City Of Zurich Research Articles

Discovering the wild side of urban plants through public engagement

Societal Impact StatementThe Anthropocene has seen declining biodiversity inextricably linked to our societies, values, and choices. This requires ecologists to engage with the public in ecosystems such as cities to learn from and help inform their values and experiences regarding their role in urban nature. This article presents a transdisciplinary citizen science project on spontaneous urban vegetation in the context of urban botany, art‐science, and participatory research that engages with the ecology of cities. We address the interdependence of ecological and social networks, suggesting how plant ecology can become more relevant for society in the Anthropocene, while presenting a specific methodology for engaging the public with urban botany.Summary Cities are socio‐ecological systems that require new ways of thinking and engagement to successfully conserve biodiversity. In this article, we present the citizen science project Where Seeds Fall which was undertaken in the city of Zurich, Switzerland. It was developed in an “ecology with” cities approach seeking to conduct research with the humans living in the ecosystem while learning from and helping inform their values. Our project brings together the perspectives of ecologists, artists, and planners on the three themes of urban wastelands, spontaneous vegetation, and ecological connectivity. It is placed in the context of urban botany, environmental arts and participatory research. Volunteers placed trays of bare soil (without seeds) in their gardens and balconies and monitored what plants arrived and germinated. They then were able to share information about their trays (images, species lists) with one another through a spatially explicit web platform. The project was accompanied by public outreach events and artistic interventions in public space. This article presents the methodology of the project so that it can be replicated elsewhere. Based on the experiences with the project we discuss evolving transdisciplinary perspectives on wild plant biodiversity in cities.

Simulation of price, customer behaviour and system impact for a cost-covering automated taxi system in Zurich

Automated Mobility on Demand (AMoD) is a concept that has recently generated much discussion. In cases where large-scale adoption of an automated taxi service is anticipated, the service’s impacts may become relevant to key transport system metrics, and thus to transport planners and policy-makers as well. In light of this increasingly important question, this paper presents an agent-based transport simulation with (single passenger) AMoD. In contrast to earlier studies, all scenario data (including demand patterns, cost assumptions and customer behaviour) is obtained for one specific area, the city of Zurich, Switzerland. The simulation study fuses information from a detailed bottom-up cost analysis of mobility services in Switzerland, a specifically tailored Stated-Preferences survey about automated mobility services conducted in the canton of Zurich, and a detailed agent-based transport simulation for the city, based on MATSim. Methodologically, a comprehensive approach is presented that iteratively runs these components to derive states in which service cost, waiting times and demand are in equilibrium for a cost-covering AMoD operator with predefined fleet size. For Zurich, several cases are examined, with 4,000 AMoD vehicles leading to the maximum demand of around 150,000 requests per day that can be attracted by the system. Within these parameters, the simulation results show that customers are willing to accept average waiting times of around 4 min at a price of 0.75 CHF/km. Further cost-covering cases with lower demand are presented, where either smaller fleet sizes lead to higher waiting times, or larger fleet sizes lead to higher costs. While our simulations indicate that an AMoD system in Zurich can bring benefits to the users, they show that the system impact is largely negative. Caused by modal shifts, our simulations show an increase of driven distance of up to 100%. All examined fleet configurations of the unregulated, cost-covering, single-passenger, door-to-door AMoD service are found to be highly counter-productive on a path towards a more shared and active transport system. Accordingly, policy recommendations for regulation are discussed.

