Since the GPS trajectories are recorded at regular intervals of
one second, the duration of each missing data portion can be readily
calculated. If the duration of a missing data portion is less than
ten seconds, the missing portion is compensated automatically
using a straight line, with lost track points located uniformly on
the line. Otherwise, we ask respondents to provide information
on their travel routes where the track data is missing during the
prompted recall survey. According to the experience accumulated
in the survey, ten seconds is an appropriate threshold which balances
the respondent burdens and accuracy requirements for GPS
trajectories. In total, 4685 segments were extracted from the