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Computer-aided Organisation of the Working Time with the Help of BASS

Simple and practical: this is how you optimise your working time system

BASS is a software allowing for designing and evaluating simple to highly complex working time systems. In addition to the statutory and tariff conditions, the program also takes into consideration stress situations and economic aspects, as well as recommendations for the organisation of the working time.

BASS Workflow

The requirements for new and innovative forms of the organisation of working time are manifold: along with industrial safety and health, economic interests must be safeguarded as well, such as the maintenance or increase of the competitiveness.

Frequently, the question regarding the "best" shift or working time system is asked. However, there are no easy answers, since companies work with different employees, in different regions, with different technologies, and under different conditions. Yet, working time systems may be tailored to the individual requirements of companies and employees.

The BASS software developed by the Federal Institute for Occupational Safety and Health (BAuA) supports companies in representing, evaluating, and optimising working time systems. It is intended to particularly support small- and medium-sized companies in implementing the statutory provisions and the ergonomic recommendations regarding the design of working time systems.

Examples for working time systems created using BASS

Below, we present three working time systems that were developed and evaluated with BASS, respectively. A short description of the initial situation is, in each case, followed by a representation of one or several alternatives of working time models evaluated according to statutory provisions and ergonomic recommendations.

Discontinuous 7-week system

In a medium-sized company of the processing industry with about 260 employees, the work has been performed using a discontinuous 3 shift system for three shift work forces from Monday to Friday (15 shifts/week) up to now, with weekly forward rotating shifts.

The average weekly working time was 40.0 hours/week. Due to the good order situation, the hours of operation are to be expanded to up to 17 shifts/week. The introduction of a morning shift on Saturdays and a night shift on Sundays results in a shift system with 45.33 hours/week and significant stress due to the increased weekly working time, first and foremost due to six consecutive night shifts, as well as the allocation of working time to all weekends.

The question was: Considering health and social aspects, how can a discontinuous shift systems with 17 shifts/week be designed?

A 7-week system with hours of operation from Sunday 10 pm to Saturday 2 pm is an alternative taking into consideration the conditions in the company, the Working Time Act, and the ergonomic recommendations. For this purpose, each of the three existing shift work forces is divided so that six groups are created. Additionally, a 7th shift work force is introduced comprising 1/6th of the previously existing work force, i.e. half of a shift work force. Two of these new shift work forces work together in one shift in each case, but in a different composition.


  • Continuous weekly rest period in week 1 and week 5 too short (32 hours) Compensation: within a fortnight –this is OK according to the law, but disadvantageous from an ergonomics point of view.
  • 4 disadvantageous shift sequences NIGHT-off-MORNING within seven weeks


  • 3 consecutive night shifts at most
  • 3 complete weekends off in 7 weeks
  • 2 consecutive late shifts at most
  • Short rotation
  • Forwards rotation
  • 5 consecutive working days at most

Even when changing the shift sequence in the represented 7-week system, an ergonomically more advantageous alternative is hardly possible: avoiding the disadvantageous shift sequences NIGHT-off-MORNING, for example, may result in a partial backward rotation, a reduction of the weekends that are completely off, or long late shifts. This way, one disadvantage is replaced by another or several other disadvantages.

This shows that the margin for designing discontinuous shift systems with more than 16 shifts/week is limited in accordance with the ergonomic recommendations. Therefore, it makes sense in any case to consider a transit to continuous shift systems in the event of such an expansion of the hours of operation.

Continuous 3-shift system with different personnel requirements

In the field of nursing and geriatric care, continuous night shifts are still often daily fare. In a geriatric care facility with a total of 85 employees, a possibility to eliminate this arrangement by integrating the night shifts into the day shifts was sought. In particular, possible solutions must take the differing personnel requirements during the days and the week into consideration.

With the help of the BASS program, different personnel requirements can be entered, corresponding shift times can be created, and the sequence of the shifts can be organised.

Step 1 - input of the requirements in BASS:
Initially, the number of carers required in each case at certain times of a day and for every day of the week is input into the BASS program. From Monday to Friday, one carer is required between midnight and 6 am, three carers are required between 6 am and 12:45, and five are required from 12:45 to 2:15 pm. On the contrary, less personnel is scheduled during the day on the weekend – i.e. two carers from 6 am to 12:45 and four carers from 12:45 to 2:15 pm.

Step 2 - generation of the shifts:
On the basis of these personnel requirements, BASS calculates the corresponding shifts including the start and end times, as well as the respective personnel requirements in the shifts. The morning shifts from Monday to Friday include more personnel than the late shifts, but at the weekends the personnel requirements are the same. The night shift includes one employee for all days.

Step 3 - creating the work schedule (shift sequence):
BASS creates a duty roster with a cycle of 9 weeks for an intended average weekly working time of 38.5 hours. The shift sequence was optimised manually afterwards. The compensation between the weekly working time of the 9-week system of 37.83 hours and the agreed upon weekly working time of 38.5 hours is achieved via occasional substitution in the event of illness and leave.


  • 7 consecutive late/night shifts
  • Always 7 consecutive working days
  • Long night shift (9 hours + 45 minutes break)


  • 4 consecutive night shifts at most
  • 4 consecutive late shifts at most
  • At least 4 days off after night shifts
  • 4 complete weekends off in 9 weeks, distributed relatively consistently

The schedule shows a strong concentration of working days which is not recommendable from an ergonomic point of view. However, the plan was acceptable for the carers exactly for this reason, since the change of shift also occurred every 7 days up to this point in time.

Discontinuous 2-shift systems without night shift

In discontinuous 2-shift systems without night shift, the hours of operation are distributed between the early morning and the late evening, mostly covering 5 days during the week from Monday to Friday. In a storage and service company with about 300 employees where the work was performed from Monday to Friday in morning and late shifts in each case, shortened delivery periods prompted the question of how the hours of operation can be expanded to Saturdays – maintaining the agreed upon five-day week for the employees.

Since the shift work forces were relatively large, it was possible to form 6 groups with a rolling day off during the week in each case intended to compensate for the additional working hours on Saturdays. The cycle time is twelve weeks with the morning and late shifts changing on a weekly basis. A 5-day week can be maintained for the individual employee.

Upon consultation with the employees, a shift schedule was developed including the additional morning shift on the Saturday of the late shift week. This met the desire of the employees regarding longer periods of spare time at the weekends. In order to guarantee the statutory period of rest of eleven hours between late and morning shifts, the late shift ends earlier on Friday and the morning shift on Saturday starts later than on the other days. Through this adaptation of the times for the change of shift, the statutory provision was met, but the resulting backwards rotation of the shift is not recommendable from an ergonomic point of view. As a consequence, compliance with the period of rest should be made sure given the timewise tight change from late to morning shift.


  • Backwards rotation from late to morning shift
  • Individually dispersed days off in the 3rd, 4th, 7th, and 10th week
  • Morning shift starts at 5:30 am


  • Every 2nd weekend is a long weekend (morning shift week)
  • Readily comprehensible for company and employees
  • 5 consecutive late shifts only once

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Working Time Box

Simple practical help for the organisation of working time

Find out more : Working Time Box …


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