Elias’ Lectio Praecursoria

Measuring sustainable accessibility: geospatial approaches toward integrating people and the environment

Lectio Praecursoria in the public examination of Elias Willberg doctoral dissertation on 2nd June 2023

Photo by Christoph Fink

Sustainability means meeting the needs of the present without compromising the ability of future generations to meet their own needs.

Currently, we are compromising that ability. We have exceeded several planetary boundaries, which mark the safe limits for humanity. We are consuming environmental resources at a rate, which would require several planets to sustain. And we, are still on a path where our environmental burden continues to increase.

At the same time, our social challenges remain persistent. In a world of overconsumption, no country has been able to meet the basic social needs of its citizens at a sustainable level of resource use. Inequalities between people are increasing again and growing environmental stresses, like climate change and biodiversity loss only make it harder to achieve social goals.

What we ultimately want, is to reach that safe and just space in the middle, between the ecological ceiling and social foundation where we don’t consume more than what we have, but where we also leave no one behind. Guaranteeing a good life for everyone, without compromising the planet, represents the ultimate goal for our societies.

This goal has guided my thesis, which focuses on spatial accessibility.

For geographers like me, spatial accessibility is one the most important tools to explore social and environmental questions related to human mobility and urban areas. It helps to understand how easily people can get to their important destinations from different areas and with different travel modes. How easily they can interact with other people, activities, and places. How well land use and transport systems are integrated. Usually, we measure accessibility with travel time, but it’s not the only possible way.

The beauty of the accessibility concept is that it’s important both for individuals and collectively. You probably arrived here today with one of these four modes.  Questions of accessibility are present in our everyday choices. How quickly I reach my workplace today? Or in the wintertime? What about my children’s day care? Do I get there on time? Can I go by bike, or do I have to take the car?

Simultaneously, accessibility relates to the sustainability challenges of our time. Accessibility is an essential component of social wellbeing. Transport researchers now widely agree that improving accessibility is necessary to promote social inclusion, reduce social inequalities and promote just cities. Accessibility can explain who has and who has not, where people and services choose to locate, how incomes distribute and how property prices develop. This is why accessibility measures have become an everyday tool for urban and transportation planners.

Accessibility-oriented planning can also provide tools for planners to address our environmental challenges, especially in urban areas.

Transportation sector is currently one of the leading contributors of carbon emissions, air pollution, and a driver of land use change and biodiversity loss. However, if we can design our cities for accessibility, we have a chance to reduce that footprint.

You might have heard about 15-minute city. The essence of this current planning ideal lies in the decades old promise of accessibility. In a city where daily services are located within 15-minute walking distance from home, motorised transport is less needed. Accessibility-oriented planning can improve people’s opportunities while simultaneously decreasing environmental costs and the need to travel. Accessibility-oriented planning can support urban mobility where most travels can be taken on foot, by bike or by public transport.

Unfortunately, in most cities we are still far from short walking access to most daily destinations. After the long history of car-oriented planning and urban sprawl, our transportation systems have been designed so that private car usually provides superior accessibility compared to more sustainable modes. This means that in reality improving accessibility is often achieved by improving the conditions of motorised transport, which comes with a high environmental cost.

This setting presents us a difficult dilemma.

On the one hand, we know how important accessibility is for social wellbeing and justice. Transport researchers increasingly accept that everyone should be guaranteed a reasonable level of accessibility, so that people are able to go to work, hobbies, or grocery stores with decent travel costs.

On the other hand, we also know that opportunities to travel sustainably, by walking, cycling, or public transport are not equally available. Currently, only some of us can live local life. Only some of us can meet their needs without a private car. While we are planning for more sustainable accessibility, we need to be careful that we don’t harm disadvantaged people or benefit only those who are already well-off.

Such trade-offs of accessibility lie at the heart of my thesis.

In my thesis, I take up the challenge of integrating environmental and social goals in accessibility research.

Particularly, I focus on ways how we measure accessibility and how we can develop those ways to enable more sustainable planning.

During the last twenty years, we have seen a tremendous revolution of geographic data and tools. The smart phones in our pockets, the customer cards in our wallets and the sensors distributed everywhere over the urban space now record more geospatial data on cities, environment, transport, and people than we could ever imagine a few decades ago. Advances in computing have also expanded our capacities to use this data to support planning and policy for making better decisions.

This data revolution has provided completely new opportunities for accessibility research. Through new data and tools, we can better understand people’s daily travel opportunities, what places they can reach and what not? We can understand their typical travel patterns, their travel motivations, and their travel barriers. We can improve our accessibility measures to become more sensitive to socio-economic and demographic differences between people as well as to temporal variations in accessibility between hours, days, and seasons. We can better estimate the magnitude of environmental costs from our travel. And we can also focus on how our travel environments are like. Are they healthy or not? Do people want to travel there?

