Tag Archives: traffic

‘No significant difference’ in air pollution exposure between rush-hour commuters and others

People who commute during rush hour are obviously exposed to more traffic-related air pollution than those who do not. However, a new study comes to show that the difference is not very meaningful, or statistically significant.

Image via Pixabay.

Air pollution is bad for you, we all know that. But we all need to make rent, so we brave the streets to get to work on time, often through engine exhaust, dust, and other pollutants. In order to gauge just how much more significant this exposure is during rush hour compared to other times of day, researchers at the George Mason University College (GMU) College of Health and Human Services monitored commuters during their trips using personal air pollution monitors.

Although rush-hour commuters are definitely exposed to more air pollution from traffic than their peers, they explain, the difference is not that large.

Just as bad

“This is one of the first studies to utilize in-vehicle monitoring, specifically on-board diagnostics data loggers, to understand real-world commuting behaviors for environmental health,” said Dr. Jenna Krall, assistant professor at the GMU and lead author of the study. “Linking these data with personal air pollution monitoring allowed us to better understand how commuter characteristics are associated with sources of air pollution exposures.”

The team wanted to understand how factors such as departure time, frequency, and commute length influence our exposure to air pollution. For the study, they employed personal air pollution monitors to see how much air pollution different participants were actually exposed to over their commute, then mixing this in with the time and route they took. They were particularly interested in exposure to fine particulate matter (PM2.5), which in this context mainly come from traffic-related sources including exhaust, brake wear, and salts used to de-ice roads.

All in all, the study included 46 women in northern Virginia who commuted using their personal vehicles and were monitored over a 48-hour period. The authors found that differences between those commuting during rush hour and the rest were not statistically significant.

Still, the findings are especially useful in the context we find ourselves in right now. The coronavirus generally attacks our respiratory system, which is most exposed to air pollution. We’re also seeing a gradual easing away of measures implemented during the pandemic, and more people are getting called back to the office from home. Understanding the effect of air pollution and patterns of exposure to it could go a long way towards preserving public health.

That being said, the findings still lack a proper background into which they can integrate. Commuters form incredibly complex systems, and there’s still a lot of unknowns regarding this behavior.

“The current research cannot tell us whether modifying commutes, for example by avoiding highways or commuting outside of rush hour, will lower traffic pollution exposures for commuters. More research is needed to determine what changes would be effective to lower exposures,” says Krall.

The paper “Commuter types identified using clustering and their associations with source-specific PM2.5” has been published in the journal Environmental Research.

Cities need to wean off of cars in the future or become endless traffic jams

If we want cities to remain viable in the future, we’ll have to rethink transportation and car use, a new paper warns.

Image via Pixabay.

Researchers at the University College London (UCL) trying to understand the city of the future say it doesn’t mix well with automobiles. If current trends continue, they explain, cities will eventually be swamped by cars. This will drain ever-more resources on infrastructure, and waste ever-more of our time through busy, slow commutes.

Cars will still be used, undoubtedly, but the authors recommend that walking or cycling should be promoted instead of these for short, local trips. Public transport networks should be improved and encouraged for longer journeys, where possible. In order to keep cities livable in the future, the team concludes, cars should only be used for special occasions or emergencies.

Too many

“The city of the future, with millions of people, cannot be constructed around cars and their expensive infrastructure,” explains lead author Dr. Rafael Prieto Curiel. In a few decades, we will have cities with 40 or 50 million inhabitants, and these could resemble car parks with 40 or 50 million cars.”

“The idea that we need cars comes from a very polluting industry and very expensive marketing.”

The results are based on a mathematical framework that models the use of cars in a city. For the purposes of this study, the model assumed that citizens would either use a car on a daily basis or used public transport. What the model tracked was how long (in terms of time) each journey would take, as time was considered to be the main cost individuals consider when deciding on how to travel. The baseline for the model was a city in which there is no personal car traffic, just cycling, walking, and public transport.

On the other extreme, the model considered a city with 50 million inhabitants and 50 million cars, where all residents would commute to work with their own vehicle in order to save up on time. This virtual city, quite understandably, saw much higher levels of congestion and required more spending on infrastructure such as avenues, bridges, and car parks in order to accommodate all that traffic.

Surprisingly however, while the people in this city opted to drive to work to get there sooner, they actually lost more time than those in other scenarios. While driving is the fastest solution for individuals, when everybody opted for it, commuting times were the longest seen in any of the simulated cities. The team explains that this comes down to traffic — all those cars on the road create jams and slow everybody down significantly.

Where to go from here — and how?

The paper offers reliable evidence that better public transport infrastructure would improve the travel time for citizens, as more of them would opt for public transport over personal vehicles. It also shows that even without any improvements in public transport, time costs for commuters and citizens travelling through the city can be reduced by lowering the number of people driving at any single time.

While they don’t advocate for this solution, the authors give a scenario where a group of people is allowed to drive one week, but must use other transportation options the next one, such as ride-sharing or public transport. Average commuting times could be reduced by up to 25% (depending on the size of the group) for all citizens due to reduced car traffic, less congestion, and faster transportation throughout the city on average.

However, the authors underline that decreasing car use in cities hinges on giving people efficient travel alternatives, as well as local shops and services (so as to reduce demand for transport in the first place). Interventions such as congestion charges, tolls, and driving and parking controls can help discourage car use, but unless people have alternatives to pick from, and are informed as to the local costs of car use, we can’t reasonably expect them to give up the use of their cars. Some cities have tried simply banning some vehicles based on their license plate, such as Mexico City, but this backfired as residents purchased older, cheaper, and more polluting cars to get around the ban.

Not making any changes isn’t a viable option, either. They note that car production is fast increasing, and has actually outstripped population growth. In 2019, 80 million cars were produced, while the population increased by 78 million worldwide. Pollution is a big concern: globally, car manufacturing (including electric vehicles) contributes 4% of total carbon dioxide emissions. Energy use, be it petrol, diesel, or electricity, also generates pollution (right under our noses, in the case of combustion engines) and added costs. Material costs related to the construction and maintenance of infrastructure required by these cars, as well as time lost in traffic due to congestion, are also added costs most people don’t consider.