Response of bats and nocturnal insects to urban green areas in Europe

Animal biodiversity in cities is generally expected to be uniformly reduced, but recent studies show that this is modulated by the composition and configuration of Urban Green Areas (UGAs). UGAs represent a heterogeneous network of vegetated spaces in urban settings that have repeatedly shown to support a significant part of native diurnal animal biodiversity. However, nocturnal taxa have so far been understudied, constraining our understanding of the role of UGAs on maintaining ecological connectivity and enhancing overall biodiversity. We present a well-replicated multi-city study on the factors driving bat and nocturnal insect biodiversity in three European cities. To achieve this, we sampled bats with ultrasound recorders and flying insects with light traps during the summer of 2018. Results showed a greater abundance and diversity of bats and nocturnal insects in the city of Zurich, followed by Antwerp and Paris. We identified artificial lighting in the UGA to lower bat diversity by probably filtering out light-sensitive species. We also found a negative correlation between both bat activity and diversity and insect abundance, suggesting a top-down control. An in-depth analysis of the Zurich data revealed divergent responses of the nocturnal fauna to landscape variables, while pointing out a bottom-up control of insect diversity on bats. Thus, to effectively preserve biodiversity in urban environments, UGAs management decisions should take into account the combined ecological needs of bats and nocturnal insects and consider the specific spatial topology of UGAs in each city.

Syntactical Morphological Histories Analysis on Top-Down Planned and Self-organised Street Networks of Old City Cores

Streets in old city cores not only have important transport and social interaction functions but also reveal the laws of urban and cultural development in a region. Space syntax can improve historians’ understanding of how changes in the shape of habitable space affected people’s lives and urban culture in particular times and places by offering a quantitative description of street patterns; here of two old city cores. The study selects the Altstadt of Zurich (the old city of Zurich) and the Shichahai historical district in Beijing, which have a long history and distinctive street patterns. First, this study digitised the historical maps into axis maps. Then, the study described the characteristics of the syntactic evolution of street networks in two cores over four different development stages. Subsequently, a comparative study of the evolution of different syntactic indicators in the two cases was conducted. Finally, it is concluded that although Shichahai and Altstadt are examples of top-down planned and self-organising areas, their street networks have a similar development trend. However, in their evolution, they show greater differentiation.

Parent Teacher Associations in Turkey and Switzerland: A Comparative Study

Bu çalışmanın amacı Türkiye ve İsviçre’de (Zürih kantonu) okul aile birliği [OAB] kurumunun yapısını ve işleyişini ülkelerin ilgili mevzuatlarını inceleyerek ve her bir ülkeden birer okul müdürü, okul aile birliği başkanı ve öğrenci velisinin görüşlerini karşılaştırarak benzerlik ve farklılıklarını ortaya koymaktır. Nitel bir araştırma olarak tasarlanan bu çalışmada veriler doküman analizi ve yarı yapılandırılmış görüşme formu aracılığıyla toplanmıştır. Araştırmanın çalışma grubu Türkiye’de Afyonkarahisar ili merkez bölgesinden bir ortaokuldan ve İsviçre Zürih kantonu merkez bölgesinden yine bir ortaokuldan 2 okul müdürü, 2 okul aile birliği başkanı ve 2 öğrenci velisinden oluşmaktadır. Araştırmanın sonucunda, her iki ülkedeki okul aile birliği yönetmeliğinde benzerlikler ve farklılıklar bulunmuştur. Bunun yanı sıra görüşmelerden elde edilen sonuçlar aracılığı ile her iki ülkede de ilgili mevzuatın uygulamaya nasıl yansıdığı konusu tartışılmış ve iki ülkedeki okul aile birliği yapıları karşılaştırılmıştır.

The perception of multiethnolectal Zurich German: A continuum rather than clear-cut categories

Since about 2000, the emergence of so-called ‘multiethnolects’ has been observed among adolescents in German-speaking Switzerland; however, a systematic description of these varieties is lacking at present. The few existing perception studies of multiethnolects in other European countries are usually based on two or more predetermined groups that are compared. This paper investigates which labels are used for multiethnolectal Zurich German and how this way of speaking is perceived by adolescents; we adopt a perceptual sociolinguistics approach which focuses on the conceptualizations of lay people rather than on those of linguists.
 In a rating experiment, 40 adolescents listened to short speech samples of 48 pupils recorded in two different schools in the city of Zurich and were asked to rate the speakers on a 7-point Likert scale according to how multiethnolectal they sounded (not at all – very strongly). The results yielded a perceptual continuum rather than a clear-cut binary categorization [±multiethnolectal]. A smaller follow-up experiment with 12 adult raters (using the same stimuli) yielded a highly significant correlation between the mean rating scores of the two groups of raters.

