LECTURE - 3 RESOURCE AND WORKFORCE SCHEDULING IN SERVICES Learning objective To explain various work shift scheduling methods for service sector.
8.9 Workforce Management Workforce management deals in the process of balancing the allocated work by the available resources to complete the work. Generally, service organizations face varying demand, which is very difficult to manage with demand management strategies (discussed in last module). In such cases workforce scheduling or rostering can be performed to allocate right size of resources against varying demand. Determining right size of resources are always a challenge because hiring or staffing too many people during low demand hours or days of a week may increase cost of operation, whereas hiring or staffing too low number of employees during high demand my impact the service quality or target service levels. Work shift scheduling helps in finding employee shift arrangements to match a time varying demand for a service. 8.9.1 Work shift scheduling Work shift scheduling problems can be seen in assigning postal employees of post offices, nurses in hospitals, pilots or crew staff in airline industry, or police officers to specific workdays and shifts. The scheduling is done when customers demand quick response and total demand can be forecasted with reasonable accuracy. In such cases, capacity is adjusted to meet the expected loads or customer demand on the service system.various elements to be considered in workshift scheduling or the factors which result in different workshift scheduling problems are given below. Demand modeling: determining the number of staff required at each time interval over planning period or rostering horizon. The planning period can be a shift of some number of hours, number of shifts per day or number of shifts per week. Various forecasting tools can be used to predict the demand. Scheduling workforce in time periods or intervals: Service organizations need to schedule workforce daily and/or weekly with consideration of number of days off taken by employees, consecutiveness and non-consecutiveness of number of days off. Similar considerations apply to number of shifts an employee can do, Minimum break between shifts etc.
Cyclic or acyclic rosters: In case of repeating demand patterns, all employees of same class perform same line of work for same length of shift but may be with different starting time of first shift or duty. Such kind of pattern can be seen in transport services like bus and railways. Whereas, in acyclic rosters, the line of work for employees is independent and have different starting time of shift and different length of shifts. Such rosters can be mostly seen in the service sectors having different demand patterns like call centers and Information Technology enabled services. Performance measures: Minimize number of workers required, Cost of operating number of employees, Minimize customer response time, target service level (attending some target percentage of calls in specified time) Regulations: Total working hours, number of shifts per day or per week, number of hours per shift, leave and other contingencies Other constraints: Minimum number of employees desired each period; demand to be met at each time interval, preferences of employees based on qualification and seniority etc. 8.9.2 Work shift applications in different service sectors As mentioned in the above section, that various factors can impact resource or work force scheduling. It further varies form one service sector to other service sector. Some of the special features and challenges faced by different service sectors are given below and briefly described in Table 8.4.
TABLE 8.4: RESOURCES TO BE SCHEDULED IN DIFFERENT SERVICE SECTORS Service Sector Sub sector Resources to be scheduled Important Decisions Transport Airlines Aircraft scheduling and crew scheduling Assign an individual aircraft to flights Assign fleet types to the flight segments Crew (pilots and flight attendants) pairing and crew assignment for predefined flight segments Bus and Railways Drivers and duty staff scheduling, Assigning train types Schedule drivers and duty staff for a given starting location and time and finishing location and time from a pre-defined and fixed Time table Assign type of trains between segments Call centers Workforce scheduling Schedule workforce in highly variable demand with nature and number of tasks unknown a priori Healthcare Doctors and Nurse scheduling Schedule doctors/ nurses based on qualification, number of patients in a ward, type of ward with fair distribution of night and weekend shifts. Emergency services Police and Ambulance Duty employees scheduling Assign right number of employees who can reach within specified time to the emergency incident or taking least response time Hospitality and Tourism Hotels and Restaurants Employee scheduling Schedule employees with different skills like catering, housekeeping, accounting, bookings etc. 24 hours and 7 days. Schedule mix of part time and full time employees to meet fluctuating or seasonal demand over a day or over a season