“Currently, much of the land in cities is dedicated to cars. If our goal is to have more liveable and sustainable cities, then we must take part of this land and allocate it to alternative modes of transportation: walking, cycling, and public transport,” says co-author Dr. Humberto González Ramírez from the Université Gustave Eiffel.

Such research is actually very important, as sustainable transportation is a key objective for many large cities as part of one of the UN’s Sustainable Development Goals. This model, the authors explain, can easily be adapted to other cities around the world, although it is particularly useful for locales where the majority of travel (>90%) is done by car, which is most common for cities in the US.

The paper “A paradox of traffic and extra cars in a city as a collective behaviour” has been published in the journal Royal Society Open Science.

Is it time to prohibit left turns in busy intersections? This transportation engineer thinks so

Credit: Pexels.

Whenever drivers make a left-hand turn in a busy intersection, they have to cross oncoming traffic. This creates temporary bottlenecks that slow down traffic — in some situations, even to a grinding halt. Left-hand turns can also be dangerous, being involved in nearly 60% of all crashes occurring at intersections and causing three times more pedestrian fatalities than right-hand turns. For these reasons, and more, some experts believe it is time to remove left-hand turns from our intersections, with research to back it up.

For more than a decade, Vikash Gayah, an Associate Professor of Civil Engineering at Penn State University, has been performing mathematical models and traffic simulations analyzing the impact of left turns. His research shows that — at least for grid-like street networks found in many U.S. cities — eliminating left-hand turns may greatly improve traffic overall.

Removing left turns could save fuel, time, and even human lives

According to Gayah, the main weakness of a two-way network with prohibited left turns is that it can lead to longer travel times when these networks are congested. Rather than making a quick left turn, some drivers would have to make three right turns to get in the right direction. However, Gayah’s research shows that, on average, drivers would only have to drive an additional block in prohibited left turn scenarios, but these delays would be more than offset by the smoother traffic.

These simulations are backed up by some real-life data, most notably from UPS. Think about it, when was the last time you saw a UPS truck make a left-hand turn? The reason why you can’t recall is that the company changed its delivery routes way back in 2004 in order to minimize the number of left-hand turns its drivers make. Carriers make left-hand turns only when the action is unavoidable.

Considering UPS’s massive fleet, this seemingly slight adjustment adds up to make a massive difference. Since it eliminated left-hand turns from its routes, UPS claims that every year it saves 10 million gallons of fuel, cuts 20,000 tons of carbon emissions, and delivers 350,000 extra packages since drivers spend less time stuck in intersections. Since vehicles are now equipped with GPS devices, onboard computers, and smartphones, avoiding left-hand turns has never been easier.

UPS isn’t alone. In the Commercial Driver’s License (CDL) manual, the authors address the following warning to truckers in Section 2 concerning left-hand turns:: “Before you start across a road, make sure you can get all the way across before traffic reaches you.”

But getting rid of left turns across an entire city sounds like an administrative nightmare and rather unrealistic. A more practical approach would be to identify and then remove left turns in individual locations where some form of intervention is most needed.

In a recently published study in March 2021 in the journal Transportation Research Record, Gayah and colleagues devised a computer algorithm that can evaluate which intersections should prohibit left turns to improve traffic.

The algorithm can be fed data from traffic simulations to pinpoint which intersections need to remove the left turns. Each city is different, but Gayah says that one general pattern is that left-turn restrictions are most effective at busier intersections in the centers of cities than at less busy intersections farther from the center.

“This is because the busier the intersection, the more people will benefit from smoother traffic flow. These central intersections also tend to have alternative routes available that minimize any additional distance traveled due to the restrictions. Lastly, fewer cars tend to turn left at these central intersections to begin with so the negative impact of removing left turns is relatively small,” Gayah wrote in an explanatory article about his research for The Conversation.

These are all solid arguments in favor of changing legislation regarding left-hand turns. In some situations, left-hand turns smoothen traffic and should be kept in place. However, there is ample evidence in favor of scrapping them from most busy intersections in large cities. In the meantime, consider these tips when making a left-hand turn:

  • Always use a turn signal;
  • Only make the turn if you can safely complete it;
  • Check your blind spots;
  • Know what is in front of and behind you;
  • Yield to pedestrians and vehicles who have the right-of-way;
  • Don’t stop suddenly without warning;
  • Avoid cutting corners;

AI traffic management could finally declog urban roads

Credit: Flickr, Marianna.

Year-by-year, traffic has only gotten worse in most cities across the world. This is particularly true for cities in Asia where the number of traffic congestions has grown exponentially due to rapid urbanization and increased median income. In the Indian capital of Delhi, for instance, drivers spend as much as 58% more time stuck in traffic compared to drivers in any other city in the world. In the face of this mounting economic, health, and environmental challenge, technology may be one of our best allies when it comes to reducing time spent in traffic.

Expanding roadways, improving public transit, and encouraging alternative forms of mobility are definitely important and have their part to play in improving traffic. However, out of all possible solutions, intelligent traffic management systems driven by artificial intelligence (AI) may have the best return on investment — by far.

Such systems employ machine learning, computer vision, and other AI technologies to make sense of large swaths of data collected by sensors and cameras that record road activity, even if markings haven’t been recently repainted by line marking machines and are poorly visible. The systems can then provide insights that local operators can use to make real-time decisions to optimize traffic, such as changing the timing of red lights.

Chinese tech giant Alibaba has already implemented a traffic management AI called City Brain in 23 cities across the country, as well as in other countries such as Malaysia. The platform crunches data in real-time from video cameras in intersections and GPS data from local cars and buses to coordinate more than 1,000 road signals around a city.

After implementing Alibaba’s solution, Hangzhou, a city of 7 million, dropped from China’s fifth most congested cities to 57th on the list. As a result, commutes have shortened drastically. Also, first responders such as fire trucks and ambulances have halved the amount of time it took to respond to emergencies.

