Olle Järv is a human geographer who recently defended his PhD thesis entitled “Mobile phone-based data in human travel behaviour studies: New insights from a longitudinal perspective“, earning a joint degree from the University of Tartu and Ghent University.
The contemporary world is seeing a constant increase in the mobility of people, goods and information around the globe, which makes societies ever more complex, dynamic, and fluid in nature. Hence, how to maintain the operation of such a system and plan environmentally, socially, and economically sustainable societies in these circumstances? To do so, planners and policymakers need to go beyond traditional information sources and focus on human spatial behaviour at the individual level.
In developing urban regions it is essential to monitor urban processes and individual daily movement trajectories continuously. Image credit: Olle Järv
Personal spatial mobility and society
Individual spatial mobility is comprised of a complex pattern of movements and activities in space and time. It is the outcome of the continuous interplay between an individual, other people, and the surrounding environment and society at large. In addition to external factors, such as the layout of urban structure, legislation, or societal norms, spatial mobility is also determined by one’s social networks and is further amplified by information and telecommunication technologies (ICT).
Individual travel behaviour has become more flexible and fragmented in space and time, and the objective of spatial mobility may well be the travel itself as an activity. Scholars argue that individual mobility is positively related to an individual’s subjective well-being, creation of social status, and the premise for innovation. Furthermore, ‘being mobile’ has become an established ideology in the contemporary world, and is functioning as a new form of capital.
However, the increase of personal mobility also has a negative impact on the surrounding environment through the growth of excessive travel, CO2 pollution, and dissatisfaction with the quality of life. No less important, individual spatial mobility is also a factor for social inequality between people. Hence, personal spatial mobility research is essential for understanding and solving a myriad of different societal issues.
For instance, the knowledge of personal mobility helps urban planners better manage urbanisation and excessive land use, as well as design better neighbourhoods. Transportation planners are able to develop intelligent transportation systems, improve accessibility, and alleviate traffic jams. Comprehensive knowledge of individual spatial mobility enables us to understand thoroughly the phenomenon of segregation and to reduce the deepening spatial divisions between social groups.
The knowledge of personal mobility helps urban planners better manage urbanisation and excessive land use, as well as design better neighbourhoods. Image credit: Olle Järv
Practical applications from bridge planning to segregation
My thesis sought to ascertain how the proposed methodology that is based on mobile phone data can help us understand human spatial mobility, and how it can be applied to provide valuable knowledge on social processes and phenomena.
One application is to locate home and working locations at the neighbourhood level, and assess the distribution of the population and short-term population mobility dynamics up to the country level. For example, in a country where demographic processes are developing fast and the official records of population distribution do not reflect the actual situation, this kind of up-to-date information can provide an essential starting point for urban planners and policymakers in making adequate decisions.
In the case of developing countries, where reliable register data are not available, this proposed methodology may be the best or only reliable tool for monitoring population dynamics. Short-term population dynamics on a daily, weekly, and monthly basis enables both private businesses to assess and adapt their market strategies as well as the public sector to provide public services by taking into account the variability of demand.
Being able to extract and locate people’s homes, workplaces and other important daily activity locations can provide additional knowledge for transportation planning. By linking individuals’ homes and workplace locations and distributing this info into origin-destination movement matrices we can estimate traffic flows in the transportation network.
Furthermore, we can assess the composition of road users and the purpose of their trips. This additional information is a valuable source to monitor and assess traffic flowscost-effectively, such as commuting dynamics within urban regions, or to develop road network improvements. For example, this methodology was used in planning the new bypass bridge in the south-east of Tartu and the new section of the Tallinn-Tartu highway to be built in a few years. This methodology also helps to optimise the public transportation system.
Mobile phone-based data can help estimate traffic flows based on actual mobility of individuals, which is more effective than dealing with the consequences and broadening roads. Image credit: Olle Järv
The great potential of this type of methodology is only now being acknowledged in social sciences. For example, it allows one to delve into the phenomenon of segregation by applying a person-based approach.
While the preferred language of communication with the mobile operator was used as a proxy for ethnicity, it was possible to reveal socio-spatial inequalities at the individual level between Estonian speakers and Russian speakers living in Tallinn. The results suggest significant ethnic differences in human spatial mobility on a daily basis, whereas the difference increases when looking all the spatial mobility people conduct during a one-year period.
Results confirm the understanding that Russian speakers tend to visit places where the Russian-speaking minority lives, whereas Estonian-speakers visit different places more equally throughout Estonia. In addition, results indicate that personal spatial mobility for Russian speakers is significantly more concentrated compared to that of Estonian speakers. On average, a Russian speaker visits far fewer activity locations and the extent of his or her activity space is significantly smaller compared to the spatial behaviour of an Estonian speaker.
Although this study did not aim to reveal the underlying causes of such ethnic differences, the study already demonstrates the importance of delving into person-based segregation to better understand the segregation phenomenon in general.
Implementation and privacy of mobile phone-based data
The implementation of ICT-based sensor technologies (mobile phone positioning, GPS, Bluetooth, Wi-Fi) helps us to understand and map human mobility better. Because mobile phones are ubiquitous around the world and they are the most mobile of all mobile technologies, mobile phone-based data is perceived to be a promising means of cost-effectively assessing human mobility.
There are several possibilities for implementing mobile phone-based data. One option is to apply a handset-based passive mobile phone positioning approach while analysing call detail records (CDR) of mobile phones, as I did in my thesis. This approach provides a vast amount of anonymous data for unique locations of mobile phones in space and time. Namely, CDR data are the log files of the network operator that automatically record information on all outgoing call activities conducted by mobile phone users in the network. This data enables inclusion of potentially all mobile phone users and examination of their spatial mobility, from one day up to months and years within a whole country, and even the entire world when including roaming data from abroad.
One of the most sensitive issues brought up with the use of CDR data is the concern about privacy, ethics, and surveillance fears. However, while exploring the CDR data, there is no fear of violating anyone’s privacy, given that data is encrypted to preserve anonymity and that data reception and handling is strictly regulated by European Union legislation. Furthermore, the spatial positioning accuracy is only up to a city block. In that sense, one should feel comfortable in terms of surveillance fear.
Instead, one should be concerned more about privacy regarding possible leakage of the contents of social networks such as Facebook or blogs, as well as search engines like Google, that record your search requests, browsing, and download history on the Internet.
In conclusion, my thesis is only one step in developing personal spatial mobility research, yet the proposed methodology and empirical findings provide a fruitful premise for future research. It can be estimated that mobile phone-based data, along other ICT-based sensor technologies, will be the basis for management of decision support in operating and planning sustainable ‘smart’ societies in the near future.
