Of geotechnical and geophysical -- pr) operies 160 -- 10. 3 4 Design of tunnel linings 1 61 -- 10. 4 Instrumentation of the CTRL North Downs Tunnel 164 -- 10. 5 References 165 -- Appendix I Abbreviations and symbols 166 -- Appendix 2 Risk management 168 -- A2l Introduction 168 -- A2. 2 Scope 168 -- A23 Risk register 169 -- A21. 1 When to use the risk register 169 -- A2. 32 Whalt is it? 169 -- A2. 3. 3 Assessment process 169 -- A2. 3. 4 Key steps 169 -- A2. 3. 5 Risk assessment, qualitative or -- quantitative? 171 -- A2. 3. 6 R anaingt risk 175 -- A2. 4 References 17.