Hello and welcome to this fourth block. In this block, we will talk about the management of urban transportation systems, the challenges these systems face, and all this more or less in the context of efficiency. Now, this block is composed of five different sessions. So in the first session, very briefly, I will introduce you to the main features of the urban transportation-- the building blocks of the urban transportation systems. Then we will talk in the second block about managing these systems. We will hear from an expert on what the challenges are for managing these urban transportation systems, and then we will hear from another expert what the challenges are from an operator's perspective. Finally, I will talk about the broader challenges and the opportunities that arise in the context of the new things that are recently happening, that are recently <i>affecting</i> urban transport. Now, the first block, as I said, is basically about the basic-- the main features of transportation in cities. It is quite simple, but it is, nevertheless, essential to understand these features. I would like to first talk briefly about how transport relates to the structure of the city and then about the physical infrastructure: the transportation modes and the interfaces. Transport is clearly the most structuring infrastructure of a city. Remember when we talked about energy, and electricity in general, we said that this is the lifeblood of the city. But transport is the structure of the city. And it basically has two elements. One is housing. Housing, or the built environment more generally, is closely related to transport. The way the city is structured in terms of housing will determine what kind of transport you can develop. So if you think, for example, of a medieval Italian city, what kind of transport infrastructure possibilities do you actually have there? What kind of mobility possibilities do you have there? Or if you take a big city that has been developed after the second World War, the houses are structured, the way the houses are arranged, structures transport very very differently. but it also works the other way around. So if you have a good transport offer, let's say a very good metro system into suburbia, that will affect the way the housing is being developed, or the industrial and the commercial development that happens. You build shopping malls where the metro stations are. Transport is also a significant driver of urban energy consumption. We have seen in the last section that transport consumes 25% of the energy that goes into a city. And so whatever you do with transport, it affects energy consumption, and it will affect pollution. Now let's quickly go into the basic infrastructures of transport. There are underground transport infrastructures, like metro tracks, like train tracks. Then above the ground-- the majority of the things are above the ground, like surface train tracks or surface metro tracks. But the big chunk of the city is taken away by roads. Yet, on the roads you have several things. You have the tram tracks, you have the light metro tracks, that take off some space from the road. You have dedicated bus lanes on the road. You have sidewalks that are on the road, and then you have, sometimes, dedicated bicycle lanes on the road. So this, together, makes the basic infrastructure of the city. Now, on top of that, you have the main transportation modes that use these infrastructures. So you have public buses, trams and metros that use the road or the underground tracks. You have cycling that uses the sidewalks or the street, because there may be no sidewalks, you have driving cars which basically use up most of the roads, but are recently being pushed back by other transport modes, you have taxis that use the roads and you have pedestrians that use the sidewalks, if they exist, or also the road, in which case this is dangerous. And then you have, of course, the trains and the metros and the trams that use the surface tracks. Now, the third element here are the interfaces. And the interfaces take other space - infrastructure space. You have bus stops. Bus stops use a piece of the road, but we know that actually bus stops often use a piece of the sidewalks or even of the bicycle lanes. We have cycling stands, we have parkings, which use up a lot of space in the city, because actually most of the time the car stands still. It drives into the city in the morning, it drives out in the evening again, and during the rest of the day it occupies space without actually any active productivity of the space. Taxis use taxi stands, pedestrians use sidewalks, and then we have stations above and under the ground. Those are the main interfaces, and all these things together make up for the transportation infrastructure of a city. In this session, we have basically looked at the main features. It is quite trivial. You have the key elements here, but it is essential to understand how things are then managed from there. In the next session, I will talk about the management of these urban transport infrastructure systems. Stay tuned.