Mapping urban temperature using crowd-sensing data and machine learning

Understanding the patterns of urban temperature a high spatial and temporal resolution is of large importance for urban heat adaptation and mitigation. Machine learning offers promising tools for high-resolution modeling of urban heat, but it requires large amounts of data. Measurements from official weather stations are too sparse but could be complemented by crowd-sensed measurements from citizen weather stations (CWS). Here we present an approach to model urban temperature using the quantile regression forest algorithm and CWS, open government and remote sensing data. The analysis is based on data from 691 sensors in the city of Zurich (Switzerland) during a heat wave using data from for 25-30th June 2019. We trained the model using hourly data from for 25-29th June (n = 71,837) and evaluate the model using data from June 30th (n = 14,105). Based on the model, spatiotemporal temperature maps of 10 × 10 m resolution were produced. We demonstrate that our approach can accurately map urban heat at high spatial and temporal resolution without additional measurement infrastructure. We furthermore critically discuss and spatially map estimated prediction and extrapolation uncertainty. Our approach is able to inform highly localized urban policy and decision-making.

A machine learning-based surrogate model to approximate optimal building retrofit solutions

The building sector has the highest share of operational energy consumption and greenhouse gas emissions among all sectors. Environmental targets set by many countries impose the need to improve the environmental footprint of the existing building stock. Building retrofit is considered one of the most promising solutions towards this direction. In this paper, a surrogate model for evaluating the necessary building envelope and energy system measures for building retrofit is presented. Artificial neural networks are exploited to build up this model in order to provide a good balance between accuracy and computational cost. The proposed model is trained and tested for the case study of the city of Zurich, in Switzerland, and is compared with one of the most advanced models for building retrofit that uses building simulation and optimization tools. The surrogate model operates on a smaller input set and the time required to derive retrofit solutions is reduced from 3.5 min to 16.4 μsec. Results show that the proposed model can provide significantly reduced computational cost without compromising accuracy for most of the retrofit dimensions. For instance, the retrofit costs and the energy system selections are approximated with an average accuracy of R2=0.9408 and f1score=0.9450, respectively. Finally, yet importantly, such surrogate retrofit models may effectively be used for bottom-up retrofit analyses for wide areas and can contribute towards accelerating the adoption of retrofit measures.

Efficiency versus Equity in Spatial Siting of Electricity Generation: Citizen Preferences in a Serious Board Game in Switzerland

Energy transitions around the world will change the spatial fingerprint of the electricity sector, but there is a lack of studies on citizen preferences for siting the future mix of electricity technologies. Using the case of Switzerland in 2035, we present a serious board game to form and elicit citizen preferences for spatial siting of a full mix of electricity technologies and we test this game with 44 participants in the city of Zurich. The game proves to help elicit valid preferences of the participants and lead to measurable learning effects about this complex, multi-dimensional topic. The results show that these 44 participants prefer a diverse mix of renewable technologies for Switzerland in 2035. In terms of siting, these participants consistently choose the efficiency strategy, where new plants are concentrated in the areas where they produce most electricity at least cost, in contrast to the strategy of regional equity, where all Swiss regions would equally build new generation and share the benefits and burdens of the energy transition.

Decline in Distribution and Abundance: Urban Hedgehogs under Pressure.

