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.

 
 
 
 

Seven climate change myths put about by big oil companies

Oil is good for you! Image: Getty.

Since the start of this year, major players within the fossil fuel industry – “big oil” – have made some big announcements regarding climate change. BP revealed plans to reduce its greenhouse gas emissions by acquiring additional renewable energy companies. Royal Dutch Shell defended its $1-$2bn green energy annual budget. Even ExxonMobil, until recently relatively dismissive of the basic science behind climate change, included a section dedicated to reducing emissions in its yearly outlook for energy report.

But this idea of a “green” oil company producing “clean” fossil fuels is one that I would call a dangerous myth. Such myths obscure the irreconcilability between burning fossil fuels and environmental protection – yet they continue to be perpetuated to the detriment of our planet.

Myth 1: Climate change can be solved with the same thinking that created it

Measures put in place now to address climate change must be sustainable in the long run. A hasty, sticking plaster approach based on quick fixes and repurposed ideas will not suffice.

Yet this is precisely what some fossil fuel companies intend to do. To address climate change, major oil and gas companies are mostly doing what they have historically excelled at – more technology, more efficiency, and producing more fossil fuels.

But like the irresponsible gambler that cannot stop doubling down during a losing streak, the industry’s bet on more, more, more only means more ecological destruction. Irrespective of how efficient fossil fuel production becomes, that the industry’s core product can be 100 per cent environmentally sustainable is an illusion.

A potential glimmer of hope is carbon capture and storage (CCS), a process that sucks carbon out of the air and sends it back underground. But despite being praised by big oil as a silver bullet solution for climate change, CCS is yet another sticking plaster approach. Even CCS advocates suggest that it cannot currently be employed on a global, mass scale.

Myth 2: Climate change won’t spell the end of the fossil fuel industry

According to a recent report, climate change is one factor among several that has resulted in the end of big oil’s golden years – a time when oil was plenty, money quick, and the men at the top celebrated as cowboy capitalists.

Now, to ensure we do not surpass the dangerous 2°C threshold, we must realise that there is simply no place for “producers” of fossil fuels. After all, as scientists, financial experts, and activists have warned, if we want to avoid dangerous climate change, the proven reserves of the world’s biggest fossil fuel companies cannot be consumed.

Myth 3: Renewables investment means oil companies are seriously tackling climate change

Compared to overall capital expenditures, oil companies renewables’ investment is a miniscule drop in the barrel. Even then, as companies such as BP have demonstrated before, they will divest from renewables as soon as market conditions change.

Big oil companies’ green investments only produce tiny reductions in their overall greenhouse gas emissions. BP calls these effects “real sustainable reductions” – but they accounted for only 0.3 per cent of their total emissions reductions in 2016, 0.1 per cent in 2015, 0.1 per cent in 2014, and so on.


Myth 4: Hard climate regulation is not an option

One of the oil industry’s biggest fears regarding climate change is regulation. It is of such importance that BP recently hinted at big oil’s exodus from the EU if climate regulation took effect. Let’s be clear, we are talking about “command-and-control” regulation here, such as pollution limits, and not business-friendly tools such as carbon pricing or market-based quota systems.

There are many commercial reasons why the fossil fuel industry would prefer the latter over the former. Notably, regulation may result in a direct impact on the bottom line of fossil fuel companies given incurred costs. But climate regulation is – in combination with market-based mechanisms – required to address climate change. This is a widely accepted proposition advocated by mainstream economists, NGOs and most governments.

Myth 5: Without cheap fossil fuels, the developing world will stop

Total’s ex-CEO, the late Christoph de Margerie, once remarked: “Without access to energy, there is no development.” Although this is probably true, that this energy must come from fossil fuels is not. Consider, for example, how for 300 days last year Costa Rica relied entirely on renewable energy for its electricity needs. Even China, the world’s biggest polluter, is simultaneously the biggest investor in domestic renewables projects.

As the World Bank has highlighted, in contrast to big oil’s claims about producing more fossil fuels to end poverty, the sad truth is that by burning even the current fossil fuel stockpile, climate change will place millions of people back into poverty. The UN concurs, signalling that climate change will result in reduced crop yields, more waterborne diseases, higher food prices and greater civil unrest in developing parts of the world.

Myth 6: Big oil must be involved in climate policy-making

Fossil fuel companies insist that their involvement in climate policy-making is necessary, so much so that they have become part of the wallpaper at international environmental conferences. This neglects that fossil fuels are, in fact, a pretty large part of the problem. Big oil attends international environmental conferences for two reasons: lobbying and self-promotion.

Some UN organisations already recognise the risk of corporations hijacking the policy-making process. The World Health Organisation, for instance, forbids the tobacco industry from attending its conferences. The UN’s climate change arm, the UNFCCC, should take note.

Myth 7: Nature can and must be “tamed” to address climate change

If you mess with mother nature, she bites back. As scientists reiterate, natural systems are complex, unpredictable, and even hostile when disrupted.

Climate change is a prime example. Small changes in the chemical makeup of the atmosphere may have drastic implications for Earth’s inhabitants.

The ConversationFossil fuel companies reject that natural systems are fragile – as evidenced by their expansive operations in ecologically vulnerable areas such as the Arctic. The “wild” aspect of nature is considered something to be controlled and dominated. This myth merely serves as a way to boost egos. As independent scientist James Lovelock wrote, “The idea that humans are yet intelligent enough to serve as stewards of the Earth is among the most hubristic ever.”

George Ferns, Lecturer in Management, Employment and Organisation, Cardiff University.

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