Job accessibility and commuting travel: A spatio-temporal analysis and a case study in Hong Kong

Abstract

The role of jobs-housing balance in reducing commuting distance and time has been widely discussed in sustainable transport and land-use planning. To date, smart city development featured by information and communication technology (ICT) has offered researchers massive and reliable data to understand urban mobility and travel behaviour. Recent literature which applies big data to analyse jobs-housing balance, has largely matched the previous findings that a better jobs-housing balance can encourage self-containment and reduce travel. Apart from using ICT-related infrastructure to facilitate transport research, future transport planning should also conform to the ‘smart principles’ in mobility planning and city development. A smart city should be supported by innovative strategies that embraces sustainable development (United Nations, 2015), and promotes smart mobility by decarbonising the transport sector in the long-run (European Commission, 2017). In light of this, this paper attempts to offer ‘smart strategies’ to decarbonising transport system through enhancing job accessibility in communities. This paper aims at achieving two objectives. First, it relates job accessibility to commuting behaviour in a community. In most literature, the ratio of jobs to total population or active labour is applied to indicate jobs-housing balance. However, the proportion of jobs to total population might not be the only factor that affects commuting pattern. For example, only increasing employment in a community might not be necessarily effective. Instead, the nature of jobs, density of employment and relative competition are all relevant parameters that would affect the overall commuting behaviour and residence locations. Second, it analyses working trips using a time-geographic approach. Time geography integrates spatial and temporal components that demonstrate individual travel and activity patterns in society. In relation, this paper develops a spatio-temporal framework to quantify travel behaviour. Secondary data of the Travel Characteristics Survey 2011 (TCS 2011), a wide-territory and comprehensive questionnaire conducted every 10 years by the Transport Department, HKSAR, will be utilised in the study. All commuting journeys made by full-time and part-time workers on a referenced weekday will be extracted for analysis. The primary hypothesis is that increasing job accessibility can reduce commuting travel. In this paper, it is proposed that job accessibility can be affected by (i) density of employment opportunities, (ii) diversity of jobs and (iii) number of jobs available relative to the total population. Moreover, job accessibility is calculated based on the tertiary planning units (TPUs) as defined by the Census and Statistics Department. This helps illustrate how job accessibility varies in different communities and affect the commuting behaviour in Hong Kong. To illustrate the commuting patterns, this research introduces the concept of space-time prisms (STPs) to synthesise space (i.e. travel route) and time (i.e. journey time) of travel. A three-dimensional STP, which captures the volume of a two-dimensional space and a one-dimensional time, can depict the spatio-temporal components of commuting in one analytical framework. The larger the STP, the higher amount the travel (in space and time) is, or vice versa. Overall, it is anticipated that an increase of job accessibility can reduce the STP of commuting in a neighbourhood. This can shed insights on the formulation of transport and land-use strategies in the future smart city. With the growing amount of precise spatio-temporal data, it is believed that the spatio-temporal framework here can benefit the future analysis of travel behaviour.