Opinion: The ‘death of the distance’ revisited

This blog post features an opinion piece from PLOS ONE Section Editor in Urban Studies Dr. Diego Rybski about the interplay between shifts in work, friction of distance (or of space), transport patterns, and urban decline. He discusses where opportunities for new insight may be found.

Diego Rybski is a senior researcher at the Potsdam Institute for Climate Impact Research (PIK) and at the Wuppertal Institut. In addition, he is external faculty in the Complexity Science Hub in Vienna and a section editor at PLOS ONE (Urban Studies). Currently, he also serves as the coordinator of the UPon project (Urban Percolation) funded by the German Research Foundation (DFG).

Diego holds a PhD in Physics from Justus-Liebig-Universität (Germany). He was a visiting scholar at Bar-Ilan University (Israel) and a Postdoctoral Fellow at the City College of New York (CCNY). Between 2019 and 2021, he was a Feodor Lynen Research Fellow of the Alexander von Humboldt Foundation at the Department of Environmental Science, Policy, and Management at the University of California, Berkeley.

His research focuses on cities and urban systems—specifically, on cities as complex systems, cities and climate change (mitigation/adaptation), and urban climate and the urban heat island effect. Diego was born in Brazil, grew up between Germany, where his family is from, and Brazil, and is currently based in Berlin (Germany).

Opinion: the ‘death of the distance’ revisited

Digitization, the Internet, and Information & Communications Technology (ICT) dramatically change the way we work [1]. Service is the dominating sector and continues to expand [2]. However, offices – the traditional service-sector working place – are out of fashion. The home office represents a popular working mode, which became necessary during COVID-19 lockdowns and was facilitated by ICT. Technologies, such as video-calls and -meetings, collaborative writing, and cloud services in general, are not only efficient tools but also make personal presence dispensable.

In this post, I discuss a specific example of remote work and contextualize it beyond ICT in relation to urban decline, gravity, and sustainability.

Braesemann et al. [3] investigated a fully remote labor market and studied to what extent remote work connects employers and workers in different countries. Online labor platforms are market places that bring together employers and workers. Since they are online, they facilitate the matching of partners across the globe. For example, a software company based in North America could give a job assignment to a coder located in South Asia – the platform helps them find each other and coordinate the full work pipeline from service contracting to delivery.

The authors reported that – although in principle space-independent – cities draw in remote jobs, whereas rural areas fall behind. This result suggests that traditional agglomeration economies also play a role in the virtual world. A reason might be that workers with in-demand skills attract profitable jobs, while others face intense competition and obtain low wages [3] – just like in the offline world.

Although information and communication technologies have been predicted to bring economic activities to rural areas, the actual development is the opposite, and knowledge spillovers (exchange of ideas among individuals) drive further urbanization [4]. Large cities seem to attract skilled and creative employees, irrespective of their work being online or offline. This is a finding that is also fundamental to urban scaling [5, 6], in that large cities generate, for example, more GDP per capita than small ones (known as increasing returns to scale).

However, ICT changes not only work but also many other aspects of our lives. Streaming has progressively replaced traditional ‘linear’ television as well as the already weakened movie theaters. Moreover, e-commerce (online shopping) drastically reduces the revenues of retail stores. Many of them close, and bankrupt department stores leave (metaphorical) holes in the city centers. Deserted inner cities represent serious challenges, as for example in Germany where pedestrian-only areas have traditionally played a vital role in the cities’ spatial, social, and economic functioning.

These considerations lead to the question: what role does space play and what role will it will play in the future? Historically, city size is limited by the time needed to move within them [7]. In contrast to walking or riding a horse, modern means of transport have enabled the formation of larger cities. Today, ICT makes traveling even more efficient by means of real-time routing or ride-sharing [8]. But what happens if we think ahead about the impacts of digitization, for example where home offices reduce the need to commute, and where remote work is even commute-free?

Space, of course, involves a range of aspects but here I want to focus on one. In geography, one speaks about the friction of distance (also referred to as friction of space ) [7]. In our daily life we go from A to B and the distance, travel time, and costs all represent a friction. Usually, this friction is modeled with a decreasing function: the likelihood to make a trip decreases with the distance.

Often a power-law is used to model spatial flows, where the flow is proportional to the distance raised to a negative power (fA,BdA,B). The exponent γ characterizes the friction of distance under the umbrella of gravitational models [9, 10]. A large value means that distance has a strong effect, meaning that long trips are hard and rare. A small γ means distance has only weak influence, so traveling is easy, and long trips are frequent. In fact, many mobility studies report displacement distributions that follow power-laws [11, Sec.3.3.2]. Similar models are used for all kinds of spatial processes, including communication and interaction between people at a distance.

