Understanding senior's daily mobility patterns in California using human mobility motifs

Population ageing has been a thorny issue in many countries. One of the challenges is how to improve and change transportation design and transport policy development to adapt to the dramatic changes in the composition of our population. In this paper, we apply a network-based approach of human mobility measurement called “motif” to investigate the distinct patterns in daily travel for seniors (age 60 and above) in California using the 2017 National Household Travel Survey (California-NHTS) data. Motifs are networks of distinct locations visited in a day and the directional movements between them. Using patterns of motifs, we correlate the diverse daily mobility patterns with socio-demographic characteristics as well as built environment factors. We find that 15 distinct motifs can capture approximately 82% and 86% of the total senior respondents on workdays and non-workdays, respectively. Seniors are more likely to have simple motifs with three or fewer distinct locations on non-workdays, while they present more complex motifs during workdays. Given 65% of the included seniors are retired, a large number of seniors present diverse and complex daily mobility patterns instead of staying at home all day. In addition, given the similarity between the urban core, urban district, and urban neighborhood in function and spatial proximity, there is significant heterogeneity in the daily mobility patterns among seniors living in these areas. Furthermore, we find that seniors living in areas with higher percentages of single-family housing units are most likely to stay at home on workdays.