Bus factor

Personnel must be both key and irreplaceable to contribute to the bus factor; losing a replaceable or non-key person would not result in a bus-factor effect.

The expression "hit by a bus" describes a person either dying or more generally disappearing suddenly from the project.

For instance, say a team of 30 people produces bread in three necessary steps: mixing ingredients, kneading the dough, and baking.

An early instance of this sort of query was when Michael McLay publicly asked, in 1994, what would happen to the Python language if Guido van Rossum were to be hit by a bus.

[citation needed] In many software development projects, one goal is to share information in order to improve the bus factor, potentially to the size of the entire team.