Traffic congestion, its causes and health hazards in the environment

Introduction

Road traffic congestion can be described as a physical phenomenon relating to the manner in which vehicles impede one another’s progression as demand for limited road space approaches full capacity. Traffic congestion then occurs when too many vehicles attempt to use common infrastructure with limited capacity (Commuter Pain Survey, 2009).

Traffic congestion occurs when there is excess demand on a highway or road, or when the actual number of vehicles on the road is greater than the capacity of that road to maintain effective traffic flow. Slow speeds, longer trip times, and increased queuing of vehicles characterize traffic congestion (Altshore, 2007). A period of extreme traffic congestion is also known as traffic jam or gridlock. Gridlock is a term used in describing an ability to move on a transport network. The term originates from a situation in a grid network where intersections are blocked, preventing vehicles from either moving forward or backward through the intersection or backing up to an upstream intersection (Oni, 2010).

According to Carlos (2009), recurrent congestion is generally the consequence of factors that act regularly or periodically on the transportation systems, such as daily commuting or weekend trips. However, even recurrent congestion can display a large degree or randomness, especially in its duration and severity. For example, there are roads that are congested early in the morning when workers are resuming for work. Others are busy in the evening, when workers return home while Armah, Yawson and Papson (2009) noted a myriad challenges to transportation system in relation to negative extremity such as traffic congestion and environmental risk. However, the fact that cars has brought freedom, flexibility and mobility to many people it cannot be overlooked, but there is increasing concern about the health and environmental impacts of pollution from congested traffic. The same forces that draw inhabitants to congregate in large urban areas lead sometimes to intolerable levels of traffic congestion on urban streets and thoroughfare.

Also, rising incomes combined with an increasing propensity from personal mobility and inadequate mass transportation on facilities has resulted in a pronounced increase in automobile ownership and its utilization in major cities. The emergence of traffic and subsequent traffic congestion has opened up the need for improved traffic flow to ensure reduced travel time, safety, average fuel consumption and healthy environments (Ferguson, Mahiswalis & Dalu, 2014).

Conceptual framework

According to Organization for Economic Co-operation and Development (OECD, 2007), there is no single broadly agreed definition of traffic congestion due to the fact that it is both a physical and a relative phenomenon. As a physical phenomenon traffic congestion can be defined as situation where demand for road space exceeds supply and is reflected by slower speed, longer trip times and increased motor vehicular queuing. As a relative phenomenon, O.E.C.D (2007) went further to state that it can be seen as a difference between road performance and road user’s expectations. This view was also supported by Aderamo (2012).

In the opinion of Remi, Adegoke and Onyerinde (2009), traffic congestion is when vehicles travel at slower speeds because there are more vehicles than the road can handle. This makes trip times longer, and increases queuing. This is also known as a traffic jam. Congestion may result from a decrease in capacity, for example accidents on the road or roads being closed. Bad road layouts can also restrict capacity. Increased traffic, for example by many cars leaving a sports stadium at the same time, can also cause congestion.

Traffic congestion is a problem in many cities of the World, both in developed and developing countries and it is predicted that it will get worse in the future (Jain, Sharma & Subramanian, 2012). According to

Lupala and Kiunsi (2011), traffic congestion can be viewed from two main opposing perspectives. The first perspective is that it can be considered is an indicator of economic growth and as long as we live in urban areas it is here to stay with us. The second perspective is that congestion as an indicator of deterioration of urban life. Urban traffic congestion can be contributed by a number of factors including rapid increase in urban population, economic growth, increase in employment opportunities, increase in number of cars and number of people using cars, low capacity of transport infrastructure, road layout, under investment in road infrastructure, poor traffic management, shortage of street parking, signal and equipment failure, non adherence to traffic regulations, poor urban planning or poor urban development control, rapid expansion of city boundaries, poor public transport, increased use of private cars, car accidents, special events gatherings, road works, and bad weather (Agyemang, 2009).

