“…Overall, there are many options to model shipment size in the empirical literature. Some authors consider shipment size as a continuous variable (Sakai et al, 2020;Koning et al, 2018;Abate and de Jong, 2014;Combes, 2009;Holguín-Veras, 2002;Abdelwahab and Sargious, 1992), others as discrete (Keya et al, 2019;Abate et al, 2019;Piendl et al, 2017;Pourabdollahi et al, 2013;Windisch et al, 2010;de Jong and Ben-Akiva, 2007). Some articles assume shipment size is unaffected by mode choice (Sakai et al, 2020;Kawamura et al, 2010;Wisetjindawat et al, 2005) or conditional on it (mode-specific influences are included as binary indicators (Combes, 2012)), whereas others account for the interdependencies between decisions, either implicitly or explicitly (Keya et al, 2019;Abate et al, 2019;Irannezhad et al, 2017;Combes and Tavasszy, 2016;Abate and de Jong, 2014;Pourabdollahi et al, 2013).…”