Essays on Staffing and Transportation

On Monday 27 May 2024 Christian Braathen will hold a trial lecture on a prescribed topic and defend his thesis for the PhD degree at NHH.

Why?

That is the guiding phrase when developing mathematical programming models. Not only to develop insights and understand why the problem is what it is, but also to know why we are interested in the problem in the first place.

A major reason mathematical programming models are worthwhile developing is because they have the potential to improve people’s lives directly and indirectly. As a colossal number of people spend substantial parts of their day either working or commuting, even incremental improvements in their work life or commuting experience can significantly impact society. Hence, it is interesting to pursue problems of staffing and transportation. And Christian Braathen's thesis is driven by that why.

Chapter 1 is a resource allocation problem and schedules mass interviews in a volunteer-driven organization. As volunteerism is a substantial cogwheel in modern-day societies, and since the volunteers do not receive a salary for their efforts, it is imperative to delegate tasks and responsibilities they prefer to remain motivated. In the context of mass interviews, it is important to ensure the volunteering interviewers receive favorable meeting schedules.

Chapter 2 is a logistics problem and studies how social constraints—and overtime considerations in particular—affect the selected routes and the quality of the solution. While the vehicle routing problem (VRP) has been thoroughly studied, a large share of studies ignores social constraints despite their importance. The chapter shows that cost savings and social constraints are not necessarily trade-offs, as the former was achieved while respecting the latter.

Chapter 3 is a public transportation problem and studies the operational implications and benefits for passengers when ferries are operated autonomously instead of manually. Due to potential practical limitations in the number of operating hours for autonomous ferries and due to other transportation alternatives, that will operate the most during high-demand hours, this chapter suggests that autonomous ferries may provide significant value when used in combination with other transportation alternatives if used during low-demand hours of the day—from late evenings to early mornings in addition to weekends.

Chapter 4 is concerned with privacy issues that can arise from suppressed data points. The chapter studies a synthetic data set on commuting that has suppressed data points when the number of commuters from one location to another is low. The chapter demonstrates that suppressing the information in cells with a low number of observations does not necessarily preserve privacy adequately, and the chapter presents approaches to improve privacy preservation. Additionally, the chapter recommends that researchers develop sound methods to adjust for suppressed information rather than just ignoring the cells by setting the values equal to zero.