Simple SummaryHedgehogs have been found in higher densities in urban compared to rural areas. Recent dramatic declines in rural hedgehog numbers lead us to pose the question: how are hedgehogs faring in urban areas? In this study, we examined how hedgehog numbers have changed in the city of Zurich, Switzerland, in the last 25 years. We compared data collected through citizen science projects conducted in 1992 and 2016–2018, including: observations of hedgehogs, data from footprint tunnels, and capture-mark recapture studies. We found that hedgehog numbers have declined by 41%, from the former average of more than 30 individuals per km2, in the last 25 years. In the same time span, hedgehogs have lost 18% of their former urban distribution. The reasons for this decline are still unknown. Intensification of urban buildup, reduction of green space quality, the use of pesticides, parasites, or diseases, as well as increasing numbers of badgers, which are hedgehog predators, in urban areas are discussed as potential causes. Worryingly, these results suggest that hedgehogs are now under increasing pressure not only in rural but also in urban areas, their former refuges.Increasing urbanization and densification are two of the largest global threats to biodiversity. However, certain species thrive in urban spaces. Hedgehogs Erinaceus europaeus have been found in higher densities in green areas of settlements as compared to rural spaces. With recent studies pointing to dramatically declining hedgehog numbers in rural areas, we pose the question: how do hedgehogs fare in urban spaces, and do these spaces act as refuges? In this study, recent (2016–2018) and past (1992) hedgehog abundance and distribution were compared across the city of Zurich, Switzerland using citizen science methods, including: footprint tunnels, capture-mark recapture, and incidental sightings. Our analyses revealed consistent negative trends: Overall hedgehog distribution decreased by 17.6% ± 4.7%, whereas abundance declined by 40.6% (mean abundance 32 vs. 19 hedgehogs/km2, in past and recent time, respectively), with one study plot even showing a 91% decline in this period (78 vs. 7 hedgehogs/km2, respectively). We discuss possible causes of this rapid decline: increased urban densification, reduction of insect biomass, and pesticide use, as well as the role of increasing populations of badgers (a hedgehog predator) and parasites or diseases. Our results suggest that hedgehogs are now under increasing pressure not only in rural but also in urban areas, their former refuges.

Empirical Validation of Bimodal MFD Models

This work attempts to validate the dynamic outputs of bi-modal MFD-based models, also referred to as 3D-MFD models, using empirical data. A previous study (Loder et al., 2017) gathered cars and public transport vehicles data in two different regions of Zurich city and showed that a well-defined 3D-MFD exists by proposing a functional form relating overall travel production to the accumulations of cars and public transport vehicles. This work aims to go one step further with the same data set to investigate if 3D-MFD embedded in dynamic conservation laws can predict the time evolution of the network traffic states. Two different approaches to estimate the inflow demand using outflow and mean speed evolutions are presented. The mean trip lengths are estimated using a network exploration technique. Accumulation-based, trip-based and accumulation-based with outflow delay models are considered in the validation study. It is concluded that a single bi-linear 3D-MFD fit is insufficient to predict the evolution of traffic states accurately. The current work proposes multi bi-linear 3D-MFD fits segregated depending on the time of the day. The proposed approach significantly improved the simulation results, where good correspondence with empirical data is obtained. Finally, it is shown that in multi-modal networks like the city of Zurich, it is essential to consider the effect of public transport vehicles, when considering aggregated simulations. It is also shown that using a 2D-MFD by treating public transport vehicles and private cars alike, result in poor accordance with the field observations.

Parking pricing vs. congestion pricing: a macroscopic analysis of their impact on traffic

This paper focuses on parking pricing and congestion pricing and their short-term effects not only on traffic congestion but also on the potential revenue for a city. We develop a multimodal macroscopic traffic and parking search model based on aggregated data at the network level. Our methodology allows us to analyze how introducing parking pricing inside a network, or a congestion toll combined with a park and ride (P+R) scheme can affect the drivers’ decision between entering the network by car or using P+R. This decision directly influences the number of drivers using P+R, and this impacts, in turn, the traffic performance. We illustrate our proposed framework in a case study of an area with a high parking demand for public parking spaces within the city of Zurich, Switzerland. Results show that parking pricing combined with P+R is indeed a viable option compared to congestion pricing for improving traffic performance.

Road Traffic and Aircraft Noise as Drivers of Environmental Protest?

