Technical requirements for organising successful mobility campaigns in citizen observatories

Traditional travel surveys are usually organised in a top-down manner, when data collection is commissioned by transport authorities. Recently, however, there has been an increasing tendency towards bottom-up initiatives when citizens and stakeholders initiate and implement data collection campaigns in citizen observatories. Citizen observatories are usually based on participatory sensing, i.e. data collection by volunteers using smart mobile devices. The ubiquity of smartphones and hardware developments make it a potentially useful instrument to have travel behaviour registered. However, creating a new citizen observatory remains technically difficult and labour-intensive. Today, citizen observatories have to be developed from scratch, which acts as a significant barrier to their implementation. Recently, an open, reusable and reconfigurable citizen observatory platform has been proposed. Through such a platform, ICT-agnostic stakeholders are able to initiate new citizen observatories in various domains. In this paper we have developed a general technical framework for a platform that can allow stakeholders to create citizen observatories, with the aim of collecting data on travel behaviour. The framework is based on the functionalities of travel survey applications, elaborating on the potential limitations and enhancements of a citizen observatory platform compared to travel survey apps. First, we compared the functionalities of smartphone-based travel surveys and citizen observatories, which exposed the main areas of concern of citizen observatories compared to traditional travel surveys. Next, we developed a framework for the technical requirements to organise a citizen observatory for mobility. The three main stages in this framework are the collection of raw data, processing it into valuable behavioural and environmental information (e.g. travel modes, air pollution) and the feedback of this data to all stakeholders. Data validation should be applied in each stage and it is important to ensure user acceptance during the entire lifespan of the campaign. We highlighted points for attention that should be considered when developing a citizen observatory for mobility. Defining the required accuracy, representativeness and reliability in a specific campaign are key questions in the context of an acceptable rate of battery drain. The technical requirements developed in this paper reflect a 'best-case scenario' that will later be tested with specific use cases.