Monthly Archives: May 2025

Ane defends her PhD: Network analysis of Denmark’s bicycle infrastructure

Big congratulations to Dr. Ane Rahbek Vierø – she defended her thesis yesterday, on Network Analysis of Denmark’s Bicycle Infrastructure: Data & Infrastructure for All? 🥳 🎓 We are proud about Ane’s brilliant scientific accomplishments that have also started to have a big practical impact on bicycle network planning nationally and internationally.

Supervisor: Michael Szell
Committee: Michele Coscia, Trine Agervig Carstensen, Trivik Verma

Read her thesis here: https://en.itu.dk/Research/PhD-Programme/PhD-Defences/PhD-Defences-2025/May/Ane-Rahbek-Vier_

The thesis spans 5 papers that advance data and network analysis of bicycle infrastructure, from the 3 perspectives of 1) data foundations, 2) spatial patterns of bikeability, 3) linking research and planning. Unique achievements are the analysis of a whole country’s (Denmark’s) bicycle infrastructure and network, with the creation of open source tools. The thesis also concludes a project funded by the Danish Ministry of Transport / Road Directorate.

In her research Ane reveals that bicycle infrastructure data often suffer from inconsistencies and low quality, reflecting historical underinvestment in active mobility data. This data heterogeneity creates an information gap and necessitates extensive preprocessing, creating barriers to cycling research and planning. Additionally, she finds that bikeability and access to low-stress cycling infrastructure are highly spatially clustered, with substantial disparities between urban and rural areas. While urban areas generally benefit from better cycling conditions, large segments of the Danish population are deprived of the advantages of active mobility. The geographical differences in bicycle infrastructure access and data quality highlight the need for a spatial perspective in cycling research. Finally, she demonstrates that data-driven tools can aid bicycle planning by generating insights into complex planning questions that involve large geographical areas.

With her PhD completed, Ane has already started a research position at Roskilde University, where she remains at least for the short term. We are both sad to “lose” Ane with her friendly, collegial spirit and unreplaceable skill set, and happy for her success and positive impact in the world. That being said, we are not finished collaborating, and will always be happy to see Ane around.

Paper & Viz: Analysis of Denmark’s whole bicycle network

Today we published the paper which marks the Grand Finale of Ane’s PhD, which she will defend this thursday, May 22nd, in Auditorium 2 at ITU: https://en.itu.dk/Research/PhD-Programme/PhD-Defences/PhD-Defences-2025/May/Ane-Rahbek-Vier_

Her thesis is “Network Analysis of Denmark’s Bicycle Infrastructure: Data & Infrastructure for All?”, of which an important part is the paper:

Network Analysis of the Danish Bicycle Infrastructure: Bikeability Across Urban–Rural Divides, by A.R. Vierø and M. Szell, published in Geographical Analysis

To bridge the gap between urban and rural cycling research, we analyze the bicycle network of Denmark, covering around 43,000 km2 and nearly 6 million inhabitants. We divide the network into four levels of traffic stress and quantify the spatial patterns of bikeability based on network density, fragmentation, and reach. We find that the country has a high share of low-stress infrastructure, but with a very uneven distribution. The widespread fragmentation of low-stress infrastructure results in low mobility for cyclists who do not tolerate high traffic stress. Finally, we partition the network into bikeability clusters and conclude that both high and low bikeability are strongly spatially clustered. Our research confirms that in Denmark, bikeability tends to be high in urban areas. The latent potential for cycling in rural areas is mostly unmet, although some rural areas benefit from previous infrastructure investments. To mitigate the lack of low-stress cycling infrastructure outside urban centers, we suggest prioritizing investments in urban–rural cycling connections and encourage further research in improving rural cycling conditions.

With the paper comes an interactive visualization of the whole bicycle network of Denmark! Check it out at: bikenetwork.dk

This achievement also marks the conclusion of all our “deliverables” for the Vejdirektoratet grant by the Danish Ministry of Transport which financed Ane’s Phd.

