Engineer's Puzzle

The Puzzle: The train problem

The brain teaser that's impossibe to solve The Logic quiz for engineers gives the brain strain
Colin, an engineering manager at a component factory in Leeds, is on his way to go and see a customer ‘dahn sarf’ to try and build an ongoing partnership. Staring out the window he begins to wonder, when suddenly whoosh! Darkness descends as the train enters a tunnel... seconds pass as his eyes adjust and his ears pop. ‘How long will this last?’ He thought. And this got Colin thinking.

He gets out his phone and connects to the onboard wifi. He Googles the train type and finds it is 275 yards long. Another quick Google and he converts the figure to an SI unit. By this time he is out the tunnel so he opens up his maps app and GPS, and finds the name of the tunnel he just travelled through. He Googles that too, and finds it is one and a half miles long and it has a speed limit of 50mph.

He can now figure out what he initially wondered: ‘how many seconds elapse between the moment the front of the train enters the tunnel, to the moment the end of the train clears the tunnel?’


Justin Cunningham

This material is protected by MA Business copyright
See Terms and Conditions.
One-off usage is permitted but bulk copying is not.
For multiple copies contact the sales team.

Engineer's Puzzle Entries




Your comments/feedback may be edited prior to publishing. Not all entries will be published.
Please view our Terms and Conditions before leaving a comment.

© MA Business Ltd (a Mark Allen Group Company) 2021