The Impact of Employment Self-Sufficiency Measures on Commuting Time: Case Study of Perth, Australia

The level of commuting in cities is an important indicator of the efficiency of urban spatial structure. Recent research has come out in support of land use policies that promote balancing the number of employment opportunities and residents in local geographical units to reduce excess commuting. This study explores three employment self-sufficiency indices: job-worker balance (JWB), employment self-sufficiency (ESS) and employment self-containment (ESC), as measures for reducing the level of commuting. Using the case of Perth, Western Australia, we perform a trip-based evaluation of these three variables and investigate their effect on commuting time through statistical correlation. The results reveal that JWB, ESS and ESC levels are relatively poor across the metropolitan region. Higher ESS correlates with lower inflow travel time, but better JWB and higher ESC do not necessarily lead to shorter travel times. The findings of this study suggest that policies solely relying on these measures may not be effective in reducing commuting times. ESS and ESC do not account for the component of the trip outside the zone, which can misrepresent the level of commuting in an area. Incorporating travel time in these measures can complement their reliability, and better represent overall commuting levels within an urban structure.