Types of traffic congestion on roads

According to Opeyemi and Joseph (2009) road traffic congestion can be grouped into two broad types, which are:

1. Recurrent traffic congestion
2. Non- recurrent traffic congestion

1. Recurrent traffic congestion

Recurrent traffic congestion is usually common among residents and commuters living in urban areas. This is referred to as a situation where traffic congestion is experienced on a daily basis.. Recurrent traffic congestion occurs on a daily basis during “peak-hours” or “rush-hours” which are between 6 a.m. and 9 a.m. and again between 4 p.m. and 7p.m. (Opeyemi & Joseph, 2009).

According to Shah and Dal (2007), the reasons why people travel in these time frames may vary on a case by case basis, but it is seemingly obvious that a major cause of the peak-hour traffic is because many employers require employees to start between 8 a.m. and 9 a.m., with the work day ending between 4 p.m. and 5 p.m. However, peak-hour travel is reinforced by other human tendencies as well, including school schedules. They further stated that recurrent traffic congestion is associated in mismatch between growth in population and infrastructural development of an area.

2. Non- recurrent traffic congestion

Unlike recurring congestion, non-recurrent congestion is usually unexpected. Opeyemi and Joseph (2009) define non-recurring congestion as unexpected traffic delays caused primarily by crashes and incidents, vehicle breakdowns, road construction activities, special events, extreme weather events, etc. Any of these events or the combination of these events can cause free-flowing traffic to suddenly slow movement of vehicles causing congestion. Non-recurring traffic congestion is worst in areas with poor emergency preparedness plans and lack of emergency mitigation systems and absence of traffic detours.

Factors responsible for traffic congestion in Nigeria

There are numerous factors responsible for traffic congestion in Nigeria. According to Ogunleye and Ibitoye (2006), some of the causes of traffic congestion in Nigeria include:

• Accidents
• Disabled vehicles
• Construction Work
• Events that draw large crowds
• Inclement weather
• Poor traffic management
• Drivers misbehaviour

1. Accidents: The occurrence of road accident has led to traffic congestion as this congestion blocks one or more road traffic lanes since in most cases, motorists are not been able to use the lane where there is accident occurrence. The presence of rescue worker and sympathizer can also make the case worse by further limiting the accessible routes for motorists as a result limit the free flow of traffic through the road hereby leading to road traffic congestion (Ogunleye & Ibitoye, 2006).
2. Disabled vehicles: Broken down or dilapidated vehicles on the road cause road traffic congestion because this lead to reduction in the number of vehicle that can pass through the road at a particular period of time. For example, cases where disable vehicles are repaired on the main road or their owner are awaiting towing vans causes serious road traffic congestion especially in a very busy route (Ogunleye & Ibitoye, 2006).
3. Construction work: Ongoing construction can restrict the rate of movement of vehicle on a particular road or outright closure of road leading to detour of traffic to an adjourning route. In most cases, the adjourning route is compelled to handle more traffic than its usual capacity leading to traffic congestion (Ogunleye & Ibitoye, 2006).
4. Events that draw large crowd: Events that draw large crowds to a particular location such as church programmes, football match, burial ceremony, etc is usually associated with high volume vehicular movement towards a particular point which usually lead to the presence of more traffic than what can be handled by the road leading to traffic congestion (Aderamo, 2012).
5. Inclement weather: Inclement weather such as snow fall, heavy rainfall, fog, etc. can lead to poor visibility and drivers usually have to drive slowly due to poor visibility in order to avoid traffic accident. In this situation especially for routes that handle heavy traffic, traffic congestion is usually very common (Aderamo, 2012).
6. Poor traffic management: The poor traffic management is a result of malfunctioning of traffic lights, absence of road signs, inadequate enforcement of laws, low penalties given to punish violators of traffic congestions, employment of few law enforcers for instance traffic police and lack of facilities to tow disable vehicles on the road. This is also a problem in other developing countries like Nigeria whose economy is weak. As a result, they cannot afford to control traffic using modern technology which is rather expensive in terms of resources (Aderamo, 2012).
7. Drivers misbehaviour: Nigeria is one of the countries which are highly characterized by reckless driving due to violation of traffic rules. Drivers have a tendency to disregard or violate the traffic regulations such as; to overtake where it is prohibited, driving while drunk, neglecting road signs and markings, discharging of passengers on the road instead of the bus stop and the use of the U-turn where is prohibited. Drivers may lack confidence or ability due to poor training as well as lack of competencies. Thus, misbehaviour of some drivers on failure to adhere to traffic regulations is among the main contributing factors to the increase of traffic congestion (Aderamo, 2012).

