Impacts of Road Traffic

Introduction

Since 1975/6, there has been an increase in the proportion of journeys travelled by car and the distance that people travel. Associated with these rising figures has been an increase in the pressures due to transport placed upon the environment and society.

Congestion

Congestion in cities is acknowledged as a major problem throughout the world. No large city seems to have escaped peak period congestion. It is a problem in countries with generous road systems and low resident densities like the US, as well as in countries like Turkey and Poland, with relatively low levels of car ownership, but poor road infrastructure.

Stress

Stress due to traffic congestion has now taken on the name "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. Stress can also be caused by the amount of traffic on the roads and is a factor in work related sickness leave.

Work and Economic Loss

Rising volumes of road traffic have caused a decrease in the efficiency of delivery services that depend on transport. There is also the problem of rising transportation costs due to increased journey times and hence higher payments for drivers.

Local Air Quality

Transport is becoming an increasing source of air pollution. The transport related problems experienced now are likely to worsen according to the projected increase in UK traffic. The Department for Transport predicts an increase in vehicle traffic of between 17 and 22% by the year 2010, depending on the success of the Government's 10 Year Plan.

The motor vehicle engine emits many types of pollutants including nitrogen oxides (NOx), volatile organic compounds (VOCs), carbon monoxide (CO), carbon dioxide (CO₂), particulates, sulphur dioxide (SO₂) and lead. The table below shows the UK emissions of these pollutants in 1995. Individually, a vehicle engine is not a particularly important source of pollution. Collectively however, vehicles represent a major source of air pollution in the UK.

Table 1: Emissions from road traffic in the UK, 1999

Emissions are related to the use of the engine, mainly the fuel type and the temperature of combustion. If the engine is 100% efficient, then the products of combustion will be CO₂ and water (H₂O). Impacts of transport on the environment include acid deposition (acid rain), human health effects, global climate change and noise pollution.

Carbon Dioxide and Global Warming

Carbon dioxide (CO₂) is a greenhouse gas that is produced naturally through respiration, decay of plant and animal matter and natural forest fires. Man made sources of CO₂ include fossil fuel combustion, deforestation and the manufacture of cement. The main removal processes for CO₂ include its absorption by the oceans and photosynthesis by plants.

Since the Industrial Revolution, concentrations of CO₂ have largely increased. They are higher now than at any other time in the last 160,000 years. The extra amounts of CO₂ in the atmosphere enhance the Earth's natural greenhouse effect, contributing towards global warming.

Of the United Kingdom's total man-made carbon dioxide output, transport accounts for almost a quarter. The UK is responsible for about 3% of the total CO₂ output world-wide, and it is believed that motor vehicles contribute between 14 and 17% of the world's total CO₂ emissions. This figure is likely to increase in the coming years.

The focuses of efforts to reduce CO₂ are on road transport, as it constitutes the main share of the transport market. Other forms of transport, such as aviation, are also considered to represent a growing contribution to the problem of CO₂ emissions and global warming.

Any action that governments may take to decrease the problem of CO₂ emissions from road transport will inevitably lead to some conflicts of interest. For example, the building and use of a new town by-pass may cause considerable environmental damage, but can alleviate town centre congestion.

Some environmental objectives may also have conflicting effects. For example, air pollution is reduced by the use of catalytic converters, but these devices also slightly decrease the efficiency of fuel, thereby increasing the emissions of carbon dioxide.

The best way to reduce the threat of global warming is to use less fuel, and consequently governments are promoting better fuel efficiency. A large amount of transportation takes place on roads, and so this will be the target of most policies. In addition, individual car users have control of how fuel is used. Individuals, therefore, can make a large contribution to the attempts to decrease the man-made enhancement of the greenhouse effect.

If the present rise in the global population is accompanied by economic growth and increased personal income, the total number of motor vehicles could be set to rise beyond 1 billion by 2025, discharging as much as 1,800 million tonnes of carbon into the atmosphere per year. This would be the equivalent over one quarter of the 6,800 million tonnes of carbon emissions from all sources today. Without a major improvement in fuel efficiency, a considerable increase in fuel consumption, and consequently greenhouse emissions, will occur.

Accidents

Although traffic has grown substantially in recent years, the number of road casualties is declining. In 1998, 3,421 people were killed on roads in Britain, compared to 5,526 in 1955 and nearly 8,000 in 1972.

Each year in the European Union (EU) 50,000 people are killed on the roads. Casualty rates vary from country to country for a variety of reasons. There is a tendency for countries with low car ownership to have high death rates per vehicle.

It is also a fact that walking and cycling are less safe forms of transport than cars and buses.

In relation to the amount of time spent travelling, the risk of having a fatal or serious accident is approximately twice as likely on a bicycle as in a car. However, in the majority of cases, injuries or deaths to cyclists are caused by accidents involving cars.

Whilst road death rates are unacceptably high, particularly for pedestrians in urban areas, they are declining in most Western industrialised countries.

Countries like Denmark and the Netherlands make better provisions for cyclists and walkers, which serves to decrease the risk of accidents due to vehicles and cyclists sharing the same road space. Cyclists should also be encouraged to wear a helmet at all times to decrease the severity of any accident that they may be involved in.