If you are around ITU, don’t miss Ane’s defense on thursday!

Two new NERDS papers: Bias in LLM populations, recommending routes

We have two new publications out!

  1. Emergent social conventions and collective bias in LLM populations, by Ariel Flint Ashery, Luca Maria Aiello, and Andrea Baronchelli, published in Science Advances. Barplots of estimation of individual LLM bias vs. the collective bias they exhibit when playing the naming game
    We explore the collective behavior of LLMs starting from social conventions, the fundamental building blocks of coordinated societies. We used the naming game, a well-established framework that has been applied for decades to study conventions in humans. We found that LLM populations can spontaneously develop shared conventions through local interactions. These interactions can produce collective biases, invisible at the individual level, raising important considerations for AI alignment. Small committed minorities can trigger tipping points, steering the entire group toward new conventions—a dynamic well known in human societies
  2. The experience of running: Recommending routes using sensory mapping in
    urban environments, by Katrin Hänsel, Luca Maria Aiello, Daniele Quercia, Rossano Schifanella, Krisztian Zsolt Varga, Linus W. Dietz, and Marios Constantinides, published in the International Journal of Human-Computer Studies.Map of London with several pairs of alternative running trajectories (urban routes plotted in red, scenic in blue)
    We set out to build running routes not around distance, but around how people feel: before, during, and after a run. We surveyed 387 runners and found that not everyone wants the same kind of run. Some seek quiet and greenery; others thrive on the buzz of people and traffic. Their preferences often match their personality. Runners who prefer scenic paths (quiet, green, and natural) tended to score higher in neuroticism. Those who preferred urban paths (lively and full of people) were more likely to be extroverted. Then, we built a routing engine. Using millions of geotagged Flickr photos and open London data, we scored streets for beauty, noise, safety, and surface quality. We tested the engine on hundreds of 5-km London loops. Most runners preferred the scenic routes.

Two new NERDS papers published at CHIIR 2025

We have two new publications out at CHIIR 2025 in Melbourne (Proceedings of the 2025 ACM SIGIR Conference on Human Information Interaction and Retrieval):

  1. Exploring the Zero-Shot Known-Item Retrieval Capabilities of LLMs for Casual Leisure Information Needs, by T. Bogers, M. Gäde, M. Hall, M. Koolen, V. Petras, M. Skov, published in CHIIR 2025
    We compared four LLMs on their capability to answer a specific type of complex search task: known-item requests from casual leisure domains. We constructed a test collection by gathering known-item requests for books, games and movies from online forums along with verified answers by the original requester. We prompted four LLMs multiple times with the same prompt and analyzed the results with respect to accuracy and the degree to which answers were fabricated by the LLM. Our results show that LLMs are not particularly effective in fulfilling these complex casual leisure needs, but there are are big differences between LLMs and across domains.
  2. From Queries to Candidates: Exploring Search and Source Interaction Behavior of Recruiters, by T. Bogers, M. Kaya, M. Gäde, published in CHIIR 2025

    Recruitment is a professional search domain that has been largely overlooked in IR research, even though better support of recruiters could have a big impact on job seekers, companies and society as a whole. In this paper, we analyze the search formulation and source selection behavior of the recruiters at one of Scandinavia’s largest job portals and recruitment agencies using search logs for close to 18,000 recruitment search tasks. We provide an analysis of the search sessions of recruiters in terms search tactics, query operators, query length, term re-use and filter usage, and break down their behavior both by task type and task complexity. We also relate their short-term tactics to different learning stages in the search process and investigate their influence on search success. We find that identifying and assessing relevant candidates for a job posting is a complex task: recruiters usually submit multiple queries during sessions that can last for hours and that increase in complexity. Recruiters all spend more time per query as their session progresses. We also observed query reformulation strategies that indicate distinct patterns of knowledge gaining during sessions. Relating these tactics to positive responses from candidates we aim at predicting successful strategies.