At its meeting in Helsinki in 2011, International Tunnelling Association Working Group 5, identified the need for guidance on the provision of refuge chambers in tunnels under construction. A refuge chamber is a place of relative safety in a shaft or tunnel where tunnellers can be accommodated with access to basic life support services until rescued or it is safe for them to exit the tunnel. Refuge chambers should be easily identifiable and readily accessible by tunnellers at risk and by the emergency services This document will be reviewed and revised as necessary in the light of practical experience with the provision of refuge chambers in tunnels under construction. Comment and feedback is welcomed and should be made to the ITA Secretariat through the website www/ita-aites.org. Status of this document – this document is not intended to replace or override national standards. The “Guidelines” provide guidance and recommendations for good practice only. Compliance with the “Guidelines” is voluntary unless they form part of contractual requirements. This guideline was revised in 2018 to include guidance on the use of refuge chambers when there is a risk of flammable gas being present. Changes were also made in requirements concerning atmospheric monitoring equipment and controls for air conditioning equipment.