“The cities in China are probably facing more challenges than any other city,” Wang Jian, chairman of Alibaba’s technology steering committee, told Techwire Asia.

Elsewhere, at Yanbu Industrial City, a major industrial hub in Saudi Arabia, Huawei has implemented an AI-driven traffic solution that comprises over 250 HD cameras operating at 16 major road intersections. The system supplies high-quality images and videos that feed real-time data to local officials that they can use to immediately take action or plan a long-term strategy.

Huawei’s solution, called Intelligent Traffic Management System (ITMS), runs smart algorithms that identify traffic violations in real-time, including red lights, crossing lanes, reverse driving, and lane marking infractions. Although the system runs about 100,000 data records, it is able to respond within seconds.

In the United States, the city of Pittsburgh has deployed the Surtrac intelligent traffic signal control system at 50 intersections that not only reduced travel times by 26% and wait times at intersections by 41% but also curbed transport emissions by 21%.

The next step is to have traffic signals talk to cars. Engineers in Pittsburgh have already installed short-range radios at 24 intersections. Such systems could then let drivers know of upcoming traffic conditions or inform them that lights are about to change, increasing safety and relieving congestion. Traffic engineers nationwide have not had a tool to give them anywhere near real-time estimation of transportation network states — but that has now changed.

We could be heading towards a transportation breakthrough. AI is poised to revamp urban transportation, relieving bottlenecks and chokepoints that routinely snarl our urban traffic. This could not only reduce congestion and reduce travel time but also reduce emissions (by reducing the time spent in traffic). It won’t happen overnight, but it could happen soon.

One species of the cotoneaster plant could help absorb traffic pollution

New work at the Royal Horticultural Society and the University of Reading, both in the UK, found that a hedge plant common to southwestern China can help keep the air clean of car exhaust.

Image credits Henryk Niestrój.

The plant is known as Franchet’s or orange cotoneaster (Cotoneaster franchetii), and is particularly effective at filtering our air pollutants associated with automobile exhaust. The findings come as part of an ongoing, 10-year research effort that aims to understand which plants could do the most good in urban settings against pollution.

A good plan(t)

The team has been hard at work testing the many species of bush, shrub, and tree that make common appearances in urban areas across the world. During that time, they haven’t shied away from looking even at the more modest plants. This helped them show that some of the most effective plants at protecting against air pollution, as well as the traits that make them so.

As far as hedges are concerned, a dense canopy and rough, hairy leaves make for the best pollution scrubber. The cotoneaster definitely fits this description, the team explains, so they tested it.

All in all, Franchet’s cotoneaster was roughly 20% more effective at cleaning the air of pollutants around busy street sections than any other hedge in the study. The authors note that they didn’t see any particular difference between it and other hedge species on streets with low traffic, however. This latter finding suggests that different plant species could be more useful in different areas, we just need to learn to play to their strengths, so to speak. City planners as well as residents can benefit from such knowledge.

Franchet’s cotoneaster itself would be ideal for homeowners whose property abuts busy streets. The plant would also be a good choice for city planners to line such avenues with. In both cases, it will help lower the amount of pollutants individuals will be exposed to in such areas.

Today, Franchet’s cotoneaster isn’t very common in areas outside its natural habitat, but it’s not absent, either. Several cultivars of this plant were taken overseas for private collections or their aesthetic value. As an invasive plant species, it’s most common in the wild around areas of habitation from where it escaped. It usually grows under 3 meters tall with relatively small, oval leaves with a shiny green top and white-felted underside. It flowers in June with pink or white petals which give way to red-orange berries. However, since there are many cultivars of this species, it is quite hard to give more details for identifying it.

The paper “Evaluating the Effectiveness of Urban Hedges as Air Pollution Barriers: Importance of Sampling Method, Species Characteristics and Site Location” has been published in the journal Environments.

Exposure to traffic noise promotes obesity

Living in areas with high traffic has several adverse health effects, mostly due to the air pollution generated by vehicles. But even the noise itself is pretty bad for your health, a new study reports.

image via Pixabay.

New research at the University of Oxford and the University of Leicester found that long-term exposure to traffic noise could be a promoter for obesity. People living in such areas had a higher chance of having an increased body mass index and waist circumference, the study explains. This effect was more pronounced in areas with louder traffic noise.

Heavy traffic

“While modest, the data revealed an association between those living in high traffic-noise areas and obesity, at around a 2% increase in obesity prevalence for every 10dB of added noise,” says lead author Dr. Samuel Yutong Cai, a senior epidemiologist at the University of Oxford.

“The association persisted even when we accounted for a wide range of lifestyle factors, such as smoking, alcohol use, physical activity, and diet, as well as when taking into account the socio-economic status of both individuals and the overall area. Air pollution was also accounted for, especially those related to traffic.”

The study worked with data from more than 500,000 people, data which it mined from three European biobanks in the UK, the Netherlands, and Norway.

The authors describe the identified link as ‘modest’ because they uncovered an interplay between traffic noise and indicators of obesity in individuals from the UK and Norway, but not in the Netherlands. By themselves, these results aren’t enough to reliably confirm a cause and effect relationship between the two. However, the authors note that the findings are backed up by previous similar findings in other countries in Europe.

Still, the findings can’t, as of right now, be used as proof that one causes the other. They do, however, offer enough evidence to warrant further research into the topic.

Over 100 million people in the EU live in areas where road traffic noises exceeds 55dB (decibels) in volume, which is the safety threshold set by the EU, the paper notes. This exposure could be a driver of obesity.

“It is well-known that unwanted noise can affect quality of life and disturb sleep,” says co-author Professor Anna Hansell, Director of the University of Leicester’s Centre for Environmental Health and Sustainability.

“Recent studies have raised concerns that it also may influence general health, with some studies suggesting links to heart attacks and diabetes. Road traffic noise may increase stress levels, which can result in putting on weight, especially around the waist.”

