Transportation Engineering: Urban Transportation

Urbanization: A dominant contemporary process with a growing share of the global population living in cities.
Transition: It's the process of shifting from a rural to a more urban society.
Statistical Reflection: Urbanization reflects an increasing proportion of the population living in settlements defined as urban, primarily through net rural to urban migration.

Natural Increase:
- More births than deaths in urban areas.
- Directly related to fertility rate and quality of healthcare systems (lower mortality rates, particularly for infants).
Rural to Urban Migration:
- A strong factor of urbanization, especially in the developing world.
- Migration accounts for 40-60% of urban growth.
International Migration:
- Growth in international migration is an important factor in the urbanization of major gateway cities.
- Examples: Los Angeles, Miami, New York, London, and Paris.

Urban Form:
- The spatial imprint of an urban transport system and adjacent physical infrastructures.
- Confers a level of spatial arrangement to cities.
Urban (Spatial) Structure:
- The set of relationships arising out of the urban form and its underlying interactions of people, freight, and information.
- Evaluates the extent to which specific urban structures can be achieved with specific transport systems.

Elements of the urban transport system (modes, infrastructures, and users) have a spatial imprint that shapes the urban form.
Each city has different socioeconomic and geographical characteristics, so the spatial imprint of transportation varies accordingly.
North American cities: Urban form shaped by the automobile.
Cities in other parts of the world: different modal preferences and infrastructure developments lead to different urban forms.
Urban transport system: Represented by its spatial interactions, as each city has its own circulation pattern of passengers and freight.

The urban spatial structure can be categorized by its level of centralization and clustering:

Centralization:
- The setting of activities in relation to the whole urban area.
Clustering:
- The setting of activities in relation to a specific part of the urban area.

Nodes:
- Reflected in the centrality of urban activities.
- Related to the spatial accumulation of economic activities or accessibility to the transport system.
Linkages:
- Infrastructures supporting flows from, to, and between nodes.
- The lowest level of linkages includes streets, which are the defining elements of the urban spatial structure.

Pedestrian Areas:
- Amount of space devoted to walking.
Roads and Parking Areas:
- Amount of space devoted to road transportation (moving or parked).
- In a motorized city, approximately 30% of the surface is devoted to roads, and another 20% is required for off-street parking.
Cycling Areas:
- In a disorganized form, cycling shares access to pedestrian and road space.
- Attempts to create spaces specifically for bicycles in urban areas, with reserved lanes and parking facilities.
Transit Systems:
- Many transit systems (buses, tramways) share road space with automobiles, often impairing their respective efficiency.
Transport Terminals:
- Amount of space devoted to terminal facilities such as ports, airports, transit stations, railyards, and distribution centers.

Collective Transportation (Public Transit):
- Purpose: To provide publicly accessible mobility over specific parts of a city.
Individual Transportation:
- Includes any mode where mobility is the outcome of a personal choice.
- Examples: automobile, walking, cycling, and motorcycle.
Freight Transportation:
- Cities are dominant centers of production and consumption.
- Urban activities are accompanied by large movements of freight.

The Walking-Horsecar Era (1800-1890):
- Even during the industrial revolution, the dominant means of getting around was on foot.
The Electric Streetcar or Transit Era (1890 - 1920s):
- The invention of the electric traction motor created a revolution in urban travel.
The Automobile Era (1930 onward):
- Automobiles were introduced in European and North American cities in the 1890s, but initially, only the wealthy could afford them.

Type I - Completely Motorized Network:
- Represents an automobile-dependent city with limited centrality and dispersed activities.
Type II - Weak Center:
- Represents the spatial structure of many American cities where many activities are in the periphery.
Type III - Strong Center:
- Represents high-density urban centers with well-developed public transit systems, particularly in Europe and Asia.
Type IV - Traffic Limitation:
- Represents urban areas that have implemented traffic control and modal preference in their spatial structure.
- Commonly, the central area is dominated by public transit.

Pendulum Movements:
- Obligatory movements involving commuting between locations of residence and work.
Professional Movements:
- Movements linked to professional, work-based activities such as meetings and customer services, dominantly taking place during work hours.
Personal Movements:
- Voluntary movements linked to the location of commercial activities, which includes shopping and recreation.
Touristic Movements:
- Important for cities having historical and recreational features.
- Involve interactions between landmarks and amenities such as hotels and restaurants.
Distribution Movements:
- Concerned with the distribution of freight to satisfy consumption and manufacturing requirements.

Trip Generation:
- On average, an urban resident undertakes between 3 and 4 trips per day.
- Moving in an urban area to satisfy a purpose such as employment, leisure, or access to goods and services.
Trip Destination:
- Changes in the spatial distribution of economic activities in urban areas have caused important modifications to the destination of movements, notably those related to work.
Modal Split:
- Implies the use of a series of transportation modes for urban trips (modal choice).
- This choice depends on factors such as cost, technology, availability, preference, travel time (distance), and income.
Trip Assignment (Routing):
- Involves which routes will be used for journeys within the city.
- Passenger trips usually have a stable routing.