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.

 
 
 
 

Barnet council has decided a name for its new mainline station. Exciting!

Artist's impression of the new Brent Cross. Image: Hammerson.

I’ve ranted before about the horror of naming stations after the lines that they’re served by (screw you, City Thameslink). So, keeping things in perspective as ever, I’ve been quietly dreading the opening of the proposed new station in north London which has been going by the name of Brent Cross Thameslink.

I’ve been cheered, then, by the news that station wouldn’t be called that at all, but will instead go by the much better name Brent Cross West. It’s hardly the cancellation of Brexit, I’ll grant, but in 2017 I’ll take my relief wherever I can find it.

Some background on this. When the Brent Cross shopping centre opened besides the A406 North Circular Road in 1976, it was only the third large shopping mall to arrive in Britain, and the first in London. (The Elephant & Castle one was earlier, but smaller.) Four decades later, though, it’s decidedly titchy compared to newer, shinier malls such as those thrown up by Westfield – so for some years now, its owners, Hammerson, have wanted to extend the place.

That, through the vagaries of the planning process, got folded into a much bigger regeneration scheme, known as Brent Cross Cricklewood (because, basically, it extends that far). A new bigger shopping centre will be connected, via a green bridge over the A406, to another site to the south. There you’ll find a whole new town centre, 200 more shops, four parks, 4m square feet of offices space and 7,500 homes.

This is all obviously tremendously exciting, if you’re into shops and homes and offices and not into depressing, car-based industrial wastelands, which is what the area largely consists of at the moment.

The Brent Cross site. Image: Google.

One element of the new development is the new station, which’ll sit between Hendon and Cricklewood on the Thameslink route. New stations are almost as exciting as new shops/homes/offices, so on balance I'm pro.

What I’ve not been pro is the name. For a long time, the proposed station has been colloquially referred to as Brent Cross Thameslink, which annoys me for two reasons:

1) Route names make rubbish modifiers because what if the route name changes? And:

2) It’s confusing, because it’s nearly a mile from Brent Cross tube station. West Hampstead Thameslink (euch), by contrast, is right next to West Hampstead tube.

Various other names have been proposed for the station. In one newsletter, it was Brent Cross Parkway; on Wikipedia, it’s currently Brent Cross South, apparently through confusion about the name of the new town centre development.

This week, though, Barnet council quietly confirmed it’d be Brent Cross West:

Whilst the marketing and branding of BXS needs to be developed further, all parties agree that the station name should build upon the Brent Cross identity already established. Given the station is located to the west of Brent Cross, it is considered that the station should be named Brent Cross West. Network Rail have confirmed that this name is acceptable for operational purposes. Consequently, the Committee is asked to approve that the new station be named Brent Cross West.

Where the new station will appear on the map, marked by a silly red arrow. Image: TfL.

That will introduce another irritating anomaly to the map, giving the impression that the existing Brent Cross station is somehow more central than the new one, when in fact they’re either side of the development. And so:

Consideration has also been given as to whether to pursue a name change for the tube station from “Brent Cross” to “Brent Cross East”.

Which would sort of make sense, wouldn’t it? But alas:

However owing to the very high cost of changing maps and signage London-wide this is not currently being pursued.

This is probably for the best. Only a handful of tube stations have been renamed since 1950: the last was Shepherd’s Bush Market, which was until 2008 was simply Shepherd's Bush, despite being quite a long way from the Shepherd's Bush station on the Central line. That, to me, suggests that one of the two Bethnal Green stations might be a more plausible candidate for an early rename.


At any rate: it seems unlikely that TfL will be renaming its Brent Cross station to encourage more people to use the new national rail one any time soon. But at least it won’t be Brent Cross Thameslink.

Jonn Elledge is the editor of CityMetric. He is on Twitter as @jonnelledge and also has a Facebook page now for some reason. 

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