Staff scheduling at the United States Postal Service

The purpose of this paper is to present a full-scale model of the tour scheduling problem as it arises in the United States Postal Service, and to examine several scenarios aimed at reducing the size of the workforce. The problem is formulated as a pure integer linear program and solved with CPLEX. The baseline model includes both full-time and part-time workers, as well as the principal constraints defined by the union contract. The scenarios include requirements for two days off in a row, variable daily start times, the use of part-time flexible workers, and a parametric analysis of full-time to part-time restrictions. The results indicate that problem instances of realistic size can be solved within 1 h, and that measurable savings can be achieved by departing from current practice.

[1]  Andrew J. Mason,et al.  Integrated Simulation, Heuristic and Optimisation Approaches to Staff Scheduling , 1998, Oper. Res..

[2]  Larry W. Jacobs,et al.  Optimal Models for Meal-Break and Start-Time Flexibility in Continuous Tour Scheduling , 2000 .

[3]  Christine Strauss,et al.  An enhanced rostering model for airline crews , 2001, Comput. Oper. Res..

[4]  Nicholas Beaumont.  Using mixed integer programming to design employee rosters , 1997 .

[5]  Hesham K. Alfares.  An efficient two-phase algorithm for cyclic days-off scheduling , 1998, Comput. Oper. Res..

[6]  Michael J. Brusco,et al.  Personnel Tour Scheduling When Starting-Time Restrictions Are Present , 1998 .

[7]  Michael W. Carter,et al.  Work Force Size and Single Shift Schedules with Variable Demands , 1985 .

[8]  M. Brusco.  Solving personnel tour scheduling problems using the dual all-integer cutting plane , 1998 .

[9]  S. L. Hung,et al.  Development of a workforce management system for a customer hotline service , 2000, Comput. Oper. Res..

[10]  Hamilton Emmons.  Work-Force Scheduling with Cyclic Requirements and Constraints on Days Off, Weekends Off, and Work Stretch , 1985 .

[11]  Stephen E. Bechtold,et al.  Implicit modeling of flexible break assignments in optimal shift scheduling , 1990 .

[12]  James E. Bailey,et al.  Integrated days off and shift personnel scheduling , 1985 .

[13]  George B. Dantzig,et al.  Letter to the Editor - A Comment on Edie's "Traffic Delays at Toll Booths" , 1954, Oper. Res..

[14]  M. Segal,et al.  The Operator-Scheduling Problem: A Network-Flow Approach , 1974, Oper. Res..

[15]  Kenneth R. Baker,et al.  Workforce Allocation in Cyclical Scheduling Problems: A Survey , 1976 .

[16]  Manoj K. Malhotra,et al.  A model for scheduling postal distribution employees , 1992 .

[17]  Jonathan F. Bard,et al.  Solving large-scale tour scheduling problems , 1994 .

[18]  R. Tibrewala,et al.  Optimal Scheduiing of Two Consecutive Idle Periods , 1972 .

[19]  Nicholas Beaumont,et al.  Scheduling staff using mixed integer programming , 1997 .

[20]  T. Aykin.  Optimal Shift Scheduling with Multiple Break Windows , 1996 .

[21]  James B. Orlin,et al.  Cyclic Scheduling via Integer Programs with Circular Ones , 1980, Oper. Res..