Cities have played a significant role in economic, social, and cultural life since the dawn of time, yet their role has never been as significant as it is today. Observing global trends, two conclusions can be drawn: the urbanization rate is systematically increasing, and cities are becoming larger. Moreover, these trends will continue. Evidence for the validity of these theses is provided by an analysis of data published by the UN. It shows that in the last 30 years, the urbanization rate has risen from 38.9% to 50.5% in 2010, which means that the number of city dwellers has more than doubled, from 1,727 million in 1980 to 3,486 million today. In 2010, there were 21 urban centers with a population of over 10 million and as many as 442 cities inhabited by more than 1 million people. In contrast, 30 years ago, there were 4 and 197 such cities, respectively.
Large cities are accelerators of development for regions and even entire countries. However, the development of every city is limited by the occurrence of various barriers. The most significant groups of barriers are natural and environmental, demographic-social, economic, structural-spatial, technical, and informational. Not every city struggles with all the mentioned groups of barriers, and the scale of limitations resulting from the occurrence of individual barriers is not the same in every center. However, in the unanimous opinion of specialists representing various fields and disciplines of knowledge, who are simultaneously involved in city management, the most common and increasingly significant barrier to their development is transport congestion.
According to A. Altshuler, transport congestion occurs in any situation where “demand for an infrastructure facility prevents free flow at the maximum permissible speed of traffic“. Free flow, on the other hand, should be defined as the flow of vehicles that is not hindered by interactions between vehicles, weather conditions, or other factors that could cause the speed of vehicles to be lower than the maximum permissible speed on a given road section.
The occurrence of congestion causes the emergence of many diverse groups of costs and negative effects or increases their level. The most important include:
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costs of lost time,
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vehicle operating costs,
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costs of environmental pollution,
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accident costs,
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infrastructure costs.
The most severe are the costs of lost time incurred both by users of the city’s transport system – drivers and their passengers – as well as entrepreneurs and institutions using transport infrastructure directly or indirectly using the services of transport, courier, and other companies. The costs of lost time also include the costs of not arriving at the destination on time, primarily the costs of delays. Delays can have far-reaching repercussions; for example, arriving too late for a job interview can affect an entire professional career, and being late for the airport can result in failing to sign a lucrative contract. This also applies to carriers, logistics operators, couriers, and postal services, for whom the untimely delivery of a shipment usually involves the necessity of incurring financial penalties, as well as, which is usually more severe, the loss of credibility and damage to their image in the eyes of the contractor.
Municipal services – including the police and fire department (although their vehicles are privileged, they use the same infrastructure as other users) – in order to ensure a short arrival time at the scene, are forced to operate a larger number of vehicles and employ a correspondingly larger number of people to operate them. Public transport carriers, mainly bus operators (unless special traffic lanes have been designated for their vehicles), face similar problems. To maintain an appropriate frequency of service, they must increase the number of vehicles in operation. Furthermore, low travel speed makes public transport less attractive to passengers, which consequently limits the carrier’s revenue, leading to a further reduction in the competitiveness of their offer. This also leads to an unfavorable feedback loop, as a larger number of vehicles from all the above groups of infrastructure users moving on the roads further increases the level of congestion.
Moving in congested conditions causes an extension of vehicle operating time and, thus, an increase in fuel consumption. Accelerating and braking, sometimes very abruptly, increases the costs of tires, wear of the braking system (brake pads and discs), and the clutch, which is engaged and disengaged many times. Therefore, all the mentioned components require more frequent replacement. Additionally, accelerated wear of braking systems causes an increase in the emission of heavy metals and asbestos, which adversely affect human health, causing an increased incidence of cancer.
Congestion causes a significant increase in the emission of harmful substances, such as nitrogen oxides, particulate matter, sulfur dioxide, carbon monoxide, as well as greenhouse gases – CO2 and nitrous oxide and other compounds that negatively affect human health. Many trips made in the city are performed with a “cold engine,” when it does not reach full efficiency and fuel is burned incompletely, which additionally increases the emission of the above pollutants, in particular carbon monoxide.
The article comes from the magazine “Logistyka” 5/2010.