Things that have never happened before happen all the time.

Scott D Sagan The Limits of Safety

Spad situation

Drive a mile in my seat: signal design from a systems perspective.

A paper by Dr Anjum Naweed and John Aitken.

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You can get lonely out there!

Keeping in communication with people who are in isolated locations.  A paper by John Aitken.

Red and green buttons


A paper by presented to the International Railway Safety Council.



Enhancing error tolerance, error detection and error recovery to together produce system safety.


Aitken & Partners takes a very broad view of safety; we consider equipment and technical systems in their human environment. This is often described as Functional Safety, although that term is often more limited in its application. Few, if any, organisations are capable of fully addressing all the considerations for functional safety. Our expertise is in the electrical area, particularly in the railway environment. We have particular skills in electromagnetic compatibility, communication systems, locomotives and signalling systems.

"Safety is not the absence of failures. Safety is the presence of defenses." Todd Conklin


Things that go Wrong

Sometimes things do not work as expected. The consequences are often tragic and affect many people directly and indirectly. The railway industry, like many others, seeks to learn from each time that something has gone wrong. Accident investigation reports are made available by many railway investigators and contain very useful analysis of incidents. At Aitken & Partners we study these reports, seeking to increase our understanding and the resilience of systems used by our clients. Some of our findings are in our technical papers, which you are welcome to download.


Engineering systems have long relied on redundancy and diversity to achieve high levels of reliability.  The effects of each of these techniques can be modelled mathematically and their cost-effectiveness can be evaluated. 

Resilience extends these concepts, taking into account the system in its environment, its interaction with its users and with other systems.  It involves enhancing error tolerance, error detection and error recovery together to produce system safety. 

These concepts are discussed in some extracts from books and journals in Resilience Engineering.

Things that go Right

When we think about safety, we often focus on failures.  Perhaps that is because we see safety as a a description for the abscence of harm, rather than the embodiment of success.  Thorough engineering design, taking time to fully understand the environment and the system are mechanisms to ensure success.  They are often called "good engineering practice" but there is more to it than that.  Experience and insight play a significant part; so does willingness to look across disciplines; enthusiasm to understand the underlying principles and commitment to learning more about each aspect of a system.  We work with experienced colleagues from many disciplines to ensure that our understanding is broad and based on substance.

"The enemy of safety is complexity."

 Behind Human Error, Woods et al, Ashgate 2010 p 23

"Knowledge and error flow from the same mental sources, only success can tell one from another."


Ernst Mach, 1905