Sisyphus was a character of Greek mythology who, for his misdeeds, was condemned to roll a stone up a hill, only to see it roll back down and start over again. The legend offers several analogies to introduce key concepts in transportation: volume, distance, friction, and effort.
- Volume. Represents a number of passengers or freight that can be carried as a single load.
- Friction. The difficulty of moving a volume per unit of distance is often referred to as the friction of distance. For instance, it can be related to the quality of transport infrastructure, including capacity and maintenance.
- Effort. The amount of energy required to move a volume per unit of distance, considering the friction. It is commonly represented as the transport cost. Essentially, Effort = f(volume, distance, friction).
If friction were reduced (lower angle on the above figure), it would require less effort to move the same volume over the same distance. Consequently, a core goal of transportation is to reduce the friction of distance, mostly through infrastructure, capacity, and technological improvements.
Another element of the myth is its repetitiveness, which also applies to transportation. Commuting is an activity that must be repeated constantly, as the effort spent on one commute cannot be transferred to another. The same applies to supplying goods to the market, a process that must be repeated continuously since current transportation efforts cannot be substituted for past efforts.