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Often at my job when someone is becoming a single source of knowledge or otherwise has a skill that no one else on the team or the department has, a common expression is:

If John was hit by a bus, there would be no one that knows enough about what he does to take over.

I don't believe that this phrase is specific to my job as this also seems to be a common phrase in articles I have read online, for example:


My question, what is the origin of this phrase and is there any reason that it is phrased like "hit by a bus" instead of "in a plane crash" or something else entirely?

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I've learned about it as the "truck factor" and I suspect that the phrase been coined in some book about project management (possibly about software project management specifically, but I'm not sure). – Joachim Sauer Oct 12 '11 at 14:51
In my last workplace it was also referred to as "The Bus Test" as in "If John fails the bus test..." – Waggers Oct 12 '11 at 15:13
I've also heard "the bus factor" - eg "this project has a bus factor of 1", if it depends on one particular person not being sick. – Daniel Roseman Oct 12 '11 at 16:08
It is more familiar to me as "knocked down by a bus" (as in the Conrad story people have quoted, or "goes under a bus". – Colin Fine Oct 12 '11 at 16:09
up vote 11 down vote accepted

People will use "heart attack", "plane crash", "fall off a cliff" as ways to describe that death might happen instantly, and the people left behind better be prepared in case that day happens.

This article talks about it: The Explainer Gets Hit by a Bus

Probably in the mid-20th century. The earliest instance the Explainer could find of a bus accident as a generic rather than literal example of misfortune is from Joseph Conrad's 1907 novel, The Secret Agent: "But just try to understand that it was a pure accident; as much an accident as if he had been run over by a 'bus while crossing the street."

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To address "why a bus and not a plane" part of your question: most people have many more opportunities to be hit by a bus than to be in a plane crash, so "hit by a bus" implies a greater chance that this could actually happen (so you should plan for the possibility).

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The phrase dates from at least 1907 - Joseph Conrad's novel, The Secret Agent: "as much an accident as if he had been run over by a 'bus while crossing the street."

In 1907 you were unlikely to die in a plane crash!

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were planes safer back then? :P – Jordaan Mylonas Oct 13 '11 at 6:02
@Jordaan - much safer, you never see a movie about one hitting an iceberg! – mgb Oct 13 '11 at 16:18
Except for when the Taliban called for a jihad on ice. And that's how global warming started. – Jordaan Mylonas Oct 13 '11 at 22:01

My colleagues these days prefer to use "hit by a lottery" as it's a more pleasant prospect for the one we might lose. (We still say "high bus factor" though, perhaps because it doesn't name names the way "what if Jeremy gets hit by a bus?" does.)

As for the prevalence of the phrase, a year or so ago a colleague of someone close to me was hit by the proverbial bus, and was killed instantly. There was indeeed a great disruption in her workplace. I think it's still a fairly common thing to happen. I don't know anyone (even indirectly) who was in a plane crash or who fell off a cliff. I know many people who were in car accidents, but most car accidents are not fatal.

The thing about "hit by a bus" is that it's sudden, possibly unpreventable (compared to say, having a heart attack), no warning signs (compared to deciding to work somewhere else) and complete. The employee is utterly lost to you without warning. But if you find it a little creepy, let me recommend "hit by a lottery" - it gets a smile every time.

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I also prefer "winning the lottery" to getting "hit by a bus" for precisely the same reason (the more positive connotations). For extra smiles, add on "and sailing on a yacht." :-) – Mike Zavarello May 13 at 11:18

You know, Antoni Gaudí was hit by a tram and died in 1926. It left his work on the church Sagrada Família incomplete. So here is a literal rather than figurative instance.

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