What roles do lampposts and trees serve in urban mental health?

Marjia Jannati is a junior at Georgetown University pursuing a BSc in International Health. Originally born in Bangladesh she grew up in Pennsylvania and currently lives in  Washington, D.C. She is interested in global development and mental health in conjunction with the urban lifestyle of people living in developing nations. She wrote this piece as part of her work as a UD/MH Research Associate.

Streets account for the majority of our calculated urban space. Defined loosely, the ‘streetscape’ refers to the natural and man-made elements of our streets. The Torbay Streetscape Guidelines elaborates on this simple definition to include: “design quality of the street and its visual effect, particularly how the paved area is laid out and treated. It includes buildings, the street surface, and also the fixtures and fittings that facilitate its use – from bus shelters and signage to planting schemes.” One of the determining factors of a prosperous city is the sustainable design of its streetscapes. However, this prosperity is mostly focused on functionality and often fails to fully leverage the mental impact of design elements on pedestrians and passengers.
 
When looking at the visible landscape, humans can be affected in many ways that encompass aesthetic appreciation, health and wellbeing. Personally I feel more calm and at ease during a walk or drive alongside a stretch of trees and greenery as opposed to towering buildings, blank facades, grey sidewalks and seemingly endless armies of lampposts. Research exploring the health effects of viewing landscapes confirms my experiences, observing that in some instances, the built urban landscape can indeed pose a negative effect on our mental health and wellbeing. For instance, exposure to monotonous features in streetscapes have been associated with sadness, stress, and even addictions. On the other hand, research consistently finds natural landscapes to be positively correlated with mental health and wellbeing, an effect that can be achieved in the urban environment. A recent cross-sectional study examining urban tree density and anti-depressant prescription rates in London, UK identified a decrease of 1.18 prescriptions per thousand population in areas with a per unit increase in trees per km of street. The study suggests that street trees seem to be a positive urban asset that may play a role in preventing and mitigating mental health problems, and a body of research corroborates this finding. Increasing arbor planting can increase sidewalk functionality, but of course it can have practical implications, including the risk of making roadway functionality more difficult. Thus the choice of whether to install urban trees in streetscapes often falls into the hands of citymakers – and lawmakers. Ensuring that these designers, planners and decisionmakers are aware of the population mental health implications of their decisions is important.
 
Streetscapes also have an element of auditory interaction with our senses. Our body is wired in a way in which the function of our auditory reflex is somewhat dependent on the tranquility of our immediate environment. Therefore, when considering soundscape, the visual scene is likely to be an important modifying factor in our auditory perception. An evaluation of the effect of natural sounds in conjunction with road traffic noise and visual components in urban streets concluded that the “acoustic comfort factor related to soundscape quality considerably influenced preference for the overall environment at a higher level of road traffic noise.” The most popular of 'nature sounds' was found to be birdsong. On the other hand the sound of falling water was actually found to reduce the soundscape quality if the road traffic noise level happened to be too high. A mixture of functionality and auditory-visual street features, such as artistic acoustic highway noise barriers will serve well to promote mental wellness as well as providing a system of transport from one location to another.
 
It’s time to recognize that the immediate environment including the often-unwavering streetscape, which we have become involuntarily accustomed to, plays a vital role in shaping a significant part of our mental wellbeing. Along with having street elements, such as road signs, to guide and protect our physical body, we also need to have streetscapes that nourish our mind.

This proposal for an environmentally-friendly acoustic barrier (“Forest Corridor”) in Hong Kong was designed by Bread Studio to meet three conditions: masking the sight of the highway from nearby residential buildings, improving the view of the highway’s underside for people in the park below, and relieving drivers from any claustrophobic impressions as they cruise through the de facto tunnel. - from weburbanist.com