Most of our efforts to stay healthy and avoid the extra pounds only work on an individual level — think things like exercise or dieting. And we should definitely keep doing that, as they are still the most effective tools we have against obesity. But policies that reduce traffic noise (or at least, exposure to it) may help further tackle this issue “on a population level,” argues Dr Cai.

“As we emerge and recover from COVID-19, we would encourage the government to look at policies that could manage traffic better and make our public spaces safer, cleaner and quieter,” he adds.

“Air pollution is already a well-known health risk, but we now have increasing evidence that traffic noise is an equally important public health problem. The UK should take this opportunity to think about how we can, as a society, re-organize cities and communities to support our health and reap better health outcomes across the whole population.”

The team is now testing how exposure to other sources of noise, such as that produced by aircraft, influences weight gain.

The paper “Impact of road traffic noise on obesity measures: observational study of three European cohorts” has been published in the journal Environmental Research.

A steep traffic toll in NYC would reduce traffic and pollution, study finds

Enforcing a $20 toll for cars and taxis to enter the central business district of Manhattan would reduce traffic congestion by up to 40% and greenhouse gas emissions by 15%, while also increasing the use of public transit by 6%, according to new research.

Credit Flickr

New York City is among the most congested traffic spots in the world, with a daytime population of almost four million people. Overcrowded facilities, undesirable travel times, excessive fuel consumption, and air pollution are among many other undesirable experiences faced by its residents every day.

Governor Andrew Cuomo urged the Legislature to pass congestion traffic pricing to cull vehicles from Manhattan and to help fund more than $1 billion in public transit and subway repairs. Tolls were slated to begin next year, but delays due to the COVID-19 pandemic, as well as in federal approval means the idea will likely be pushed back.

“If we charge a high dollar amount of tolls, we can decrease the number of cars and taxis, shrink gridlock, bring down carbon dioxide emissions and reduce particulate matter,” Oliver Gao, director of Cornell’s Center for Transportation, Environment and Community Health, said in a statement. “This is good news for the environment and from a public health perspective.”

The benefits of a toll

The study by Cornell University and the City College of New York studied how pricing scenarios in New York City can impact transportation demand, network performance, and traffic emissions. The core of the analysis is based on analyzing changes in the chain of daily activities of individuals in response to increases in the charging fees.

About one million tons of greenhouse gas emissions – mostly carbon dioxide – come from automobile and truck traffic in lower Manhattan annually. Modeling different scenarios using air quality processing software, the researchers determined exhaust emission reductions based on the charged tolls.

They found that a $5 toll would result in a reduction of 72,648 tons of greenhouse gas emissions annually. A $10 toll would lead to a reduction of 119,097 tons, and a $15 toll would yield a 157,747-ton drop. A $20 toll would be the ideal scenario, reducing greenhouse gas emissions by 182,065 tons per year.

Implementing entrance tolls would also drop the volume of particulate – dust and other tiny particles measuring less than 2.5 micrometers that are linked to poor health and give Manhattan a hanging fog. At the same time, traffic delays would be reduced between 15% and 32%, depending on the pricing scenario.

“All of us know that policymakers don’t like to charge people for driving into the city. Policymakers try to avoid it. But if we want to avoid climate change impact, these are the kind of policies that need to be considered and implemented,” Cornell postdoctoral researcher Mohammad Tayarani said in a statement.

The study was published in the journal Sustainability.

San Francisco's Golden Gate Bridge. Credit: Pixabay.

Uber and Lyft may have actually made traffic worse in San Francisco

San Francisco's Golden Gate Bridge. Credit: Pixabay.

San Francisco’s Golden Gate Bridge. Credit: Pixabay.

Because they have the potential to reduce our reliance on private cars, ride-sharing apps such as Uber or Lyft intuitively sound like they could solve traffic congestion problems by removing vehicles from the road. But, in reality, things aren’t that simple. According to a new study, ride-sharing might actually make traffic worse in some cities. In San Francisco, for instance, researchers found that these services increased delays by 62% between 2010 and 2016 compared to 22% in a counterfactual 2016 scenario without such services.

Transportation network companies (TNCs) are on-demand ride services where rides are arranged through a mobile app to connect the passenger with the driver of a personal vehicle. In the future, many believe that TNCs will evolve into fleets of self-driving cars that will ferry passengers around the clock.

TNCs have massively grown in their use, accounting for 15% of all intra-San Francisco vehicle trips in 2016 — that’s 12 times the number of taxi trips. Elsewhere, in New York City, TNC ridership equaled that of yellow cabs and doubled annually between 2014 and 2016.

Ride-sharing is often hailed as a solution to traffic congestion problems that plague virtually all major cities around the globe. TNCs may reduce road traffic by shifting trips from personal vehicle to public transit by providing better connections to regional public transportation. Ride-sharing is also a convenient alternative to owning a car, motivating individuals to shift other trips to transit or non-motorized modes (walking, bike, etc.).

However, there are other mechanisms by which ride-sharing might increase traffic congestion. The most obvious contributor is deadheading or the out-of-service period a vehicle has to spend with no passenger. Studies estimate that deadheading is responsible for 50% of TNC traveled miles in New York and 20% in San Francisco. It is also reasonable to believe that many people who would have used public transportation, walked, traveled by bike, or would have made no movement at all are now contributing to traffic congestion by using TNCs because it is so convenient. Finally, TNCs contribute to congestion during the frequent pickups and drop-offs that they have to make — for instance, this behavior causes similar effects to those seen in areas that traditionally rely heavily on taxis.

Researchers at the University of Kentucky and the San Francisco County Transportation Authority wanted to address this debate by comparing traffic congestion in San Francisco with and without the presence of ride-sharing apps in the city. To this aim, they scraped data from the application programming interfaces of Uber and Lyft, along with observational travel times. This allowed the authors to gauge the effect of TNCs on San Francisco’s traffic between 2010 conditions when TNC activity is negligible and 2016 conditions when it is not.