As a consequence of new ICT developments, we would expect a weakening of the friction of distance (a smaller exponent γ). On the one hand, virtually, we can meet ideally anyone on the globe (γ ≈ 0) and the only restrictions, assuming access to the Internet, are time zones. On the other hand, we do not need to travel, because many things can be done from home (home office, e-commerce) and for these purposes distance becomes essentially irrelevant (γ → 0; strictly speaking, the distance is shifted from the consumers to the vendors/logistics). Last but not least, if we travel, ever more efficient transport permits easy and long trips (for the sake of the argument, we disregard traffic jams).

To date, it is unresolved if and how the γ exponent is changing over time or as a consequence of digitization. Maybe new ICT developments mostly alter the prefactor c in fA,B = c · dA,B. Already in the early Internet age (web 1.0) the death of the distance was anticipated [12].

In 2022, a highly subsidized mobility experiment was conducted in Germany. Intended to compensate for rising costs of living and with the purpose of incentivizing a modal shift from car to public transport, during the months June–August the 9-Euro-Ticket (9ET) was offered. All regional and local public transport could be used across the entire country for 9 Euro per month. From the cost perspective, this ticket implies γ ≃ 0 and people could travel even long distances. And indeed, many people used connections of regional trains to travel across Germany. Because lower-income demographics had the chance to travel, the 9-Euro-Ticket had a social benefit.

It is disputed to what extent the original expectation of stimulating a shift from car to public transport was met but it was estimated that the intervention reduced air pollution by more than six percent [13] and, mostly, the model has been positively evaluated [14]. It is worth mentioning that in 2023 the “Deutschland Ticket” (“Germany Ticket”) was introduced, with the same access but for 49 Euro per month. A big advantage is that city visitors do not need to understand the local ticket pricing system and can use the same ticket in whatever city within Germany. Please note that, in terms of travel time, one can assume larger γ for such tickets than for long distance trains that go faster than regional trains (on large scales).

In order to make mobility more sustainable, it has been proposed to avoid trips or to reduce their length, to shift the means to active transport such as walking and cycling, and to improve the transport technology (avoid, shift, improve; ASI) [15]. The idea of avoiding and reducing trips corresponds to larger γ, i.e. increasing the friction of space. Larger γ, however, contrasts with the idea of the 9ET. As a “consumer” we want to conveniently go anywhere and with little effort. This represents a sort of paradox requiring further consideration.

In summary, by considering selected implications of the digital revolution I argue that while home office and remote work have become popular models, traditional structures such as agglomeration economies persist. The reason could be persisting friction of space, despite transitional ICT developments. There is a research need to understand if and how the friction of distance (represented by the γ exponent) evolves and how sustainability and consumer needs can be reconciled. How do the transport demand and the selection of modes need to change?


[1] H. Kagermann, Change through digitization—value creation in the age of industry 4.0, in Management of Permanent Change, edited by H. Albach, H. Meffert, A. Pinkwart, and R. Reichwald (Springer Gabler, New York, Heidelberg, Dordrecht, London, 2015) Chap. 2, pp. 23–45, https://doi.org/10.1007/978-3-658-05014-6_2.

[2] D. Rybski, P. Pradhan, S. T. Shutters, B. V., and J. P. Kropp, Characterizing the sectoral development of cities, PLoS One 16, e0254601 (2021), https://doi.org/10.1371/journal.pone.0254601.

[3] F. Braesemann, F. Stephany, O. Teutloff, O. Kässi, M. Graham, and V. Lehdonvirta, The global polarisation of remote work, PLoS One 17, e0274630 (2022), https://doi.org/10.1371/journal.pone.0274630.

[4] F. Braesemann, V. Lehdonvirta, and O. Kässi, ICTs and the urban-rural divide: can online labour platforms bridge the gap?, Inform. Commun. Soc. 25, 34 (2022), https://doi.org/10.1080/1369118X.2020.1761857.

[5] L. M. A. Bettencourt, J. Lobo, D. Helbing, C. Kühnert, and G. B. West, Growth, innovation, scaling, and the pace of life in cities, Proc. Natl. Acad. Sci. U. S. A. 104, 7301 (2007), https://doi.org/10.1073/pnas.0610172104.

[6] F. L. Ribeiro and D. Rybski, Mathematical models to explain the origin of urban scaling laws, Phys. Rep. 1012, 1 (2023), https://doi.org/10.1016/j.physrep.2023.02.002.

[7] M. Batty and P. Ferguson, Defining city size, Env. Plan. B 38, 753 (2011), https://doi.org/10.1068/b3805ed.

[8] P. Santi, G. Resta, M. Szell, S. Sobolevsky, S. H. Strogatz, and C. Ratti, Quantifying the benefits of vehicle pooling with shareability networks, Proc. Natl. Acad. Sci. U. S. A. 111, 13290 (2014), https://doi.org/10.1073/pnas.1403657111.

