When I defend this thesis I will be 2 months short of 10 years as a PhD student. I've been a PhD student for more than 1/4 of my life (28% to be exact), and there are so many people I want to thank. Fitting 10 years of "thank you":s into one page two pages proved hard, and there are definitely more people I want to thank than there are names in this acknowledgements section. In fact, chances are that if you're reading this, then I want to thank you. So, whatever you've done for me (which includes reading this thesis) -Thank you! Okay. So. 10 years. It is a long time. We've better get started, and what better place to start than at the beginning?Mamma och pappa -thank you for everything! I really do appreciate the good food, long walks and lazy at-home nights, but even more important than good food (weird eh?) has been your non-stop support over the years. Thanks to pappa for discussing maths and physics with me from a young age (I aint scared of no theoretical discussions!), and thanks to mamma for occasionally forcing me to do something other than work. And thanks for letting me live with you when covid hit! I am quite convinced that my living with you guys is the main reasons this thesis is finally done. Erik -thank you for being a great big little brother and for providing me with some much needed non-academic perspectives on life.Pernilla and Camilla (my best friends in primary and secondary school)thank you for your friendship and stability during a time that other... euhm... school-focussed (?)... people often find hard (i.e. högstadiet). Thanks for the afternoon hang-outs and masquerade birthday parties and general silliness! And Emelie, Katharina and Christina (high school friends) -my oh-so intelligent friends that could definitely run the world. Thank you for all week-end trips, insights, and for letting me play with your amazing kids! And Emelie, there will be nice and non-scary crocodiles :-D.Malin -my Maths HL teacher who was super cool and expected us all to do something using mathemathics. Look Malin, I did! Thank you to RISE for the support during the writing of this thesis, and to all the RISE-people! Aronsson -who employed me, taught me almost everything I know about railways, and is the only one of my supervisors who vii