Hello. Welcome to the Electric Vehicles and Mobility course. In this first video, we will have a look at the interactions between urban forms and mobility. Cities are places of organized central or local powers defined by administrative boundaries. Their urban character is defined by a minimum number of inhabitants. Urban zone definitions are given by national statistical offices and can change from one state to the other. In France, the threshold is set to 2 000 inhabitants gathered together. According to the data collected from the member states by the United Nations, today, over 54% of the world population lives in cities. In addition to these demographic criteria there are morphologic criteria. The urbanized area is defined according to the fact that constructions are uninterrupted. For instance, in France, constructions are considered as uninterrupted if constructions are separated by less than 200 meters. In some cases, the urbanized area can stretch beyond the administrative boundaries of a city. In that case, the relevance of population estimates based on administrative boundaries can be questioned. Cities are characterized by a high land occupation level. Housing units are close to each other, there are high-rise constructions, and the land and the underground are heavily used. Population density, meaning the number of inhabitants per square kilometer, is high or even very high. The average density of Asian city centers is about 40 000 inhabitants per square kilometer. In North America and Europe, densities are lower. Even though the density of European cities, about 10 000 inhabitants per square kilometer, is higher than that of American cities which is somewhere between 2 000 and 5 000 inhabitants per square kilometer. Inner Paris is in-between since the city has over 20 000 inhabitants per square kilometer. The urban growth is characterized by a strong concentration of the population but also by an urban sprawl towards the countryside. Researchers talk about urban sprawl or peri-urbanization. According to the center-periphery model, densities tend to decrease based on the distance from the city center. The so-called compact cities are the opposite of the so-called sprawl cities. The urban structure of metropolises differs according to the population density, according to the more or less high level of job concentration, but also according to the part of the population which still lives in the area mainly reserved for activities. The density and diversity of urban functions influence the organization of daily trips, the distance traveled and energy consumption. At the end of the 1980s, two Australian economists, Peter Newman and Jeffrey Kenworthy, established a connection between urban density and fuel consumption by inhabitants for their daily trips. The two researchers compared 37 metropolises from North America, Australia, Europe and Asia, considering the number of kilometers traveled by car, the average car occupancy rate, an estimation of the energy consumption of the vehicle fleet, as well as the number of passengers for each public transport mode, the average distance traveled using public transport, and an estimation of the energy consumption of the different public transport modes. Three main city groups have emerged on their result curve. North-American and Australian cities are characterized by low urban densities, long distances traveled by car and a high fuel consumption. European cities have average figures. Their population density is in the middle, just like their energy consumption for private transport. Finally, Asian cities are very densely populated. This boosts short-distance travels and the use of public transport. They also have a very low fuel consumption. High urban densities facilitate public transport network viability while they make it more difficult for private transports, which leads to network congestion but also to an increase in accidents and pollution. This Asian city model is under pressure today in a situation where individual motorization is shooting up which leads to an increasing number of cars on the roads. Thanks to the location of people and activities and their relative proximity, it is possible to estimate the accessibility level of the populations to urban functions. In other words, we can measure the mobility potential of individuals in the city. Daily mobility refers to all the travels of a given population in their usual setting. The mobility characteristics of an individual, in other words the number of daily travels, the travel distance, etc., depend on socioeconomic factors such as the level of income, the household size, the presence of children, the socio-professional category. The residential location also plays a major role. It helps explain the motorization rate, the daily travel distance and the use of different transport modes. For illustrative purposes, let us compare the results of three household-travel surveys made in the metropolitan areas of Paris in France, Sao Paulo in Brazil and Mumbai in India. Inhabitants of the Parisian metropolis make more trips and travel more kilometers each day than inhabitants of Sao Paulo or Mumbai, all this with a relatively constant time and money budget. These mobility differences between urban conglomerations can be explained by higher motorization rates and a more intensive use of cars in the Parisian region. These differences can also be seen in the travel mode distribution. Car travels represent a more important part of all the travels in the Parisian region compared to the other urban conglomerations. Notice how important walking is in these three cities. In the great Northern metropolises such as the Parisian region, peri-urbanization and the functional specialization of the locations, alongside the democratization of cars, have contributed to the evolution of urban mobility characteristics. Daily travels have become more and more divided. These evolutions came along with an increase in the travel distances, and an increase in the household motorization and in the use of cars. They had a rather adverse effect on public transports. The issue for public authorities is to coordinate urban development and transport planning. This injunction is all the stronger in a situation where sustainable mobility is promoted and energy consumption, thus the use of private cars, must be controlled. The town planning-transport coordination refers to theoretical models such as transit-oriented development which is very popular in Europe and North America. It aims at increasing density along railroads. In order to implement this coordination, modeling tools are required. They are used to simulate interactions between land use and transports over several decades, just like documents for the planning and contractualization of these politics. To conclude, remember that urban forms determine travel modes just like travel modes determine urban forms. These interactions have economic, societal and political impacts.
