This is why pedestrians and cyclists disappear when it starts getting dark

Where did everybody go? Darkened London streets, 1929 vintage. Image: Getty.

Picture the scene: it is 5:30pm on a Tuesday at the end of October, and the streets are full of people walking and cycling home from work. The following week, at the same time, the number of walkers and cyclists has dropped by almost half. The only difference is the clocks have moved back one hour to mark the beginning of Daylight Saving Time.

Naturally, the number of people walking or cycling varies greatly at different times during the day. But twice every year, when the clocks change, researchers like myself get a rare opportunity to compare numbers of pedestrians and cyclists in the same hour of the day, but under different lighting conditions. This enables us to measure the impact that darkness has on how people choose to get around, while other influential factors such as the reason for travelling or the temperature remain largely unchanged.

Using open-source data from automated pedestrian and cyclist counters in a United States district, my colleagues and I analysed the number of pedestrians and cyclists in the same hour of the day, over a two-week period, both before and after the clocks changed.

Darkness effectively reduced the volume of pedestrians by 38 per cent and the volume of cyclists by 27 per cent, after taking into account any changes unrelated to light conditions.

Night and day

There are a number of reasons why people might prefer not to walk or cycle after dark. It’s more difficult to see the path when it’s dark and harder to spot potential trip hazards. Pedestrians have to spend more time looking down and are also less likely to be able to detect obstacles.

Darkness also makes it more difficult for walkers and cyclists to be seen by other road users. As a result, pedestrians are 1.7 times more likely to be hit by a vehicle while using a pedestrian crossing at night, compared with during the day.

Example pedestrian crossing in daylight (left) and after-dark (right). Image: author provided.

Another reason people may not choose to walk or cycle when it is dark is because they feel less safe. One theory suggests that people assess the safety of an environment based on three things: the ability to see clearly for a distance, the presence of features which could conceal a threat and the potential to escape from the area. Therefore, most places are likely to feel less safe at night, because we cannot see as well in the dark.

Fighting the darkness

Ideally, people should be encouraged to walk or cycle, even when it turns dark, because of the huge potential health and environmental benefits. Of course, networks of public street lights have been combating darkness in cities since the 19th century, following the discovery of coal-gas as an illuminant by Scottish engineer William Murdoch. Smoking his pipe beside a fire one night, Murdoch decided to put coal dust in the pipe and put it in the fire. The bright flame that emerged from the mouthpiece prompted the revelation of using gas as a light source.

William Murdoch, pioneer of street gas-lighting. Image: Wikimedia Commons.

But it’s increasingly important to use street lighting effectively to avoid wasting energy and creating needless light pollution, which can have negative effects on plants and animals. To that end, lots of research has been carried out to pinpoint the perfect level of lighting, which still enables pedestrians and cyclists to see effectively without wasting any energy.

Current guidelines for street lighting recommend average light levels of two to 15 lux, depending on the type of street. The evidence supporting these guidelines may be flawed however. The 2.5 GWh of energy used by street lighting every year may therefore be misplaced.

Laboratory research has been conducted to measure the impact of light spectrum and intensity on a pedestrian’s ability to detect a trip hazard. The study found that people are able to perceive a hazard with just two lux of illuminance. When the light was brighter than this, people did not get any better at detecting hazards.

The research also found that white light can be used at lower intensities, without affecting pedestrians’ visual performance. Similar results were found for cyclists’ ability to detect hazards.

Experimental apparatus to assess effect of lighting on cyclists’ detection of a hazard in the road (Fotios, Qasem, Cheal & Uttley, 2017).

Building on work carried out in the US at the end of the 1990s, our team at Sheffield University is also trying to identify lighting conditions which help people feel safe on the streets at night. The US research, carried out in parking lots, found that people felt safer when lights were brighter but that the benefits did not increase correspondingly as brightness increased. We are now verifying these findings on residential streets.

