Electrical equipment costs have risen dramatically in the past years: more and more complex systems are being used in tunnels.

Knowing life cycles of equipment helps to reduce maintenance costs and to improve safety.

This report presents the results of an international survey (twenty-seven answers from ten countries) on how tunnel owners behave regarding system maintenance and component replacement. It provide information on average lifetime of the main systems and equipment.

The report reviews the main factors influencing the ageing process. It presents recommendations for the use of cost cycle analyses in relation to the strategies for selection and maintenance of tunnel equipment.