This article investigates whether and to what extent unfavorable local environmental conditions furnish an important motivator for environmental protest. We do so using individual-level data on objective and subjectively perceived residential road traffic and aircraft noise pollution, pertaining to the cities of Mainz (Germany) and Zurich (Switzerland). By referring to fine-grained noise data, we are able to test the predictive power of grievances and self-interest in explaining protest participation more stringently than has been the case in most previous studies. Theoretically, our study is inspired by Klandermans’ socio-psychological framework of political protest, the pressure-response approach, the self-interest perspective, and the collective-interest model. Our empirical findings only partially confirm the grievances assumption that unfavorable local environmental conditions in the form of residential road traffic and aircraft noise stimulate environmental protest. Noise caused by airplanes seems to be more “protest-inducing” than that produced by road traffic. It is not so much the objectively measurable noise level as its subjective perception and evaluation that are deciding factors. However, in line with Klandermans’ protest framework and other theories of political protest, there are more influential drivers of environmental protest, such as environmental concerns and a left-wing political ideology. Thus, the effects of residential road traffic and aircraft noise turn out to be relatively moderate. Ultimately, this means that our tailored measures of grievances corroborate a relatively well-established finding of protest research.

Identifying Changes in Bicycle Accident Trends Using GIS and Time Series Information in the City of Zürich

In order to be effective, road safety officers must have a complete overview of the accidents in their area of responsibility, including information pertaining to the location and severity of the accidents, and how the number of accidents are developing over time. Ideally, this information is stored in a Geographic Information System (GIS) enabled database, which helps to facilitate data processing and analysis, which enables improved understanding of the reasons for the accidents and the proposals of how to improve road safety. This paper presents a case study based on accident reports from the Zurich City Police. Using a joint GIS and time series analysis based on negative binomial regression, the data is analyzed to identify trends in accident development for several accident subgroups (e.g. bicycle accidents, senior citizen accidents, e-bike accidents) and specific locations. The subgroup of bicycle accidents will be discussed in more detail. The time series analysis is corrected for exposure (e.g. the increasing number of e-bikes) and forecasts the number of accidents which are likely to occur in the future. Significantly higher numbers of accidents than those expected serve as an early warning that further investigation, leading to possible interventions, is required. The case study shows that with this information, it is possible to identify both geographical areas and accident subgroups that have deviating patterns in accident numbers, and should be further investigated. For bicycle accidents, 4 out of 12 districts exceed the average accident trend by over 95 and 3 districts have an accident number that is over 10 higher than that district's forecast, with the highest being 33 above the already increasing accident trend. Other accident subgroups are presented in summary form. The results of the analysis allow consistent and automated analysis across all potential areas for improving road safety, helping to focus the efforts of road safety managers on those areas where their efforts are most effective.

Filling the weight gap: Estimating body weight and BMI using height, chest and upper arm circumference of Swiss conscripts in the first half of the 20th century

We estimate weight and BMI values based on height, chest circumference, and mid upper arm circumference measures of Swiss conscripts in the city of Zurich for each year between 1904 and 1932. Height, chest circumference, and mid upper arm circumference were measured each year from 1904 to 1951. Body weight is available from 1933 to 1951. We used prediction equations from the literature, and also developed our own equations, which we tested and validated on the dataset from 1933 to 1951. We used a representative sample of usually 19-year-old Swiss males (N = 88,792, coverage > 88 %). There was an increase in average height and chest circumference between 1904 and 1951. During both world wars, chest circumference, mid upper arm circumference, weight, and BMI decreased, while height stagnated. Overall mean weight and BMI increased from 1904 to 1951, but decreased during the Great Depression. After World War II, weight quickly returned to the pre-war and pre-Great Depression level, while BMI had not reached the 1933 level by 1951. Average weights of the lower and middle socioeconomic groups were catching up with average weight of the upper socioeconomic group from 1904 to 1951. The convergence in height is less pronounced. Finally, we show that it is possible to accurately predict mean weight and BMI from other anthropometric measurements. We suggest that our estimation approach could be replicated for other historical populations to obtain more information on how nutritional status changed over time.