Modes of urban transportation in Nigeria

With respect to urban road transportation in Nigeria Igwe, Oyelola, Ajiboshin and Raheem (2013) stated that it is important to evaluate the extent and quality of the road network. Poorly-maintained roads are particularly problematic in the rainy season (approximately March to October). In fact, some areas are only accessible by car in the dry season due to poor road network or poor constructed and managed roads thereby contributing to heavy traffic in the few good roads leading to traffic congestion (Odeleye, 2008).

Taiwo (2010) stated that many roads in urban Nigeria cannot be safely travelled at speeds exceeding 50 to 80 kilometres per hour. The slow rate of travel is necessary given the large and frequent pot holes that mark the many urban roads. Certain stretches of urban roads in Nigeria in the assertion of Taiwo (2008) are so bad that motorized vehicles have bypassed the original roadway to form new dirt tracks. Other portions of urban roads have been reduced to one lane.

In buttressing his point on poor road maintenance in urban centres in Nigeria, Oni (2010) stated that although almost all urban roads are paved (Nigerians often say “tarred”), many have large pot holes or large sections where pavement has been eroded. An interesting scene in some roads in urban centres in Nigeria is the activity of informal road repair crews. Young men can often be seen filling city pot holes with dirt and rocks. In return for their unsolicited service, road users often tip these unofficial public workers. The work of these brave maintenance crews notwithstanding, Nigerian urban roads can still be very rough. The important point to note is that aside from uncomfortable travel, poor urban roads can cause bottlenecks in traffic and contribute to traffic congestion.

Another issue that directly relates to urban transportation is city planning. While the extent and effectiveness of planning in Nigerian cities varies to some extent, most urban areas are forced to deal with city regions where no formal planning was conducted. Hence, transportation routes are often confined to pre-existing routes that may not always follow optimum courses. Oni (2010) added that one other aspect of Nigerian urban transportation is the notable lack of public transportation. While there have been several different programs and agencies established in the post-1988 period, government efforts to provide public transportation have been mostly failures.

Relationship between road safety and traffic congestion

Traffic congestion is associated with several negative consequences on the quality of people’s lives. Road users experience delay and stress and environmental pollution increases (more noise, more emissions and more fuel consumption). The effects of traffic congestion on traffic safety, however, are less obvious.

Rietveld  and Shefer (1994) suggest that congestion might have a positive effect on safety by decreasing the number of fatalities as speeds decrease. Although this statement seems logical, when looking at the traffic conditions in more detail the effects of congestion on safety are less apparent. As traffic flow increases and density approaches its critical value, traffic flow is said to be unstable. Under these conditions, any small disturbance may lead to crashes. Once the traffic jam is formed, rear-end crashes may occur at the tail of the queue due to large differences in speed. Furthermore, motorways giving evidence of structural congestion (i.e. there where demand is almost always higher than capacity) cause road users to seek alternative routes – often perceived as faster routes – which are almost inevitably roads with a higher accident risk.

It is important to gain a clear understanding of how traffic flow processes affect safety, in order to better understand developments in traffic safety and in order to identify possibilities for improvement. This report focuses on the effects of unstable and congested traffic situations on traffic safety. Factors such as the location of queues, variable message signs or automatic incident detection might play an important role in the relationship between traffic safety and congestion.