Transport related service (Airline/ Railways and Bus) Transport related services sector have temporal and spatial feature involved in starting time and location and finishing time and location. There can be many decisions regarding scheduling of resources in airline sector like given below: Assign an individual aircraft to flights. It depends on the demand at flight segment, seating capacity required of airline s fleet and competition in a particular flight segment. Assign fleet type to the flight segment. Flight segments are represented by two nodes that is airports and the arc between two nodes. The first node represents the departure time and origin airport. The second node represents the arrival time and destination airport. This assignment has to include the aircraft maintenance routing problem Crew scheduling which is comprised of crew pairing and crew assignment. In airline sector crew can be pilots and flight attendants. Crew pairing is done for a given set of pre-defined flight segments over a period of time considering crew base and legal crew pairing. Crew base is a base where crew members can start and end with over the time period. Legal crew pairing is a sequence of connected flight segments beginning and ending at a crew base satisfying constraints like governmental and contractual restrictions of maximum daily working hours, minimum overnight rest period, maximum number of flight legs and maximum time away from a crew base. Crew assignment is done thereafter where individual crew is assigned into trips that are sequences of crew pairings over a certain period of time (mostly a month). Bus and railway schedules and rosters are usually constructed as per fixed and given time table. Time scale for bus and railways transport services is generally much smaller as compared to airline sector. In bus transport main decisions required are as given below. Assign buses to depots or lines Number of trips per line Frequency of buses Deadheads in different routes
Number of drivers required in different shifts Rest period of drivers Similar decisions are required for railways where the trip segments are railway stations. Healthcare The main challenge in the healthcare is to provide right amount of care to the patient at right time considering the severity of health related problem utilizing right and qualified workforce considering patient care and safety. The resources to be managed are capacity in terms of number of beds required, scheduling operating and recovery rooms and scheduling doctors and nurses for different wards. Workforce scheduling is done considering following factors. Assign suitable, appropriate and qualified nurses to different medical wards Number of patients in the ward Patient to nurse ratio required Permanent and temporary staff required Fair distribution of night shifts and weekend shifts Call arrivals for inpatients and outpatients Call center In call centers the workforce requirement varies from day to day and from week to week. There is no geographical or spatial feature involved in this sector. Work force requirements pattern can be worked out for entire planning horizon but the exact nature of task, number and sequence of tasks to be performed are not known in advance. The calls have to be assigned to staff based on different call handling skills of the staff. The financial services and Information Technology enabled services also face similar demand trends. Hospitality and Tourism The hospitality and tourism sector faces extremely seasonal demand fluctuations. The other challenge is to manage different specializations like catering, housekeeping, accounting and billing and reservations. Each specialization require different staffing needs. Housekeeping needs are based on the ratio of number of workers and number of guests, time taken to clean the room, timing of cleaning and assign workers to different shifts. Reception has to take
care of the waiting time of guests, skill in managing different needs of the guests. Catering and food are very important to retain a guest or customer. This specialization itself needs various kind of skills like quality food preparation, room delivery, cleaning, knowledge of different tastes of guest etc. Scheduling of workforce from different departments under one roof is a big challenge in hospitality. 8.10 Work shift scheduling with days-off constraints Let s say a service organization need to schedule employees where organization works for seven days a week and provides each employee two consecutive days off. The service organization can be a retail store, hospital, Airline sector and police services. Such services are available 24 hours of the day and 7 days of week round the year. The service organization incurs cost of operation for hiring so many employees. The organization wants to minimize the total number of employees or to minimize the total slack capacity. At the same time based on the predicted demand each day requires minimum number of employees. As per rules, each employee wants two consecutive days off from work not necessarily weekend. In such scenario the problem of service organization is to schedule workforce. Formulation of problem Let s an employee working for particular set of 5 days of week with 2 consecutive days off be called a tour. That means there can be in total 7 tours, where each tour will start on a different day of the week last for 2 consecutive days off followed by 5 working days. Notations i = Tour, where each tour begins with 2 consecutive days off (i=1, 2, 3 7) x i = Number of employees assigned to tour i j = Day of the week (j=1,2, 7) b j = Minimum number of employees desired each day of the week Objective function Minimize x 1 + x 2 + x 3 + x 4 + x 5 + x 6 +x 7
Constraints x 2 + x 3 + x 4 + x 5 + x 6 b 1 (Sunday) + x 3 + x 4 + x 5 + x 6 + x 7 b 2 (Monday) x 1 + x 4 + x 5 + x 6 + x 7 b 3 (Tuesday) x 1 + x 2 + + x 5 + x 6 + x 7 b 4 (Wednesday) x 1 + x 2 + x 3 + x 6 + x 7 b 5 (Thursday) x 1 + x 2 + x 3 + x 4 + x 7 b 6 (Friday) x 1 + x 2 + x 3 + x 4 + x 5 + x 6 b 7 (Saturday) x i 0 and integers The above problem is formulated as Integer Linear Programming model. 8.11 Work shift scheduling over planning period with demand varying in small time intervals Most of the service sectors like call centers and telecommunications face fluctuating and varying demand in the small time intervals over a planning period. It poses challenge to the service sector first to analyze the demand for all time intervals as shown in Figure 8.5, and then allocate the staff to these intervals based on the target service levels and other company related constraints pertaining to rules and regulations.
