Visual Pollution

The term visual pollution is usually applied to describe the negative effects of man-made structures on people's perception and enjoyment of the surrounding environment. The concept is subjective, because it depends on one's aesthetic views, but is often related to aspects such as the disruption of visibility, irregular or incoherent patterns, clutter, juxtaposition of different types of visual elements, and predominance of certain shapes and colors.

The transportation system can be an important source of visual pollution. Large transportation infrastructure can have a disruptive presence in the visual environment, especially in the case of elevated highways and railways. Some features of the design of vehicles can also be regarded as visually unpleasant by some people.

Secondary elements in the transportation infrastructure, such as signs and billboards, can also reduce the aesthetic value of the travel experience for users of the infrastructure. The recognition of the negative impacts of transportation in terms of visual pollution has led to the introduction of laws and public policies to limit or to regulate the quantity and type of elements intruding in the landscape. Despite the recognized effects of visual pollution on human well-being, there is still relatively little research or methods for its measurement and evaluation.

Elevated highways have a considerable visual effect on people at street level. Because of their large size, they disrupt the perceptions human beings have of the surrounding environment. This is especially true in the case of major junctions, or areas with multiple elevated highways at different heights. Exposure to these effects can be particularly unpleasant in conjunction with exposures to other types of road pollution, such as air pollution and noise. In addition, measures for mitigating pollution (such as noise barriers) may also contribute to visual pollution due to their size, shape, or type of material used.

The scale of the infrastructure is a crucial factor in the aesthetic experience of people at the street level, as it contributes to the monotony of the visible landscape while they are walking. The size of the road and its position at a higher level can also be intimidating for pedestrians, especially when combined with vehicles at fast speed. The presence of transportation infrastructure also affects people's views from their houses and offices.

Elevated railways have similar visual aspects. The size and position of the infrastructure, combined with the speed of trains and their associated noise and vibration, can be intimidating for the people at the street level and for residents and workers in buildings facing the line.

While most research on visual pollution has focused on the effects of the infrastructure, the traffic on that infrastructure may also have negative effects on the visual environment. In the case of road traffic, important elements include the shape of cars and the reflections from their metallic and curved surfaces and from windshields. These elements can be perceived as alien to the streetscape and, more generally, to the natural and built environments and can be alienating for pedestrians.

This factor may contribute to what some sociologists identify as the unequal relationship of power between car users and pedestrians. When moving at high speeds, vehicles can be intimidating for people at the street level. However, even when parked, cars also can be perceived as a visual nuisance by the pedestrian. Lights from cars can interfere with the pedestrian travel experience and increase pedestrian accident risk when walking along or crossing roads.

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