Warning signs

This Technical Measure Document refers to issues surrounding physical and electronic warning signs and how they can be used to minimise the foreseeable risks of a major accident and hazard.

The relevant Level 2 Criterion is

General principles

"For warning signs and alarm indications, the first requirement is to alert the operator to the situation, and then to aid his/her accurate and prompt diagnosis". Ball, P.W.

The following aspects should be considered with respect to Warning Signs:

General issues

Visual warning signs

For Non VDU applications use this table:

Viewing distance (mm) Height in mm
501-900 5
901-1800 9
1801-3600 18
3601-6000 30

Or if the viewing distance exceeds in 6000 mm use the formula: Height in mm = Viewing distance in mm/200

For VDU applications use the following table:

Viewing distance (mm) Height in mm
500 3
700 4.3
1000 4.8

The preferred colour contrasts on VDUs are presented in the table below:

Character Background
Black White
Yellow Dark Blue
White Green
Black Light Grey
White Dark Grey
White Red

Non-Verbal Auditory warnings

Verbal Auditory warnings

Consider using verbal auditory warnings in combination with visual warnings. Use of both methods has been found to improve compliance with the warning message.

Verbal warnings can be more effective in crowd situations when signs can become obscured.

Major hazards

The safety report should address the following points:

Codes of Practice relating to warning signs

The following HSE publications can be used as guidance material relating to safety issues surrounding warning signs:

Further reading material

Judy Edworthy and Austin Adams, 'Warning Signs: A Research Prospective', Published by Taylor and Francis, 1996.

This publication highlights the human behaviour towards the perception of warning signs and the importance of their design, appearance, visibility and recognition.

Case Studies illustrating the importance of warning signs