"...speed and rapid change together push towards tightly-coupled systems with dense webs of self-sustaining relations...


...when things go wrong disruption is rapidly and unpredictably transmitted through the system....
And when they fail there is no play.  No slack.  Everything falls down.  The conclusion is that partially connected, multiply ordered, ambiguous and not very coherent systems are usually more robust.

...we have unwisely created a world which demands coherent systems."
Extracts from John Law, 'Ladbroke Grove, or How to Think about Failing Systems' published by the Centre for Science Studies and the Department of Sociology, Lancaster University (version: paddington5.doc, 15th August, 2000) http://www.comp.lancs.ac.uk/sociology/soc055jl.html




SPAD - Signals Passed At Danger, the term used to describe an incident when a train passes without authorisation a signal displaying a danger aspect.