Mobility Revolution

1. Introduction

When addressing the issue of mobility in cities, it is vital to gain a firm understanding of current conditions to inform the development of technology, infrastructure, or public policy solutions. Modern cities have thrived because of mobility innovations; we would all still be commuting on foot or riding horses if it weren’t for the railway and the car (Wegener 2013). While these mobility modes have improved quality of life and access to resources both within and outside of cities, they have also allowed people, retail outlets, and service providers to spread across great distances.

2. Mobility revolutions

Before we explore new mobility solutions, it is important to have an overview of the history of urban mobility. For thousands of years, transportation was largely limited to human, animal, or wind power. This changed dramatically in the late 19th century, when industrialization attracted millions of rural people and immigrants to urban areas, and triggered a period of extreme urbanization. The city of Boston, Massachusetts, for example, more than doubled its population between 1880 and 1920 (Global Boston n.d.). To accommodate this unprecedented urban growth, cities turned to the emerging technology of that time.

2.1 The first mobility revolution

In the 19th century, steam-powered, horse-drawn, and cable-hauled trams had been deployed in cities in a limited way, but the electric-powered tram was the first urban mobility technology that proved to be rapidly scalable. In 1880, the first electric tramway was built by Fyodor Pirotsky, a Russian inventor. In 1881, a commercial electric tramline opened in Germany (Train History n.d.). Soon, electric trams and subways were operational in cities across Europe and the U.S., providing highly efficient mobility to expanding cities. In New York City, elevated electric trains were quickly deployed in the 1880s and soon covered much of Manhattan and Brooklyn. Cities expanded in linear directions along these mass transit routes, while largely maintaining the high-density neighborhood patterns found in older sections of the city.

2.2 The second mobility revolution

Although automobiles had existed since the 1880s, they were mostly expensive luxuries for the affluent. This changed in 1908, when Ford introduced the Model T. This mass-produced car proved to be reliable, easily maintained, and relatively low cost. After the end of World War I in 1918, the national expansion of roadways and affordable cars for the middle class led to a tremendous growth in automobile ownership. The number of registered drivers almost tripled to 23 million during the 1920s (U.S. History n.d.). By the 1950s, electric trams were largely replaced by gasoline-powered mobility modes, enabling the low-density, auto-centric expansion of the suburbs. Urban streets became pathways for automobiles, rather than places of human interaction.

2.3 The third mobility revolution

We are now entering a new mobility era in which three innovations may converge: autonomous, shared-use, and ultra-light electric-drive vehicles. Autonomous vehicles offer the possibility of dramatic improvements in safety, more efficient flow of traffic, and greater access to mobility services (Lang et al. 2017). Shared-use systems can eliminate the need for parking in central cities and provide people with door-to-door mobility, without the need to own a personal automobile. Ultra-light electric-drive vehicles — with less need for the heavy protection required for human-controlled automobiles — can respond to the fact that most trips in a city are by one person travelling a short distance, at a relatively slow speed. This combination will, over time, enable space now used by automobiles to be reclaimed for human activity and more productive functions. If these technologies are properly deployed, and if zoning is modernized, this new era will enable higher density development without the usual traffic and parking problems, helping to address shortages in housing availability and improving urban vibrancy. Lanes devoted to mobility can be reduced, thereby expanding space for cafés, greenery, and other high-value uses. Many crosswalks and traffic signals can be eliminated, creating shared space for pedestrians, cyclists, and a wide range of autonomous mobility modes.

3. Current mobility modes

The use of mobility modes varies greatly from city to city. In Los Angeles, California, the majority of people travel exclusively by car. In New York, most people walk or take the subway. In Melbourne, Australia, many people take the tram to work. In Amsterdam, Netherlands, a significant portion of urban travel occurs by bicycle. In Johannesburg, South Africa, many people use minibus taxis to commute. Although individual preferences vary, some mobility modes are preferable to others because of the external impacts on public health, the environment, and congestion in the network. For example, replacing car trips with cycling benefits the individual travelers by reducing their risk of cardiovascular disease, cancer, and all-cause mortality (Doorley, Pakrashi, and Ghosh 2015). At the same time, the displacement of car trips benefits society because of the reduction of greenhouse gas emissions and pollutants.

3.1 The challenges of current mobility modes

This section dissects the challenges that come with different mobility modes and patterns in modern cities, as well as solutions that are currently being implemented.

3.2 Current mobility solutions

For many decades, transportation engineering was singularly focused on increasing the car-carrying capacity of urban and regional networks, by building new roads or adding lanes to match increased demand. This addressed the problem in the short term, but cities found that additional capacity was quickly matched by additional use. Typically, congestion returned to previous levels within about five years of major improvements, but with much higher numbers of cars using the route, as suburbs expanded and commuting distances increased (Duranton and Turner 2011). This phenomenon is now considered a fundamental law of road congestion. However, new mobility options are emerging that may alter the auto-centric urban development typical of cities around the world. Many of these solutions are based on sharing, rather than private ownership.

4. Understanding mobility patterns with data

4.1 Dimensions of mobility behavior

Many forms of data can be used to help us understand mobility patterns through analysis or building of statistical models. Transportation data sources have traditionally been analyzed at a systemic level, and most cities still use this approach. Cities are divided into zones and transportation behavior is analyzed at an aggregate level using the traditional four-stage model of generation, distribution, mode choice, and traffic assignment (Ortúzar and Willumsen 2011). This is known as the aggregate approach.

4.2 Data analysis and model development

In many areas of urban science, we use models to better understand complex systems or predict how they may respond to changing conditions or interventions. These models are simplified mathematical representations of real phenomena and, in order to be useful, their behavior should closely approximate the behavior of the real system. In Unit 3 of this module, you will learn about agent-based modeling (ABM) and how this can be used to understand, visualize, and predict urban mobility behavior. In ABM, simulated agents have to make decisions, such as which activities to participate in, where to pursue those activities, and how to move between them. Often, agents will have different characteristics or profiles that will influence the choices they make. If no suitable data are available, these decision-making processes may be codified subjectively by a modeler with substantive knowledge. However, if data are available, the agents’ profiles and behaviors should be calibrated using it in order to ensure they are realistic.

  • Alternative specific variables such as the travel time and cost for each mode
  • The actual choice made by the traveler, for example, driving

5. Conclusion

In these notes, we discussed current mobility patterns around the world and some recent attempts to solve them. Although there have been many technological and service-model innovations in recent years, it remains to be seen whether these will positively impact cities in the long term. In order to ensure that innovations lead to sustainable improvements, they must be coupled with an understanding of human behavior in relation to mobility choices. Such an understanding helps us to design appropriate interventions and to predict how people’s behavior will change with the introduction of a new mobility system. In Unit 2 of this module, we will discuss ongoing work in developing next-generation solutions to urban mobility, such as lightweight autonomous vehicles and new kinds of mass transit.

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