[9] A. T. Philbrik, A short history of the development of the gravity model, Australian Road Research 5, 40 (1973).

[10] R. Curiel Prieto, The gravity model for social systems, in prep. (2023), Compendium of Urban Complexity.

[11] L. Alessandretti and M. Szell, Urban mobility, arXiv.org e-Print archive arXiv:2211.00355 [physics.soc-ph], 10.48550/arXiv.2211.00355 (2022), Compendium of Urban Complexity.

[12] H. Couclelis, The death of distance, Environ. Plan. B 23, 387 (1996), https://doi.org/10.1068/b230387.

[13] N. Gohl and P. Schrauth, Ticket to Paradise? The Effect of a Public Transport Subsidy on Air Quality, Discussion Paper 50 (Center for Economic Policy Analysis (CEPA), 2022), https://doi.org/10.25932/publishup-55846.

[14] A. Krämer, G. Wilger, and R. Bongaerts, Das 9-Euro-Ticket: Erfahrungen, Wirkungsmechanismen und Nachfolgeangebot, Wirtschaftsdienst 102, 873 (2022), https://doi.org/10.1007/s10273-022-3313-2.

[15] D. Bongardt, L. Stiller, A. Swart, and A. Wagner, Sustainable Urban Transport: Avoid-Shift-Improve (ASI), Brochure (Transformative Urban Mobility Initiative, 2019)

Disclaimer: Views expressed by contributors are solely those of individual contributors, and not necessarily those of PLOS.

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Urban Ecology: where the wild meets the city

Urban ecosystems are expanding around the world as people migrate to cities and the human population continues to grow. What happens to other species as these urban ecosystems expand, and how species live and interact

It’s Not Easy Being Green: Assessing the Challenges of Urban Community Gardening


From vertical gardens to succulent gardens to community veggie gardens like the San Francisco garden pictured above, city dwellers all around us have started embracing their (hopefully) green thumbs.  For urbanites in particular, community gardening provides us with much needed “outside time” with likeminded individuals, with the added gift of hyper-local produce available throughout the growing season. These benefits have led to increases in residential and community garden participation in major cities across the US.

While many people are jumping on the garden-fresh bandwagon to reap the obvious, verdant benefits, it is important to consider the potential side effects that come alongside urban farming. Urban soil is not only closer to possible sources of pollution, like traffic and industrial areas, but could also contain residual chemicals from past land use. Residential land previously occupied by industrial buildings has been found to contain dangerous levels of toxins like lead, which can poison residents and contaminate food grown on-site. But it doesn’t take a former factory to contaminate your backyard. Soil can absorb and hold toxins left over from something as small as a previous homeowners dumping of cleaning water down the drain or off the back porch.

Researchers from Baltimore published an article in PLOS ONE earlier this month assessing Baltimore community gardeners’ knowledge of soil contamination risks and explored what steps can be taken to mitigate the dangers of urban pollution in urban gardens.

The authors, hailing from Johns Hopkins, University of Maryland, and the Community Greening Resource Network, conducted interviews with Baltimore’s community garden members, and found that unfortunately, the gardeners generally seem to have low levels of concern about potential contaminants in their soil. Those working in established community gardens were least concerned as they often assumed that any issues with soil contamination had been addressed in the early days of the garden’s use.

Participants listed lead as the most concerning pollutant—likely due to city interventions concerning lead poisoning—with 66% of surveyed gardeners mentioning it as something that would concern them if found in their soil. The study results also indicate that gardeners are more worried about the presence of pesticides and other added chemicals than most other residual chemicals in the soil. Soil quality and fertility even took greater precedence for some gardeners than the presence of contaminants.

By interviewing Baltimore officials knowledgeable about community gardening practices and soil contamination issues, the researchers determined key steps in assuring the safety of gardening sites. Above all, officials suggested the creation of a central source of information related to soil contamination concerns. Similar projects relating to regulation and urban agriculture are already underway in places like Los Angeles, though these resources aim to help residents navigate the maze of confusing legislation related to urban agriculture, and focus less on providing information on how to evaluate the safety of specific plots of land.

The authors suggest other important ways to determine the safety of a garden site, including learning about the site’s past uses and testing the soil for lingering chemicals, both of which might not seem necessary to those untrained in urban planning or chemical analysis. They also recommend that officials in urban areas provide services that will encourage use of these tools and help gardeners find and interpret the results of soil testing or historical research.

