Social-Economic Effects Of Road Traffic Congestion In Nairobi
Traffic Congestion: Definition and History of Congestion
DefinitionWaweru (2012) defines congestion as a situation where the demand for road space exceeds the supply. This definition makes use of the two central characteristics of congestion, namely: the inadequacy of available road space for use, and the demand. Olagunju (2015) postulates traffic jam is experienced when travel demand is immense enough such that the interaction between vehicles slows the speed of the traffic stream and this is manifested by slower speeds, longer trip times and increased queuing and tailgating (Katala).
FHWA (2017) relates traffic jam to an overflow of vehicles on a section of a road way at a given time which results into speeds that are slower than the free flow speeds. It means stopped or stop-and-go traffic.
ECMT (2007) simply defines congestion simply as a situation in which demand for road space exceeds supply. This defination is often used by transport engineers in a bid to solve congestion issue by expanding/upgrading roads or better still constructing new roads all together.
Congestion is not a new occurrence but predates the industrial revolution, the motor vehicle and modern city. Before the automobile era, traffic jam was characterized by stagecoaches, wagons, and pedestrians contending for business district (CBD) space. Initially road network in urban areas was designed for walking. Eventually however, towns grew and others means of transport such as horse buses, trams, trolley buses and motor buses were introduced and used the same road space causing congestion. Since there were limited public spaces, roads became areas of concentration for employment, housing and community facilities causing more congestion.
Morris (2014) concedes that traffic congestion has plagued man all the way back to ancient Rome where the major causes of traffic were the high population density, the organic street network, narrow streets, the street being used for non-transportation activities and obstacles (stones) placed on the road to avoid stepping in the muck. He further observed that the ancient equivalents of transportation planners and engineers did their best to overcome these problems by banning wheeled traffic within the City during certain hours of the day, requiring the travelers to dismount and walk through city limits and blocking certain streets from vehicular travel. However, little success was achieved from these endeavors.A review by the Commission for Integrated Transport shows that UK is one of the most congested European countries and can be attributed to the fact that road traffic is growing faster than the road capacity
Congested Links in the UK
According to a survey done by UN-HABITAT, congestion on roads is the major type of infrastructure insufficiency (96 per cent in Africa; 91 per cent in Asia; 88 per cent in Latin America; and 80 per cent in Arab states) plaguing cities in both developed and developing cities hence hampering free movement and increasing travel times. Defective roads in most African cities hinders free movement and prosperity and are a major cause of traffic congestion. This is aggravated by the poor road maintanance since only 18.5 per cent of experts across African cities believe that infrastructure is systematically maintained
Urban Transport Economic Theory
The many activities and interactions in urban areas result into a variety of externalities which in return make’ pricing’ of transport cost difficult. Transportation costs play a critical role in the formation and working of cities. Some the externalities include; traffic congestion, environmental pollution, accidents, noise among others. The Federal Highway Administration in USA estimates the average cost of the externalities. To calculate the private and social costs incurred in terms of vehicle running costs (fuel. Tires, engine oil, wear and tear etc), cost of time and traffic accidents cost a basic model that examines travel on a single point-input, point-output road is used. The assumption is that drivers are identical, and the only decision each makes is trip frequency and congestion is captured by a congestion cost function that relates trip cost to travel flow and capacity.
Basic model of Urban Transport Economic Theory
According to Arnott (2001), the APC curve slants upwards due to congestion because as traffic flow increases so does the trip time and trip cost. With no intervention from the relevant institutions, the equilibrium where the Demand curve (D) will meet with the User Cost curve (APC). On the other hand, the optimum will occur where Demand curve (D) meets the Marginal Social Cost curve(MSC).
When an individual driver takes an extra trip by slowing other drivers down, it imposes external congestion cost which is the APC and MSC. To spread out the social optimum, the relevant institution can enforce a congestion toll, t, in the diagram, equal to the marginal external congestion cost, evaluated at the socially optimal level of flow.