Daily TNC pickups and drop-offs for an average Wednesday in fall 2016 ( Darker colors represent a higher density of TNC activity). Credit: Science Advances.

Daily TNC pickups and drop-offs for an average Wednesday in fall 2016 (
Darker colors represent a higher density of TNC activity). Credit: Science Advances.

In order to exclude other non-TNC factors that contribute to traffic congestion, the authors turned to San Francisco’s travel demand model (SF-CHAMP), which produces estimates of traffic volumes on all roads in San Francisco and is sensitive to changes in population and demographics, employment, transportation networks, and congestion. The version of the model used in this study was calibrated for 2010 conditions, providing a counterfactual case where ride-sharing doesn’t exist.

The results suggest that Uber and Lyft are helping drive more traffic congestion rather than unclogging it. The researchers found that ride-sharing services made delays 62% worse, compared to a 22% increase in travel delays in the scenario where there are no TNCs. The average speed of on-road vehicles decreased by 13% due to TNCs but only 4% in the counterfactual model. Finally, commuters now have to use a longer buffer time to make sure they arrive at their destination on time because travel duration is less reliable overall. According to the findings, this buffer is now 15% higher compared to the natural 6% increase where Uber and Lyft don’t exist.

“The results show some substitution between TNCs and other car trips, but that most TNC trips are adding new cars to the road. The estimated models show that TNC vehicles stopping at the curb to pick up or drop off passengers have a notable disruptive effect on traffic flow, especially on major arterials,” the authors wrote in Science Advances

The authors say that their findings should be of interest to policy makers and transportation planners who are interested in regulating TNCs in the best interest of the general public of San Francisco. Some solutions include allocating curb spaces and right-of-ways for ride-sharing vehicles and integrating new mobility services.


Traffic sign.

Cannabis legalization increases traffic fatalities — but mostly in neighboring, un-legalized states

New research from the Monash University looks at the effect cannabis legalization has on traffic fatalities.

Traffic sign.

Image via Pixabay.

Three US states have legalized recreational cannabis sales (RCS) so far: Colorado and Washington in 2015, followed by Oregon in 2015. But does the ol’ herb impact traffic fatalities? New research from the Monash University says yes — especially in areas bordering these states.

Cannabis tourism

“The effect of cannabis legalisation on traffic fatalities is a growing public health concern,” says Dr. Tyler Lane, lead author of the study.

“The results suggest that legalising the sale of cannabis for recreational use can lead to a temporary increase in traffic fatalities in legalising states. This spills over into neighbouring jurisdictions through cross-border sales, trafficking, or cannabis tourists driving back to their state of residence while impaired.”

The team calculated a baseline number of deaths resulted from traffic accidents in the three states and nine neighboring jurisdictions — Kansas, Nebraska, New Mexico, Oklahoma, Utah, British Columbia, Oregon, California, and Nevada — prior to legalization.

They compared this with figures of traffic fatalities recorded after legalization to get the number of additional deaths per month compared to states that had not changed cannabis laws. Traffic fatalities increased only temporarily, they report — this increase lasted for about one year following legalization. The study area sums up a population of roughly 27 million people, and saw an additional 170 deaths in the first six months following legalization, the team reports.

However, the team was also surprised to find that neighboring states and provinces saw a slightly larger increase in fatalities than the studied areas. This effect was more pronounced in population centers closest to the border of a legalizing state. The team believes this comes down to cannabis users driving interstate to make purchases before returning under the influence.

This ‘cannabis tourism’ has important implications for both legalizing states and their neighbors, the team explains. Furthermore, the results may be applicable elsewhere, too, as prohibitions against cannabis are lifted.

“Our findings suggest that policymakers should consult with neighbouring jurisdictions when liberalising cannabis policy to mitigate any deleterious effects,” says Dr. Lane.

She adds that these results stand in contrast to research on medicinal cannabis, which suggests it decreases traffic fatalities. One reason for the difference may be that medicinal users tend to substitute cannabis for other substances, including alcohol, which have a greater effect on impairment. Recreational users are less likely to substitute and more likely to combine alcohol and cannabis, which has a much bigger effect than either in isolation.

The paper “Traffic fatalities within US states that have legalized recreational cannabis sales and their neighbours” has been published in the journal Addiction.

Credit: Pixabay.

Watch out! More pedestrians are killed by cars on Halloween than any other regular evening

Credit: Pixabay.

Credit: Pixabay.

In the evening of October’s last day, millions of American kids walk door to door in their neighborhoods to collect candy — and they’re not alone. Teens and adults alike dress up and hit the streets too, each with their own version of ‘trick or treat’. But while Halloween is a great opportunity to have fun and form stronger bonds with your community, it can also be a dangerous time of the year. A new study analyzed four decades worth of fatal traffic crashes and found more people are killed by cars on Halloween than any other regular evening.

Researchers at the University of British Columbia, Canada, combed through data from the National Highway Traffic Safety Administration’s Fatality Analysis Reporting System. Over a 42-year study interval, 1,580,608 fatal traffic crashes were recorded, involving 2,333,302 drivers and 268,468 pedestrians.

A total of 608 pedestrian fatalities occurred on the 42 Halloween evenings, whereas 851 pedestrian fatalities occurred on the 84 control evenings, the researchers reported in the journal JAMA PediatricsThis means that “the relative risk of a pedestrian fatality was 43% higher on Halloween compared with control evening.” The most vulnerable group were children aged 4 to 8, who had a tenfold risk of fatality from a car crash.

“Halloween traffic fatalities are a tragic annual reminder of routine gaps in traffic safety. On Halloween and throughout the year, most childhood pedestrian deaths occur within residential neighborhoods. Such events highlight deficiencies of the built environment (eg, lack of sidewalks, unsafe street crossings), shortcomings in public policy (eg, insufficient space for play), and failures in traffic control (eg, excessive speed),” the authors noted in their study.