Policies on traffic congestion

Traffic congestion policies in Nigeria are classified into three main policies: governmental policy to control increment of cars number and encouraged public transportation, travel demand management to contain the potential increase number of cars, and supply management by good transportation planning.

The Federal Road Safety Corps (2013) stated that traffic congestion policies in Nigeria is aimed at reducing waiting time and number of vehicles at route intersection to manage traffic replacement of un-signalized intersection either signalised intersection.  In order to reduce traffic congestion, air pollution and enhancing safety in many industrialized and commercial areas using Intelligent Transportation Systems (ITS).

Traffic congestion identification is an important issue for intelligent transportation system in order to identify traffic congestion. The traffic congestion identification method combines principle component analysis (PCA) and compensation of advanced travail information system (ATIS) and road pricing technologies to reduce traffic congestion and travel time.

Impact of traffic congestion

According to Arman, Yawson and Papson (2009), the impact of traffic congestion can be classified into:

1. Impact on human’s health
2. Impact on nature (environment)

Impact of traffic congestion on human health

• Physical impact on health
• Impact on mental health
• Physo-social impact

Impact on health

Traffic congestion is becoming an increasing source of air pollution. First, traffic congestion increase emissions; motor vehicles emerged as the greatest contributor to atmosphere warming as cars, buses and trucks release pollutants and green house gases that promotes global warming. Traffic congestion makes motorist to inhale vehicular smoke emission resulting into diseases (Ferguson, Mahiswalis & Dalu, 2014). Carlos (2009) opined that inhalation of particulate matter is associated with increase in people with asthma, reduction in lung function and admission to hospital for respiratory and cardiovascular diseases.

Ferguson, Mahiswalis and Dalu (2014) also agreed that air pollution has been lined to morbidity and mortality from various diseases such as coronary disease, aggravation of respiratory disorder and obstructive pulmonary diseases. It is in relation to nasal and ocular symptoms that vehicle exhaust fumes probably have their greatest effects.

Impact on mental health

Road traffic congestion creates mental stress. Stress can be caused by the amount of traffic congestion resulting into road rage and has become an increasing social problem. It has been the cause of many attacks on car drivers and has even resulted in several deaths. Disorders attributable to stress includes hypertension, headache, backache, skin disorder, irritable bowel syndrome and ulcers. Stress is also believed to contribute to coronary heart disease and some case of cancer (Anerbach & Cabling, 2007).

Stress can also contribute to some respiratory disorder. For example, stress can trigger asthma while proximity to traffic was recently reported to be associated with wheeze in infants; air pollution related to traffic is significantly associated with triggering of wheezing symptoms in the first three (3) years of life (Anerbach & Cabling, 2007). Almost one in three drivers suffers from a newly recognized disorder, named “Traffic Stress Syndrome”. This is a form of psychological anxiety that certainly affect drivers, while stuck in traffic. Symptoms normally show after being held up in traffic. It is characterized by increased heart rates, headaches,

and sweaty palms. In more severe cases, drivers report nausea, dizziness and stomach cramps. The impact of these symptoms can lead to a loss of concentration and poorer driving as well as heightened levels of anger (Commuter Pain Survey, 2009).

Psycho-social impact

The fact that many of our roads have failed to keep pace with a growing population and increased travel demand, traffic congestion has continued and also economic and social development and also has a negative impact on the environment (Kakooza, Mouguisha & Luboobi, 2005). Traffic congestion result in longer travel times, extra fuel consumption, high-level pollution, discomfort to road users, and degradation of the urban environment (Ellimah, 2009).

