  Flextime is one of the efficient approaches in travel demand management to
reduce peak hour congestion and encourage social distancing in epidemic
prevention. Previous literature has developed bi-level models of the work
starting time choice considering both labor output and urban mobility. Yet,
most analytical studies assume the single trip purpose in peak hours (to work)
only and do not consider the household travels (daycare drop-off/pick-up). In
fact, as one of the main reasons to adopt flextime, household travel plays an
influential role in travelers' decision making on work schedule selection. On
this account, we incorporate household travels into the work starting time
choice model in this study. Both short-run travel behaviours and long-run work
start time selection of heterogenous commuters are examined under agglomeration
economies. If flextime is not flexible enough, commuters tend to agglomerate in
work schedule choice at long-run equilibrium. Further, we analyze optimal
schedule choices with two system performance indicators. For total commuting
cost, it is found that the rigid school schedule for households may impede the
benefits of flextime in commuting cost saving. In terms of total net benefit,
while work schedule agglomeration of all commuters leads to the maximum in some
cases, the polarized agglomeration of the two heterogenous groups can never
achieve the optimum.
