Does building more roads create more traffic?

Tunnel vision: the claim that more roads equals less congestion fails to acknowledge the wider picture. Image: Martin Fisch via Flickr.

Congestion is a major source of frustration for road users and has worsened over time in most cities. Different solutions have been proposed, such as introducing congestion charging (a favourite of transport economists) or investing in public transport. The solution put forward most often is to build more roads. But does this approach actually work?

A recent study in the United States identified Los Angeles, Honolulu and San Francisco as the top three most gridlocked cities in the United States. All of these cities use almost exclusively road-based solutions to transport citizens. Meanwhile, China has increased its expressway network from 16,300 km in the year 2000 to around 70,000 km in 2010. Yet the average commute time in Beijing increased by 25 minutes between 2012 and 2013 to 1 hour and 55 minutes.

So why do residents of these cities not live in a driving utopia, despite their huge amounts of road capacity? 

Induced demand

The first thing to get your head around is a concept called induced demand.

Think about the street where you live. If a new road makes driving to work quicker, you may benefit from that.

But this reduced travel time might be enough to encourage two other people in your street to start driving; and two more people in the next street; and two more people in the street after that; and so on. Very quickly, the drive to work takes just as long as it ever did.

In transportation, this well-established response is known in various contexts as the Downs-Thomson Paradox, The Pigou-Knight-Downs Paradox or the Lewis-Mogridge Position: a new road may provide motorists with some level of respite from congestion in the short term, but almost all of the benefit from the road will be lost due to increased demand in the longer term.

To add insult to injury, while more roads may solve congestion locally, more traffic on the road network may result in more congestion elsewhere. In Sydney, for example, the WestConnex may improve traffic conditions on Parramatta Road, but may worsen congestion in the city as a whole.


Weakest links

Congestion is determined by the weakest links in the road network. If road capacity expansion does not involve widening of these bottleneck links, congestion may simply move to another part of the network without solving the congestion problem. Moreover, it could potentially make congestion across the network even worse.

The Braess Paradox is a famous example in which building new roads in the wrong location can lead to longer travel times for everyone, even without induced demand, because new roads may lead more car drivers to the weakest links in the network. The reverse may also be true: removing roads may even improve traffic conditions.

This paradox occurs because each driver chooses the route that is quickest without considering the implications his or her choice has on other drivers. Car drivers only care about the number of vehicles in the queue in front of them and do not care about vehicles queueing behind them. This is a classic problem in game theory, very similar to the type for which John Nash was awarded a Nobel Prize.

Building, widening or duplicating toll roads and freeways may just induce more people to choose cars over public transport. Image: KRoock74 at Wikimedia Commons.

What does the data say?

One US study has shown a strong relationship between the amount of new road length and the total number of kilometres travelled in US cities, a finding the authors of that study termed “the fundamental law of road congestion”.

Similar findings are reported in Spain and in the United States, where even major road capacity increases can actually lead to little or no reduction in network traffic densities. It has also been found to exist in Europe, where neglecting induced demand has led to biases in appraising of environmental impacts as well as the economic viability of proposed road projects.

New South Wales Premier Mike Baird’s successful re-election campaign promised motorists more roads and less traffic.

In Sydney, there is similar evidence from traffic volumes crossing the harbour. The Sydney Harbour Bridge was carrying a stable traffic volume of around 180,000 vehicles per day from 1986 to 1991. The Sydney Harbour Tunnel opened in 1992, and the total volume of traffic crossing the harbour increased in 1995 to almost 250,000 vehicles per day. This 38 per cent increase in traffic can be attributed to induced demand and not to population growth (which was around 4 per cent during this period).

Empirical observations have also confirmed the existence of the Braess Paradox. For example, in 1969 a new road was built in Stuttgart, Germany, which did not improve the traffic conditions. After closing the road again, congestion decreased.

Similar observations in which road closure led to improved traffic conditions have been observed in New York City, where upon closing 42nd street (a major crosstown street in Manhattan) it was observed that traffic was significantly less congested than average.

A recent experimental study confirmed that this paradox still exists by showing that expanding road capacity can result in worse traffic conditions for everybody.

The theory of induced demand is accepted by a large majority, but not by everyone – the authors of a 2001 paper argued that induced demand does not exist. However, UK researchers Goodwin and Noland have criticised this study.

In isolation, building more roads can certainly improve traffic conditions, but these effects may only be local and short run. Roads alone do not solve congestion in the long term; they are only one (problematic) tool in a transport management toolkit.

Matthew Beck is a Senior Lecturer in Infrastructure Management, and Michiel Bliemer Professor in Transport and Logistics Network Modelling. Both work at the University of Sydney. 

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

 
 
 
 

To see how a city embraces remote work, just look to Helsinki

A deeply rooted culture of trust is crucial to the success of remote work. (Sean Gallup/Getty Images)

When I speak to Anssi Salminen, an account manager who lives an hour outside Helsinki, he’s working from a wooden platform on the edge of a Finnish lake. With a blanket laid out and his laptop set up, the sun low in the sky, Anssi’s remote work arrangement seems blissful. 

“I spend around half of my time working somewhere else other than the office,” he says. “I can work from home, or on the go, and I also travel to the Netherlands once a month and work from there.