Demand 5AM 2PM 5A Time FIGURE 8.5: VARYING DEMAND AT DIFFERENT TIME INTERVALS OVER A PLANNING PERIOD To manage such demand the service organizations follows following steps: 8.11.1 Demand forecasting Service organizations first realize the demand in small time intervals. The demand can be number of calls arriving at call center or number of requests of tickets by the customers to software companies. In each time interval, organization notes down the number of arrivals which will help in determining the time required to meet or satisfy the demand and number of employees required on the basis of service target levels. For example, a company receives 20 requests from 6:00AM to 6:30AM with average handling time of 150 seconds. Various forecasting models can be used to forecast the demand over planning period. 8.11.2 Allocation of employees or staffing To schedule the number of employee for each interval it is required to set some service target level which company wants to achieve. The service target level may vary from company to company and form sector to sector. Service target levels can be set as Answer
92% of incoming queries within 20 seconds, answer calls in some interval within an average of 25 seconds, Idle time for any employee should not be more that 20% of the total working time etc. Such service target levels help in assigning the number of employees to meet forecasted demand during some time interval. The demand arriving in some time interval can be considered as a queue. A service company may further face different types of requests which can be considered as different queues. These different requests can be attended by any employee or based on the type of request company has to allocate special skill and/or competency for different requests. For example, the customer may need some technical support which can be answered by technical team of service organization only or it may be some product promotion related query which does not require technical know-how about any service product. So, the allocation of staff depends on the forecasted demand, types of queries or request, number of queues, service level targets and multi-skilled employees required. The best way to solve the problem of staffing in such scenarios is to utilize queuing theory based models or simulation. 8.11.3 Constraints and performance measures to model staffing problem After understanding the type of demand and the way demand arriving at some service organization, we can determine the number of employees required in each time interval. The next information required is about the constraints a company faced while staffing the employees and the performance measures utilized to staff. The constraints can be of the following nature. Number of shifts planned by service organization Allowances provided to the employees for their personal breaks Start and end time of shifts Number of days an employee can take-off Minimum gap between two shifts an employee must consider
Based on the special skill required to meet customer demand an employee or multiple employees are scheduled for specified shift The route to be followed to complete the task. The customer request may require a number of tasks to be performed in sequence by a number of different employees Flexibility given to the employees to choose their shifts The performance measures can be in terms of optimizing number of employees by eliminating under-staffing or over staffing. The service organizations may like to focus on service target levels. The service organizations may like to reduce the cost of operation by hiring mix of full time and part time employees. Based on the performance measure and considering all the constraints, the service organization may adopt iterative procedure to staff employees at different time intervals till they get optimal results. 8.12 Scheduling Part time employees Some of the service organizations experience demand with predictable variations like banks and outpatients visiting specialist doctors. In a week, such services face peak demand on a particular day of the week and drop in demand some other day of the week. If service organization hires number of full time of employees required to meet peak day s demand and retain the same numbers throughout the week, then some of the employees will be idle on other non-peak demand days. The idle time will add cost to the service organizations. In such cases organizations can hire part time employees to satisfy the demand of peak days. The service organizations need to consider the following while scheduling aprt time employees.
To provide equity among part time employees there should be some specified maximum number of hours or number of days for which part time employees can work. To meet the requirements of part time employees with minimum number of part time employees. To employ minimum number of part time employees. Any service organization can follow following steps to schedule part time employees. Let s illustrate with an example. A service organization ABC need to plan and schedule number of part time employees where the total number of employees required each day of the week is presented in Figure 8.6. The manager of ABC has decided to have part time employees where a part time employee will work for at least 2 days but not more than 3 days per week. 8 7 Number of employees 6 5 4 3 2 1 0 Monday Tuesday Wednesday Thursday Friday Days of week FIGURE 8.6: NUMBER OF TOTAL EMPLOYEES REQUIRED OVER A WEEK IN ABC
Step 1: Determine the minimum number of part time employees needed We can see from the Figure 8.6 ABC requires two employees on Wednesday which is the minimum requirement in a week. ABC will plan to have two full time employees. After deciding full time employees, ABC is left with 12 employee days to be covered in a week. Any part time employee can work for maximum of 3 days per week. In a week, ABC requires maximum number of part time employees on Monday that is 5, which determines the feasible minimum number of part time employees required. Step 2: Develop decreasing demand of number of part time employees required histogram After determining the total number of part time employees required, we need to schedule them over a week. Plot a histogram with decreasing demand of number of part time employees over a week as shown in Figure 8.7. 6 Number of part time employees required 5 4 3 2 1 0 Monday Friday Thursday Tuesday Wednesday Days of week with decreasing demand of part time employees FIGURE 8.7: NUMBER OF PART TIME EMPLOYEES REQUIRED WITH DECREASING DEMAND OVER A WEEK
Step 3: Assign part time employees for different days of week Starting with first part time employee, assign him/her to the first block on Monday as shown in Figure 8.8, the second part-time employee to the second block and so on to assign all five part time employees on Monday. Similarly assign part time employees to other days of week. 6 Number of part time employees required 5 4 3 2 1 0 5 4 4 3 3 2 2 1 1 1 5 2 Monday Friday Thursday Tuesday Wednesday Days of week with decreasing demand of part time employees FIGURE 8.8 ASSIGN PART TIME EMPLOYEES IN THE BLOCKS OF EACH DAY OF THE WEEK We can see from Figure 8.8 that employee number 1 and 2 are scheduled for 3 days in a week and employee number 3, 4 and 5 are scheduled for 2 days in a week.