You have to remember that the El in the city centre is placed above the street-grid and the stations are close together, similar to the Paris metro. That is one of the reasons for the very tight curves through there. The woodwork you can see is for walking and as a roof; the actual track, as shown, is on steel supports. Interesting that, apart from junctions, there do not seem to be any visual signals, even though the train does stop a couple of times.
It is interesting to use Google Maps and Streetview in the centre to see the effect that it has on the road system. Not all the system is elevated, as some of the modern lines are beneath street level, and I suspect deep enough not to need to follow the street grid. That is different to the system in the NYC metro in Manhattan which replaced an elevated system, though there are still some of those in Brooklyn and away from the city centre. Again, the early London tubes (District and Circle) and the Paris metro lines were built below street lines.