“The emphasis in my work has always been that it doesn’t matter when or where I work, as long as I get things done.”

For many people around the world, the shift to remote work was sudden, sparked by the coronavirus pandemic. Finland, however, is finding the transition much less significant. Before Covid-19, the Nordic nation already displayed impressive levels of remote working, with 14.1% of its workforce reporting usually working from home. Only the Netherlands has a comparable percentage of remote workers, while the UK lagged behind at 4.7%, and the US’s remote workforce lingered at around 3.6%

Anssi works for one of many Helsinki-based companies that offers its employees flexible policies around when and where they work. That arrangement is in part due to the Finnish capital’s thriving start-up scene. In spite of being a relatively small city by global standards it is home to over 500 technology start-ups. These companies are leading the way when it comes to keeping employees connected wherever they choose to work.

“Our company has a completely location-free working policy,” says Kasper Pöyry, the CEO of Helsinki-headquartered software company Gapps. “All meetings are made available for online participants and facilitated accordingly. Some employees have worked extensively from abroad on a working holiday, whilst others prefer the comfort and social aspects of the well-stocked office. Whatever works for our employees is what works for the company.”

Like Gapps, many Helsinki-based firms are deeply preoccupied with providing the necessary technology to attract talent in a vast and sparsely populated country. Finland has only 15 inhabitants per square kilometre, and companies understand that in order to compose teams of specialised expertise, they may have to seek talent outside of the city. Local governments take a similarly proactive stance toward technological access, and Helsinki offers free, unrestricted, high-speed Wi-Fi from city-wide hotspots, while the country as a whole boasts some of the best coverage in Europe. 

But encouraging remote work isn’t just about optimising the potential of Finland’s workforce – companies in Helsinki also recognise that flexibility has clear benefits for both staff and employees. 

“The idea of a good work-life balance is ingrained in Finnish culture,” says Johannes Anttila, a consultant at organisational think tank Demos Helsinki. “It goes back to our rich history of social dialogue between labour unions and employers, but also to an interest in delineating the rules of working life and pushing towards people being able to enjoy their private life. Helsinki has been named the best city in the world for work-life balance, and I think that this underlies a lot of the mentality around remote work.” 

For Peter Seenan, the extent to which Helsinki residents value their free time and prioritise a work-life balance prompted his move to the city ten years ago. He now works for Finnair, and points to Finland’s summer cottages as an example of how important taking time to switch off is for people in the country. These rural residences, where city residents regularly uproot to enjoy the Nordic countryside, are so embedded in Finnish life that the country boasts around 1.8 million of them for its 5.5 million residents

“Flexible and remote work are very important to me because it means that I don’t feel like I’m getting stuck in a routine that I can’t control easily,” he says. “When I’m working outside of the office I’ll go down to my local sauna and go ice swimming during the working day, typically at lunchtime or mid-morning, and I’ll feel rejuvenated afterwards… In winter time especially, flexibility is important because it makes it easier to go outside during daylight hours. It’s certainly beneficial for my physical and mental health, and as a result my productivity improves.”

The relaxed attitude to working location seems to pay off – Finland is regularly named the happiest country in the world, scoring highly on measures such as how often its residents exercise and how much leisure time they enjoy. With large swathes of unspoiled countryside and a national obsession with the outdoors, sustainability is at the forefront of its inhabitants’ minds, leading to high levels of support for measures to limit commuting. In January, Finland passed a new Working Hours Act, the goal of which was to help better coordinate employee’s work and leisure time. Central to this is cementing in law that employees can independently decide how, when, and where they work.

Yet enacting the new ruling is not as simple as just sending employees home with their laptops. For Kirsimarja Blomqvist, a professor of knowledge management at LUT University, perhaps the most fundamental feature that remote work relies upon is a deeply rooted culture of trust, which Helsinki’s residents speak of with pride. The anecdotal evidence is backed up by data which suggests that Finland boasts one of the highest levels of trust and social cohesion in Europe, and equality and transparency have always been key cornerstones of political thought in the country.

“Trust is part of a national culture in Finland – it’s important and people value it highly,” she explains. “There’s good job independence, and people are valued in terms of what they do, not how many hours they work for. Organisations tend to be non-hierarchical, and there is a rich history of cooperation between trade unions, employers, and employees to set up innovative working practices and make workers feel trusted and valued. 

“It’s now important that we ensure that this trust can continue to be built over technology, when workers might have been more used to building it face-to-face.”

As companies begin to look hopefully toward a post-Covid future, the complexities of remote work are apparent. Yet amid issues of privacy, presenteeism, and social isolation, the Helsinki model demonstrates the potential benefits of a distanced working world. The adjustment to remote work, if continued after the crisis, offers a chance to improve companies’ geographical diversity and for employers to demonstrate trust in their workforce. On these issues, Blomqvist believes other cities and employers can learn a lot from Helsinki.

“People are now beginning to return to their workplaces, but even as they do they are starting to consider the crisis as a jumping point to an even more remote future,” she says. “The coronavirus pandemic has been an eye-opener, and people are now interested in learning from Finland’s good practices… We are able to see the opportunity, and the rapid transition to remote work will allow other countries to do the same.”

Katie Bishop is a freelance writer based in Oxford.