So what should we do? The authors call for measures such as traffic calming and automated speed enforcement in residential neighborhoods in order to make streets safer for kids to cross. Other important measures that might prevent child pedestrian fatalities include improving pedestrian visibility by limiting on-street parking and incorporating reflective patches onto clothing.

The researchers argue that this isn’t about one night anymore. All of these measures will help curb pedestrian fatalities year-round.

“Halloween trick-or-treating encourages creativity, physical activity, and neighborhood engagement. Trick-or-treating should not be abolished in a misguided effort to eliminate Halloween-associated risk. Instead, policymakers, physicians, and parents should act to make residential streets safer for pedestrians on Halloween and throughout the year,” the researchers concluded.

Loud noises are bad for your heart — and your cells

Loud noises are more than just annoying — they can affect you at a cellular level, a new study has revealed.

Image in public domain.

Much like air pollution, noise pollution also increases the risk of disease, but there’s still a lot of controversy around how it does so.

Plenty of anecdotal and empirical evidence has linked environmental noises to a series of health issues. More than simply disrupting our sleep and moments of relaxation, constant noises also seem to take a significant toll on our body.

Traffic noise, for instance, has been linked to an increase in the risk of heart disease, but no mechanism has been discovered that explains this increased incidence. Now, in a new review, scientists describe how that happens.

Thomas Munzel, lead author of the study, believes there is now plenty of evidence that noise makes you sick. After carrying out a review of previous studies, he and his team concluded that noise induces a stress response through the sympathetic nervous system — the system which activates the so-called fight or flight response. In turn, this increases hormone levels, which ultimately leads to vascular damage and several other metabolic abnormalities.

If this is the case, then it supports the idea that transportation noise contributes to the development of heart disease risk factors such as hypertension and diabetes. This was previously suggested in both animal and human studies.

However, this is still an open debate, as the effect of noise pollution is extremely difficult from other influences. For instance, people living next to noisy roads are also more exposed to noise pollution, but houses near such roads also tend to be cheaper, which means that, on average, the occupants of the houses have lower incomes and therefore might not be able to afford healthier foods. It’s a complex issue, but at least for now, increasing evidence seems to indicate that noise is indeed a cause of health concern.

The World Health Organization calls noise pollution “an underestimated threat” that can cause “sleep disturbance, cardiovascular effects, poorer work and school performance, hearing impairment.” The agency recommends less than 30 A-weighted decibels in the bedroom for a good night’s sleep.

Researchers also suggest that this is something policymakers should work towards fixing, as more and more of the population is exposed to transportation noise.

“As the percentage of the population exposed to detrimental levels of transportation noise are rising, new developments and legislation to reduce noise are important for public health,” Münzel concludes.

Journal Reference: Thomas Münzel, Frank P. Schmidt, Sebastian Steven, Johannes Herzog, Andreas Daiber and Mette Sørensen. Environmental Noise and the Cardiovascular System. DOI: 10.1016/j.jacc.2017.12.015

These are the cities with the worst traffic (continent by continent)

Traffic is a growing problem in many parts of the world, but if you’re going to these cities — pack some extra patience.

In 2004, a company TomTom launched the first personal navigation device, and the world would never be the same. Since then, they’ve sold tens of millions of such devices around the world, and as a result, have access to a trove of data about the world’s traffic. They’ve charted the world’s cities based on how bad the traffic is, based on a congestion score which shows how much extra time you need to navigate that city. A 33% score means you need 33% more time.

We’ll only consider large cities here (over 800,000 people), though TomTom also has ratings for some smaller cities. Let’s have a look at the worst cities overall, and then we can break it down continent by continent.

Worst traffic in the world

  • 10. Beijing (China) — 46%

China’s bustling capital “only” comes in at number ten, despite being the world’s second most populous city proper. Thanks to its national highways, expressways, and high-speed rail network, things aren’t worse, but even these thick veins can’t keep up with the over 21 million people who call Beijing home.

  • 9. Tainan (Taiwan) — 46%

The congestion of this Taiwan municipality grew by a whopping 10% since last year, in part due to tourism.

  • 8. Rio de Janeiro (Brazil) — 47%

Despite remaining stable since last year, Rio’s streets are still a nightmare to drive on. Rio is surrounded by mountains, and that makes traffic management even more difficult.

  • 7. Chengdu (China) — 47%

Unsurprisingly, China’s sparkling metropoles often have massive traffic problems, largely due to the fact that they weren’t designed to fit so many people.

Despite many people cycling, China’s growing cities still have a massive traffic problem. Traffic jam in Chengdu, image in Public Domain.

  • 6. Istanbul (Turkey) — 49%

Despite a slight improvement from last year, the roads of Istanbul are still a chaotic drag to navigate. Traffic jams are a common sighting, as are drivers trying to improvise their way out of a jam and making it much worse.

  • 5. Bucharest (Romania) — 50%

Perhaps surprisingly, the Romanian capital of Bucharest is Europe’s most congested city. Improper city planning and an overall disregard of such problems have made driving in Bucharest worse and worse, after year.

Bucharest does have its traffic, but it’s certainly not on the road. Image credits: Babu / Wikipedia.

  • 4. Chongqing (China) — 52%

The most congested city in China (though not in Asia) is Chongqing, a municipality which was created only in 1997, but now has a population of over 18 million.

  • 3. Jakarta (Indonesia) — 58%

Everyone who’s ever been in Jakarta will tell you its streets are a nightmare. Jakarta’s business opportunities, as well as its potential to offer a higher standard of living, attract people from all over Indonesia, but that’s taking a toll on the streets.

  • 2. Bangkok (Thailand) — 61%

Asia’s most congested city is Bangkok. The city hosts 12.6 percent of the country’s population, dwarfing all other urban centers in Thailand, but also having the obvious downside of bad traffic.

The traffic in Bangkok — sometimes you move, and sometimes… you just don’t. Image credits: Mark Fischer / Flickr.

  • 1. Mexico City (Mexico) — 66%

According to TomTom, the world’s most congested city is by far Mexico City. From morning to evening, the city’s streets are clumped with cars that seem to be going nowhere — and often, they really are going nowhere.