However, the Economic theory has been criticized by, among others Richard Arnott, on the following basis:
- Many relevant margins of choice are ignored: The essential features of most policy problems can be captured by considering only a small number of margins of choice.
- The congestion function captures not only technology but also behaviour: Economic model treats the congestion function as being determined by technology, but in fact the congestion cost function incorporates all the behavioral decisions related to travel as well.
- Link flow congestion is not the only form of congestion: the model treats only one form of congestion: link ﬂow congestion, in which a driver’s travel time and travel costs on a link are positively related to traffic volume or ﬂow on the link
Von Bertalanffy, the founder of the theory, was both reacting against reductionism and attempting to revive the unity of science. He emphasized that real systems are open to, and interact with, their environments, and that they can acquire qualitatively new properties through emergence, resulting in continual evolution.
According to Agyemang (2009), studies of systems have always tended to address four key issues:
- Whether a system is closed i.e. has no links to or from a surrounding environment or open (i.e. have and interact with the milieu).
- Whether the system can be divided into subsystems, or clusters of interdependent elements which are only weakly-linked to the remainder of the system.
- Whether the links involve flows, causal relationships or ‘black-box’ relationship (in which the consequence of the link is known but the causal factors are not).
- Whether there is a feedback in the system such that change in x may stimulate change in y, and this will in turn have an impact on x, either positive or negative.
Agyemang (2009) used the general systems theory to analyze the urban transport system and identified three key subsystems namely; land use, transport supply and traffic:
- Land use may be seen as the legal use of land, the type of structures and socioeconomic activities.
- Transport supply refers to the capacity of transportation infrastructures and modes and can be expressed in terms of infrastructures (capacity), services (frequency) and networks. The number of passengers, volume (for liquids or containerized traffic), or mass (for freight) that can be transported per unit of time and space are commonly used to quantify transport supply.
- Traffic is a direct function of land use and urban transport system is seen as a sub-system which is an integral part of the much wider urban system.
The systems theory has received its share of criticisms by renowned scholars, especially Giddens (1984), who for instance, criticizes the theory for what he refers to as its ‘empire-building endeavors by emphasizing the pre-eminence of the social whole over its individual parts. Also, in line with hermeneutic tradition, he regards the social and natural sciences as radically discrepant.
The structuration theory was proposed by sociologist Anthony Giddens in his book “the Constitution of the Society” which examines the phenomenology, hermeneutics and social practices at the inseparable intersection of structures and agents.
Structuration theory is based on the premise that the classic actor/structure dualism has to be reconceptualized as a duality. He, therefore, draws attention to the fact that structure must be viewed as the ‘structuring properties allowing the binding of time-space in social system, the properties which make it possible for discernibly similar social practices to exist across varying spans of time and space and which lend them ‘systemic’ form’. Therefore, in his view, ‘those practices which have the greatest time-space extension within such totalities can be referred to as institutions’. Structuration theory is based on the proposition that ‘structure is always both enabling and constraining, in virtue of the inherent relation between structure and agency.
Those who have resources can mobilize power, although power itself is not a resource but the result of possessing material and organizational facilities. Rules and resources are “transformational” in that they can be created, changed, and recombined into different forms; also, they are “mediating” in that they are what actors use to tie social relations together.
This study finds some elements of the structuration theory quite useful and contextualizes the theory to Kenyan Transport System consisting of various actors who in one way or the other use their ‘power’ through policies to influence decisions on the transportation sector.The supply of transport is limited to a large degree by the existing structures or resources available to the provider (the Nairobi City County as well as the National Government). Provision of roads as well as their maintenance has become a political affair not only in the City Capital but also across the country with promises to ‘reduce traffic jams during campaigns’ by the City County politicians only for their term to end without any change.
The structuration theory has not gone without scathing criticism. John B. Thompson, draws attention to the ‘looseness’ of the Gidden’s explanation of structures as rules and resources and argues that he has not provided adequate account that will make it ‘useful and satisfactory to identify social structure with rules (and resources)’. Other critics, such as Archer (2004) and Parker (2000) believe that ‘the moment of structuration theory passed some time ago’.
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