The change of the clocks every autumn – and the earlier onset of darkness – serves as a reminder of how significant daylight is to people’s everyday behaviour, particularly the way they choose to travel. Lighting can help us continue our day-to-day lives even when the sun goes down – and in this new age of highly controllable and efficient LED lighting it is tempting to assume “the more light the better”.


The ConversationIdentifying lighting conditions that meet our requirements without being excessive can help us save energy, reduce carbon emissions, reduce the ecological impact of our lighting and even make astronomers happier.

Jim Uttley is a postdoctoral researcher in lighting & environmental psychology at the University of Sheffield.

This article was originally published on The Conversation. Read the original article.

 
 
 
 

A growing number of voters will never own their own home. Why is the government ignoring them?

A lettings agent window. Image: Getty.

The dream of a property-owning democracy continues to define British housing policy. From Right-to-Buy to Help-to-Buy, policies are framed around the model of the ‘first-time buyer’ and her quest for property acquisition. The goal of Philip Hammond’s upcoming budget – hailed as a major “intervention” in the “broken” housing market – is to ensure that “the next generation will have the same opportunities as their parents to own a home.”

These policies are designed for an alternative reality. Over the last two decades, the dream of the property-owning democracy has come completely undone. While government schemes used to churn out more home owners, today it moves in reverse.

Generation Rent’s new report, “Life in the Rental Sector”, suggests that more Britons are living longer in the private rental sector. We predict the number of ‘silver renters’ – pensioners in the private rental sector – will rise to one million by 2035, a three-fold increase from today.

These renters have drifted way beyond the dream of home ownership: only 11 per cent of renters over 65 expect to own a home. Our survey results show that these renters are twice as likely than renters in their 20s to prefer affordable rental tenure over homeownership.

Lowering stamp duty or providing mortgage relief completely miss the point. These are renters – life-long renters – and they want rental relief: guaranteed tenancies, protection from eviction, rent inflation regulation.

The assumption of a British ‘obsession’ with homeownership – which has informed so much housing policy over the years – stands on flimsy ground. Most of the time, it is based on a single survey question: Would you like to rent a home or own a home? It’s a preposterous question, of course, because, well, who wouldn’t like to own a home at a time when the chief economist of the Bank of England has made the case for homes as a ‘better bet’ for retirement than pensions?


Here we arrive at the real toxicity of the property-owning dream. It promotes a vicious cycle: support for first-time buyers increases demand for home ownership, fresh demand raises house prices, house price inflation turns housing into a profitable investment, and investment incentives stoke preferences for home ownership all over again.

The cycle is now, finally, breaking. Not without pain, Britons are waking up to the madness of a housing policy organised around home ownership. And they are demanding reforms that respect renting as a life-time tenure.

At the 1946 Conservative Party conference, Anthony Eden extolled the virtues of a property-owning democracy as a defence against socialist appeal. “The ownership of property is not a crime or a sin,” he said, “but a reward, a right and responsibility that must be shared as equitable as possible among all our citizens.”

The Tories are now sleeping in the bed they have made. Left out to dry, renters are beginning to turn against the Conservative vision. The election numbers tell the story of this left-ward drift of the rental sector: 29 per cent of private renters voted Labour in 2010, 39 in 2015, and 54 in June.

Philip Hammond’s budget – which, despite its radicalism, continues to ignore the welfare of this rental population – is unlikely to reverse this trend. Generation Rent is no longer simply a class in itself — it is becoming a class for itself, as well.

We appear, then, on the verge of a paradigm shift in housing policy. As the demographics of the housing market change, so must its politics. Wednesday’s budget signals that even the Conservatives – the “party of homeownership” – recognise the need for change. But it only goes halfway.

The gains for any political party willing to truly seize the day – to ditch the property-owning dream once and for all, to champion a property-renting one instead – are there for the taking. 

David Adler is a research association at the campaign group Generation Rent.

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