Worst traffic in North America

Congestion is getting worse and worse in America. The average US commuter spends 42 hours stuck in traffic a year, according to a report by the Texas Transportation Institute.

The United States takes seven spots, Canada takes two, but Mexico tops the charts.

  • 10. Portland (US) — 29%
  • 9. Miami (US) — 30%

Rush hour in Miami is absolutely awful. Image credits: B137 / Wikipedia.

  • 8. Toronto (Canada) — 30%
  • 7. San José (US) — 32%
  • 6. Seattle (US) — 34%
  • 5. New York (US) — 35%

Few things are as recognizable as a New York traffic jam, and according to this data, there’s lots of them. Image credits: joiseyshowaa.

  • 4. Vancouver (Canada) — 39% 
  • 3. San Francisco (US) — 39%
  • 2. Los Angeles (US) — 45%
  • 1. Mexico City (Mexico) — 66%. Worst traffic in the world.

This photo by Dennis Mojado sums up the traffic in Mexico City quite nicely.

Along with the mayors of Paris, Athens, and Madrid, Mexico City has vowed to ban all diesels from the city by 2025.

Worst traffic in Europe

The United States takes seven spots, Canada takes two, but Mexico tops the charts.

  • 10. Athens (Greece) — 37%

As the economy finally starts to improve in the Greek capital, the traffic also starts to become rougher and rougher.

  • 9. Manchester (UK) — 38%

Manchester has remained more or less constant in recent years. It’s bad, but at least it’s not getting much worse.

  • 8. Brussels (Belgium) — 38%
  • 7. Paris (France) — 38%

The city of lights, indeed. Due to intense traffic, Paris is also battling pollution and smog. Image credits: Nelson Minar / Flickr.

  • 6. Rome (Italy) — 40%

Rome’s traffic issues are well known, and caused in part by the municipality’s inability to build new roads and subways due to the archaeological ruins. The loads of tourists coming every year to Italy’s capital certainly don’t help.

  • 5. Marseille (France) — 40%
  • 4. London (UK) — 40%
  • 3. Saint Petersburg (Russia) — 41%

Russia seems to have a serious traffic problem. As soon as a city starts to grow, so too does the congestion. St. Petersburg and Moscow, the country’s biggest cities, are two of Europe’s three most congested cities.

  • 2. Moscow (Russia) — 44%
  • 1. Bucharest (Romania) — 50%

Worst traffic in Asia

Six Chinese cities are present in the top 10, though the world’s most populous country takes neither of the top two. It’s interesting that Asian cities tend to clump in a congestion rate of their own — all of the ten most congested Asian cities fit in the world’s top 15.

  • 10. Shenzen (China) — 44%
  • 9. Guangzhou (China) — 44%
  • 8. Changsha (China) — 45%
  • 7. Beijing (China) — 46% 
  • 6. Tainan (Taiwan) — 46%
  • 5. Chengdu (China) — 47%
  • 4. Istanbul (Turkey) — 49%

It’s noteworthy that Istanbul is the only city in all these top 10 which reports a slight improvement, though it’s not clear why this is happening.

  • 3. Chongqing (China) — 50%
  • 2. Jakarta (Indonesia) — 58%
  • 1. Bangkok (Thailand) — 61% 

South America, Africa, and Oceania don’t have data for a relevant top 10, but you can check the existing data here.

Small cities

When it comes to smaller cities (<800,000) people, Europe definitely takes the crown. You have to look until the 19th place to find a congested city that isn’t European. While small cities are definitely not as crowded as bigger ones, they too experience growing congestion, which can become a major problem in future years — and already is one in some places, especially in the UK.

Image credits: TomTom.


Living near noisy traffic makes it harder for women to get pregnant


Credit: Pixabay.

Danish researchers say road traffic noise may affect the reproductive health of couples trying to have a baby. According to a recent paper published in Environment International, every 10 decibels (Db) of extra traffic noise around a woman’s home increased the chance the pregnancy took six months or longer by 5 to 8 percent.

The findings were reported by a team led by Jeppe Schultz Christensen of the Danish Cancer Society Research Center in Copenhagen who combed through data on 65,000 women living in Denmark. The participants were involved in the Danish National Birth Cohort which ran between 1996 and 2002. Christensen and colleagues selected all the women who tried to get pregnant during the project that also had traffic noise data available for where they lived.

Previously, a German prospective study found 80 percent of women who are actively seeking to get pregnant do so within six menstrual cycles. Oddly enough, though, if a Danish women lived near a noisy road, her chances of getting pregnant in the six months fell sharply. This link withstood even when factors like poverty levels or nitrogen oxide pollution were taken into account.

However, this association did not seem to be statistically significant anymore for women who took more than 12 months to get pregnant, likely because other factors are affecting fertility in this case.

It’s unclear at this point why noisy traffic might affect women, or couples for that matter, trying to have a baby. It may be that case that noisy streets near a woman’s home cause sleep disturbance which was previously linked to decreased fertility in women but also low-quality semen in men. Constant racket can also activate a system in the brain known to disrupt ovulation. If this is a real causal relationship at stake, we should be worried because noisy traffic is so common in virtually every town and city in the world. Moreover, traffic noise is set to increase as more cars are added to the roads, especially in developing countries. More work is needed before we can assess how worrying this trend may be but in the meantime, couples looking to have a baby should choose bedrooms as far away from the road as possible.

[NOW READ ABOUT] The noisiest and quietest places in America

Living near a crowded street seems to increase dementia risk

A study on six million adults in Canada indicated that living next to a crowded motorway or highway raises dementia risk by 7 percent.

Bangkok, Thailand, is a city notorious for its traffic. Image credits: David McKelvey.19

Main roads are often unpleasant. They’re noisy, crowded, and smelly. A new study wanted to quantify the effect that roads have on our mental health. It concluded that people whose homes were within 50 metres of heavy traffic had a 7 per cent higher risk of developing dementia than those living at 300 meters or more.

