_, vol. 13, no. 1, March 2012, pp. 81–90 [68]. \\ \hline
13 & [PERSON], [PERSON], [PERSON] and [PERSON], “Dynamic Traffic Signal Timing Optimization Strategy Incorporating Various Vehicle Fuel Consumption Characteristics”, in _IEEE Transactions on Vehicular Technology_, vol. 65, no. 6, June 2016, pp. 3874–3887 [69]. \\ \hline
14 & [PERSON], [PERSON] and [PERSON], “A multivariable regulator approach to traffic-responsive network-wide signal control”, _Control Engineering Practice_, Volume 10, Issue 2, February 2002, pp. 183–195 [70]. \\ \hline
15 & [PERSON] and [PERSON], “A real-time traffic signal control system: architecture, algorithms, and analysis”, _Transportation Research Part C: Emerging Technologies_, Volume 9, Issue 6, December 2001, pp. 415–432 [71]. \\ \hline \end{tabular}
\end{table} 
Table 2: Cont. Figure 6: Source visualization of database list “A” obtained by analyzing cocitations. The cocitation analysis of authors was carried out by establishing a minimum threshold of 20 citations for an author; in this way, 195 authors were selected. The resulting network is visualized in Figure 7, where the dimension of a node shows the total link strength of that node as an index of relevance in the network and the vicinity of two nodes shows the connection in terms of cocitations. It must be noted that the cocitation analysis visualization of Figure 7 shows a well-connected network, while the reference analysis reported in Figures 4 and 5 shows a poorly connected network; this means that the main authors in the field are connected in terms of citations among each other, while the specific research papers with high relevance are not connected. This incongruence shows that the more important works have been published without cross-referencing, and this is possibly an indication of a new field of research that might be in an embryonic state. \begin{table}
\begin{tabular}{c c} \hline \hline
**Source** & **Total Link Strength** \\ \hline _Transportation Research Part C_ & 4290 \\ _Transportation Research Record_ & 3678 \\ _IEEE Trans. Intell. Transport. Syst._ & 2962 \\ _Transportation Research Part B_ & 2151 \\ _IEEE Transactions on Vehicular Technology_ & 1294 \\ _IEEE Transactions on Intelligent Transportation Systems_ & 947 \\ _Journal of Transportation Engineering_ & 750 \\ _IET Intelligent Transport Systems_ & 685 \\ _Org. Lett._ & 644 \\ _Intelligent Transportation Systems (itsc)_ & 618 \\ _J. Am. Chem. Soc._ & 579 \\ _Chem. Commun._ & 530 \\ _Physica A_ & 460 \\ _Sensors_ & 408 \\ \hline \hline \end{tabular}
\end{table}