In home health care (our motivating application), consistency is representative of the general health care principle of continuity of care, which is often correlated with quality of care. Much of the existing research involving consistency in routing uses planning horizons that are a week or shorter. Yet in many settings the relationship between an organization and its customers lasts much longer. Hence, this paper looks at how one should plan when seeking consistency in routes extends the impact of caregiver-patient assignments. Specifically, the paper examines appropriate planning horizon length and, with an extensive computational study, demonstrates that a long planning horizon can have significant potential for savings in terms of transportation costs and staffing levels. Initially, a deterministic setting is considered, with all patient requests during the planning horizon known a priori, and the routing cost of planning for two to three months is compared with the cost when planning is done on a weekly basis. With uncertainty inherent in planning for such a long time horizon, a methodology is presented that anticipates future patient requests that are unknown at the time of planning. Computational evidence shows that its use is superior to planning on a weekly, rolling horizon basis.