The increase was gradual – it was 4 per cent in people living between 50 to 100 metres of a busy road, and 2 per cent in people living between 101 and 200 metres. At distances larger than 300 meters, no significant correlation could be established.

Over the study period, more than 243,000 people developed dementia, 31,500 people developed Parkinson’s disease and 9,250 people developed multiple sclerosis. However, there was no correlation between either Parkinson’s or multiple sclerosis and the proximity to the road.

“Our findings show the closer you live to roads with heavy day-to-day traffic, the greater the risk of developing dementia,” says Hong Chen, at Public Health Ontario, who led the study. “With our widespread exposure to traffic and the greater tendency for people to live in cities these days, this has serious public health implications.”

The study doesn’t explain why this happens, although researchers highlight the connection between nitrogen dioxide and fine particulates (two components of air pollution) and dementia. Still, the main cause remains a matter of debate. Is it the traffic itself that’s causing the problems, or is some other factor – associated or independent – to blame?

“This study has identified major roads and air pollutants from traffic as possible risk factors for dementia, a finding which will need further investigation before any firm conclusions can be drawn about the relative risks of air pollutants for dementia versus other risks such as smoking, lack of exercise, or being overweight,” says David Reynolds, at the charity Alzheimer’s Research UK.

Hong Chen et al (2017). Living near major roads and the incidence of dementia, Parkinson’s disease, and multiple sclerosis: a population-based cohort study. DOI: http://dx.doi.org/10.1016/S0140-6736(16)32399-6

Simulate your way out of (or into) the perfect traffic jam

Traffic jams are a universally miserable experience, no matter when or when they happen. There are numerous factors that can cause one to happen. Sometimes, when the cause is clear, say construction works or a car crash that needs to be cleared away, most of us can keep our frustration in check. But when you’ve been spending the last half hour inching your way to an intersection and then passing through without seeing any apparent reason for the slowdown, it’s much, much worse. The pointlessness of it all is enough to bring you to your boiling point.


But there’s always a cause behind the jam, even if not readily apparent. Computer models like Traffic-Simulation are designed to figure out how each traffic component adds towards this infuriating result. The simulation models various conditions such as the number of trucks or cars on the road, average distance and speed of cars, lane geometry and so forth, to explain how traffic jams develop. The idea is to use the simulations to figure out what might happen if traffic patterns shift, and predict problem areas before they happen.

The website was created by Dresden University of Technology Professor Martin Treiber, and can currently model a single scenario, but more features are planned for the future. The ring road was implemented first to illustrate ‘shockwave’ slowdowns — traffic jams that progress through a line of traffic from the first row of cars, as described in this video from the University of Nagoya, Japan:

So even in perfect conditions, with everyone driving at the same speeds, it’s still really hard for everything to run smoothly (except if you’re an ant). Even something as innocuous as adjusting the number of trucks on the road can cause unbelievable congestion in the simulation. So give it a go, try toying around with the variables to find what it takes to make traffic flow merrily along or create the mother of all traffic congestions.

And next time you’re stuck in traffic you’ll have a much better understanding of exactly “why. aren’t. we. moving. forward?!” Not sure that’s going to make the experience any more pleasant, though.


A fantastic, concise explanation of why traffic jams happen

Tom Vanderbilt, journalist, blogger, and author of the best-selling book, Traffic gave an awesome 20 minute presentation on why traffic jams happen, and why it’s our fault for rush hour traffic.

“[T]he individual driver cannot often understand the larger traffic system,” says Vanderbilt.

The video is definitely worth the watch, but I’ve plucked some of the most interesting points on what’s going on and how it can maybe be solved.

There’s too many cars and not enough road – yeah, this is a pretty ‘Captain Obvious’ thing, but it has to be said before we move onto why it’s mostly our fault. The solution: it’s not about building more roads, but about people using less cars; relying more on public transit would be nice, though the number of cars is not really expected to drop in the nearby future.

People can’t maintain a steady speed. The human inability to maintain a steady, constant speed on the road is responsible for a lot of congestion; this inability has been proven by Japanese researchers, when they asked people to drive constantly in a circle. Jams started appearing out of nowhere, people started braking eratically and everything went to hell.

“You’re not driving into a traffic jam,” says Vanderbilt. “A traffic jam is basically driving into you.” He thinks autonomous cars will reduce this problem considerably.

Self driving cars (which are already legalized in California) could work wonders here, and they could even communicate with each other, keeping a steady, constant distance between themselves – something which humans can’t do, apparently.

We’re also bad when it comes to doing the zipper merge. You’re driving on one of the two lanes, when there’s work in progress on one of them (or they just simply merge); humans are really bad, when it comes to doing this – especially Americans. American drivers typically merge into the right lane as soon as possible and form one long line, probably because they think it’s bad manners to wait until the last moment or because they think they won’t be allowed by other cars to merge late. In fact, says Vanderbilt, traffic would be much better if cars merged at the very end, like one big zipper. This would be safer, quicker, and would reduce road rage (which is continuously growing).

People don’t want to use mass transportation

Vanderbilt’s studies showed that if only 1% of all drivers would use mass transportation, the rest of them would reach their destination almot 20% faster (the 1% would get home faster as well). Even though they hate driving in traffic, even though it’s more expensive and slow, people still want to drive their cars – this is called the ‘car effect’.

“You can’t just assume that as bad as traffic gets that people are automatically going to migrate to mass transportation,” says Vanderbilt.

Some people exhibit driver’s courtesy, some people just take advantage. Self-driving cars could also greatly improve this aspect of driving. Studies have shown some remarkable characteristics of driving, like for example how older drivers are more likely to stop for others. People are more likely to violate traffic rules the closer they are to home — a “familiarity effect.” Also, people tend to drive more closely to bicyclists when they are wearing helmets. Drivers of more expensive cars are more likely to honk in traffic, etc. All these are things we do almost unconsciously, but which all negatively contribute to traffic.

Via The Atlantic Cities