Designing a large-scale public transport network using agent-based microsimulation

Abstract An agent-based simulation framework is extended to design efficient large-scale public transport networks. It goes beyond existing approaches by incorporating a dynamic demand response towards both changes in the network and exogenous factors. The framework is based on an agent-based (MATSim) simulation and tested for the city of Zurich. In contrast to most existing public transport network optimization approaches, this framework is part of a city-level, multi-modal transport simulation tool. Compared to the existing public transport system, it proposes a sparser network with smaller vehicles and substantially higher frequencies. By doing so, the approach predicts a higher transit ridership at a lower level of subsidies. Moreover, it reliably identifies corridors for potential capacity upgrades. The method may help transport planners to assess their existing public transport networks and to plan public transport infrastructure for the era of automated vehicles.

Building Footprint Generation by Integrating Convolution Neural Network With Feature Pairwise Conditional Random Field (FPCRF)

Building footprint maps are vital to many remote sensing applications, such as 3D building modeling, urban planning, and disaster management. Due to the complexity of buildings, the accurate and reliable generation of the building footprint from remote sensing imagery is still a challenging task. In this work, an end-to-end building footprint generation approach that integrates convolution neural network (CNN) and graph model is proposed. CNN serves as the feature extractor, while the graph model can take spatial correlation into consideration. Moreover, we propose to implement the feature pairwise conditional random field (FPCRF) as a graph model to preserve sharp boundaries and fine-grained segmentation. Experiments are conducted on four different datasets: (1) Planetscope satellite imagery of the cities of Munich, Paris, Rome, and Zurich; (2) ISPRS benchmark data from the city of Potsdam, (3) Dstl Kaggle dataset; and (4) Inria Aerial Image Labeling data of Austin, Chicago, Kitsap County, Western Tyrol, and Vienna. It is found that the proposed end-to-end building footprint generation framework with the FPCRF as the graph model can further improve the accuracy of building footprint generation by using only CNN, which is the current state-of-the-art.

Betweenness-accessibility: Estimating impacts of accessibility on networks

Accessibility is a central concept in transport geography research that has been described as a holistic measure of transportation and land use systems. This concept has numerous implementations, but virtually all share the way accessibility is measured as an attribute of pairs of origins and destinations. Borrowing from concepts in network science, in this paper we propose a new centrality measure called betweenness-accessibility. This measure couples the familiar betweenness indicator of social networks with the geographical concept of accessibility. Betweenness-accessibility is useful to estimate the impacts of accessibility on networks as potential for interaction is reflected on them. The new measure is illustrated using a reproducible example. In addition, an application to vulnerability analysis in the city of Zurich, Switzerland, provides an empirical case study to showcase the usefulness of betweenness-accessibility.

Psychological restoration in urban gardens related to garden type, biodiversity and garden-related stress

In the context of increasing urbanization, gardens as a form of urban greenspace are an important resource for the psychological restoration of urban dwellers, while underpinning urban biodiversity and delivering ecosystem services. However, the links between restoration, garden type and biodiversity are not fully understood. In this interdisciplinary study we aimed to identify how the self-reported restoration of gardeners was related to three factors: garden type (domestic vs. allotment gardens), number of plant species in the garden (a dimension of biodiversity) and garden-related stress for gardeners. We analyzed cross-sectional data of approx. 300 leisure gardeners in the city of Zurich, Switzerland, using an analysis of spatial autocorrelation, t-tests of differences of means between garden types and a structural equation model (SEM).The results indicated that being an allotment gardener was associated with higher levels of restoration compared to domestic gardeners. The SEM suggested that restoration was positively related to the number of plant species by way of the perceived restorativeness of the garden. Garden-related stress or negative affect occurred among a number of gardeners and was negatively related to the restoration outcome. This suggests that the negative effects of gardening should be considered in future studies on greenspace and restoration.In the face of shrinking urban greenspace, our study suggests that urban planners could better utilize the benefits of urban gardens, e.g. to reduce income-related health inequalities by providing gardens to residents with lower socio-economic status or to address public health and ecological issues by promoting plant-species rich gardens.

Cover

Front cover: Overgrown allotment garden lot in the city of Zurich, Switzerland, with colored bowl traps to capture flower-visiting insects (Photo by David Frey).