Busy streets mean that children are discouraged from playing on road or from walking or cycling to school. Besides, there are environmental, societal and business challenges caused by traffic congestion such as tiredness, resulting into weariness of drivers, which has led to road accident. When employees are stuck in traffic, the tiredness and the stress has also resulted to low productivity (Commuter Pain Survey, 2009). In addition, congestion reduces regional economic health because traffic congestion is proving to be a major cost and inconvenience for many businesses and companies particularly those whose activities demand high level of transport per unit of production.

Traffic congestion has an impact on a large proportion of companies to a major degree particularly, when one consider the road haulage cost, delivery schedule from the company and staff punctuality. Delays, which mainly result in late arrival for employment, meetings, and education, resulting to lost of business, disciplinary action or other personal losses and wear and tear on vehicles as a result of idling in traffic and frequent acceleration and braking, leading to more frequent repairs, and replacement of parts results into financial burden on the individual and the nation at large (Ellimah, 2009).

Impact of traffic congestion on nature (environment)

Traffic congestion and delays causes increase in auto emissions such as CO₂ and different poisonous hydrocarbons.  These pollutants caused many cities’ ambient air to be unsafe. The environmental impact of traffic congestion is significant because it is a major user of energy, and burns most of the petroleum products used. This creates air pollution, including nitrous oxides and particulates, and is a significant contributor to global warming through emission of carbon monoxide.

Other environmental impacts of transport systems include traffic congestion and automobile-oriented urban sprawl, which can consume natural habitat and agricultural lands. By reducing transportation emissions globally, it is predicted that there will be significant positive effects on Earth’s air quality, acid rain, smog and climate change (Oni, 2010).

Measures to minimize traffic congestion in Nigeria

According to Aderamo (2012), the problems of traffic congestion in Nigeria can be addressed through proactive and congestion management strategies to control traffic movement in our cities and on the major highways. These measures include:

• Research
• Highway construction
• Traffic monitoring
• Changing the way we use the road
• Control of traffic at construction zone
• Proper road transport regulation
• Separating city from inter-city traffic
• Traffic management
• The use of public transit

1. Research: Research into the causes of congestion in different parts of the cities and on different corridors is necessary since different areas could present unique situation requiring different solutions. The mistake many city authorities make is the belief that they can replicate solutions that worked in other areas such as the climate without conducting any study to determine the suitability or that the same strategy is applicable in every part of the city (Oyeyemi, 2015).
2. Highway construction: Highway construction and other transport infrastructure in the cities should be continually expanded as efforts should be made to attract local and international financing. This will reduce traffic congestion (Aderamo, 2012).
3. Traffic monitoring: Installation of traffic sensors to alert relevant authorities on abnormal flow or obstructions could aid prompt mitigating responses before congestion actually occurs (Aderamo, 2012).
4. Changing the way we use the road: Motorists, motorcyclists, bicyclists and pedestrians need clear and traffic guidance through built up areas such as work zones. This will eliminates traveller’s confusion that can lead to crashes which creates traffic problems (Aderamo, 2012).
5. Control of traffic at construction zone: There should be proper traffic control at construction zones in the cities and on major corridors where road rehabilitation activities are ongoing (Aderamo, 2012).
6. Proper road transport regulation: There is also the need to properly regulate activities of transport operators to ensure that they abide by all laid down traffic guidelines (Aderamo, 2012).
7. Separating city from inter-city traffic: It is always better to have road developments where those who have no businesses in the cities can always use bypasses so that they don’t add to the urban traffic (Aderamo, 2012).
8. Traffic management: Indiscipline is another factor of traffic crises in our cities and on our roads. Oyeyemi (2015) believes that enforcing traffic laws strictly without fear or favour will enhance the liveability of our cities. Proper planning of transportation in the cities entails understanding the dynamics of the transport demand and supply.
9. The use of public transit: The use of public transport services should be encourage as this will reduce the number of vehicles plying the road since public transit can convey a large number of people in a single trip thereby reducing the number of vehicle on the road and subsequently, traffic congestion (Aderamo, 2012).

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