All these advances have particular value for understanding walking and cycling. The modes, which we want and which we need to promote in urban areas, but which have traditionally provided little data to study at urban scale.

By leveraging such advances in geographical research, my thesis, which will be examined today, proposes new ideas and approaches for accessibility research, and more broadly, for urban and transportation research.

This work aims to develop conceptual and methodological approaches to bridge social equity and environmental sustainability in accessibility research.

This work aims to understand the applicability of new geographic data in transport research and to advance place-based accessibility measuring, especially for walking and cycling, to become more sensitive to the variation in time, in the environment and between people

Finally, this work aims to test the new approaches in the Helsinki metropolitan area and evaluates people’s opportunities across the region to travel by walking and cycling. This area provides not only interesting opportunities to study sustainable accessibility, but it is also one of the leading providers of open data, which has greatly benefited my work.

My perspective in the thesis is geographical and I focus on urban areas. I have drawn from several subfields of geography, especially from urban and transport geography and methodologically I rely on geographic information science. My work is also influenced by sustainability science, in which the challenges in ensuring the sustainability of human societies and nature are the core subject matter

The thesis consists of five distinct articles

In my first article, I present a framework for measuring just accessibility within planetary boundaries.  By building on the idea of the ‘safe and just space’, I propose how social and environmental goals could be further integrated in accessibility research, and how their interrelationships, tensions and trade-offs could be made visible and explored.

In my second article, I provide a comparison of cycling data sources. Bike-sharing systems, sports applications, and GPS-trackers, among others, now provide us with more geospatial data on cycling than ever before. But we also know that there are biases and limitations. In the article, I explore what are the benefits and drawbacks of various sources and how well they are able to answer common questions on cycling that planners or researchers might ask.

In my third article, I investigate more closely bike-sharing systems. Using the popular system here in Helsinki as a case study, I explore how inclusively the system has served citizens. I also look into how well the data that the system provides helps us to understand bike-sharing use, bike-sharing users and can it be applied as a proxy for cycling overall.

In my fourth article, I investigate how walking accessibility varies when seasonal changes in the travel environment, opening hours of the shops and differences in people’s walking abilities are considered in the modelling. By focusing particularly on the realities of older people, the study measures how walking speeds vary in summer and winter, and between people. Using these measurements, the study then evaluates who can really reach everyday basic services by walking in the Helsinki metropolitan area?

Finally, in my last article, I develop a novel approach to integrate the quality of the travel environment into the accessibility modelling. By using a novel Green Paths route planning tool that can optimize routes not only based on travel time, but also based on the travel environment, I assess how cyclists are exposed to air pollution, noise, and greenery in Helsinki during their travels. The proposed approach serves planners and researchers in evaluating how healthy, how pleasant, and how accessible good travel environments in the given region are.

The results of my thesis highlight the importance of measuring accessibility holistically and from different perspectives. They call for accessibility researchers to go beyond travel time-based measures toward integrating environmental and social travel costs more fully into the calculation. To go beyond models assuming static conditions and average people toward more dynamic and socially sensitive measures that also represent accessibilities of the disadvantaged and vulnerable. And finally, they call for accessibility researchers to harness the possibilities provided by new geospatial data and tools, but also to use them critically and thoughtfully, and integrating them with existing, more qualitative data sources.

Essentially, I argue that environmental and social goals remain too separate from each other in otherwise rich accessibility and transport research. I argue that the integration of these perspectives is central in making progress toward sustainability in transport. And I argue that we need to move from optimizing time to optimizing wellbeing.

So, can we really reach that safe and just space in transportation? That space, where we don’t consume more than what we have, but where we also leave no one behind?

Ultimately, I think no one knows really, but we must try.

For this effort, my thesis provides a new grain to the growing pile of multivoiced and multiperspective accessibility research, which I believe, can serve all of us in moving to that direction.

Elias Willberg defended her doctoral thesis entitled ”Measuring sustainable accessibility : geospatial approaches toward integrating people and the environment on 2nd June 2023 at the Faculty of Science, University of Helsinki.

Professor Trisalyn Nelson from University of California acted as the opponent and Professor Tuuli Toivonen as the custos. Elias was supervised by Tuuli, Professor Henrikki Tenkanen and Professor Age Poom.

Elias completed her doctoral thesis in the Digital Geography Lab research group under the projects Sporttia Stadiin, URBANAGE, and HOPE, funded by the Amer Cultural Foundation (Sporttia Stadiin) and EU (URBANAGEand HOPE).

The Digital Geography Lab is an interdisciplinary research team focusing on spatial Big Data analytics for fair and sustainable societies at the University of Helsinki.