In the meantime, the authors suggest limiting exposure to potentially contaminated land. For instance, we should minimize contact with dirt from garden sites by washing our hands and taking off shoes before entering any indoor spaces. Many interviewed gardeners have tried to mitigate this problem by using raised beds, which they believe eliminates concern about contaminants in homegrown vegetables. However, researchers find this method ineffective, and it should not be seen as a fix-all. Raised beds do not prevent contamination from soil around the beds, which can still be ingested or tracked into the home, and surrounding pollutants have been known to blow into beds or seep into the soil from treated wood used to build the structures.

Urban community gardening is a trend that is here to stay, and we have it to thank for fresher local produce, greener surroundings, a greater sense of community, and for the physical, and sometimes therapeutic, activity it provides. The potential dangers associated with gardening in urban areas probably do not outweigh the benefits, as long as gardeners remain diligent and become better informed. Though their study focused on a limited group, this paper’s findings draw attention to the fact that they’re not. So, next time you’re digging into a grassy patch in your backyard with visions of veggies or working in your local community garden, take a minute to think about what you know about your area, discuss past developments with longtime residents, and above all, clean up afterward.

More information on soil testing and good gardening practices can be found on this site from the EPA.

Citation: Kim BF, Poulsen MN, Margulies JD, Dix KL, Palmer AM, et al. (2014) Urban Community Gardeners’ Knowledge and Perceptions of Soil Contaminant Risks. PLoS ONE 9(2): e87913. doi:10.1371/journal.pone.0087913

Image: Tenderloin People’s Garden by SPUR

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Biking the Distance… In 30 Minutes or Less: The Impact of Cost and Location on Urban Bike Share Systems

Citi Bike

Those of us who commute to the PLOS San Francisco office have noticed the emergence of bike share stations cropping up along the San Francisco Bay and on the city’s main drag. And we’re not alone here in San Francisco: the picture above is from the New York City Department of Transportation’s bike share. Around the world, bike share systems, which aim to make bicycles available on a short-term basis to anyone, have experienced massive growth as cities work to decrease gas emissions and encourage people to stay active. However, not everyone is ready to forgo the convenience of four wheels for two just yet. To understand why more people haven’t made the switch from cars to bike share systems, the author of a recently published PLOS ONE paper delved into possible factors affecting our willingness to don a helmet and cycle the distance.

Using publically available data from Washington DC and Boston, Dr. Jurdak, an Australian researcher, conducted a series of statistical analyses designed to examine the impact of bike share system pricing and neighborhood layout on potential bikers. It turns out cost is a major factor for commuters and tourists alike, but distance is not. Although analyses showed a bias towards shorter trips with a tendency towards a peak of 6 minutes—averaging 13 minutes per trip—a sharp drop off occurred in the likelihood of trips right around 30 minutes.

Why the decline at around 30 minutes? In both Boston and Washington DC, trips under 30 minutes incurred no additional cost in the bike share pricing system. Registered users of the bike share, typically commuters, must pay an initial registration fee but have a grace period for all trips completed in less than 30 minutes. Trips extending beyond 30 minutes, however, incur additional fees. In other words, public bicyclers are looking to maximize the distance biked and time spent without incurring any additional cost. Researchers have labeled this as ‘cost sensitivity.’

Statistical analyses also demonstrated the same cost sensitivity in casual users, or those who do not have a monthly or annual membership, and who likely use the bike share system for tourism. However, instead of noting a decline in the likelihood of trips around 30 minutes, Dr. Jurdak found a decline for casual users at around 60 minutes (another price point).

On the other hand, despite sensitivity to cost, bikers appeared less dissuaded from bike trips based on neighborhood layout. Although stations in Boston were on average much closer to other nearby stations than in Washington DC, in general, the trip distribution for both cities was remarkably similar. Perhaps not surprisingly, the most popular routes taken in both Boston and Washington DC were relatively flat.

To encourage more people to cut the car usage and grab a rental bike, Dr. Jurdak recommends that cities consider incentivizing their constituents with what they care about: cost. Modified prices for bike rental during peak hours may decrease car traffic on congested roads; an extension of grace periods for biking difficult topology, like up a steep San Francisco hill, might encourage us to bike even though the clock is ticking to 30 minutes and an incurred rise in price. As cities look to evolve public transportation systems and increase responsible urban mobility, and as city dwellers look for cost-effective ways to get around, bike share programs continue to offer healthy solutions for all, even at 30 minutes or less.

For more on the effects bike share systems are having around the world, check out another recent PLOS ONE paper and the researchers’ blog post on bike webs, visualizations of bike share schemes.


Jurdak R (2013) The Impact of Cost and Network Topology on Urban Mobility: A Study of Public Bicycle Usage in 2 U.S. Cities. PLoS ONE 8(11): e79396. doi:10.1371/journal.pone.0079396

Image 1: Citi Bike Launch by New York City Department of Transportation