1. A project undertaken by TRANSIT NEW ZEALAND in conjunction with OPUS INTERNATIONAL CONSULTANTS LIMITED APEX PROJECT MANAGEMENT LIMITED and REGIONAL BRIDGE CONSULTANTS S E I S M I C S E C U R I T Y O F S T A T E H I G H W AY B R I D G E S I N N E W Z E A L A N D SCREENING & RETROFIT – PROGRESS SUMMARY S E I S M I C S E C U R I T Y O F S T A T E H I G H W AY B R I D G E S I N N E W Z E A L A N D SCREENING & RETROFIT – PROGRESS SUMMARY

2. 1 OBJECTIVE & STATUS To identify bridges that justify a more detailed seismic assessment and, possibly, retrofitting Seismic screening completed Retrofitting underway

3. 2 BACKGROUND Project drivers: Experience from earthquakes – integrity of the roading network is vital Dramatic improvement in performance often achievable from simple measures, e.g. linkages Past practice - since 1933, bridges either monolithic or have spans interlinked

4. 3 BACKGROUND Past retrofit policy – low cost seismic improvements in conjunction with work to raise service standards In early 1990s, 8 bridges in regions of higher seismicity retrofitted for linkages

5. 4 BACKGROUND Wellington’s Thorndon Overbridge and the Auckland Harbour Bridge retrofitted A screening procedure was developed Refer 12 th World Earthquake Conference ( Chapman et al )

6. 5 RISK ASSESSMENT Identification of structure vulnerabilities Classification of risk level for each risk event - likelihood & consequences likelihood derived from: peak ground acceleration causing risk event seismicity of site consequences derived from: effect on safety extent of traffic disruption

7. 6 ECONOMIC RANKING INDICATOR (ERI) For “high” and “significant” risks, an “Economic Ranking Indicator” determined “ERI” was based on factors such as: traffic volume duration & probability of disruption cost of traffic disruption cost of bridge damage (if significant) discounted cost (ROC) of retrofit

8. 7 RANKING Ranking was based on factors such as: Route priority Risk to Life ERI value Number of risk events

9. 8 OUTCOME 3813 bridges & culverts screened 2842 (75%) eliminated 971 (25%) subjected to risk assessment 381 (10%) “high” or “significant” risk level 188 (5%) separately identified as having linkage deficiencies $850 per bridge for 2322 bridges

10. 9 ASSESSING & RETROFITTING STRUCTURES Top 50 ranked structures will be assessed Available specialist resources likely to constrain the timeframe for assessments Expenditure ~ $5M to ~$6M per annum

11. 10 Bridge Seismic Screening Stage 2 Progress to date –Linkage Retrofit –Detailed Assessments –Detail Design & Construction Programme Management

12. 11 Progress to date Linkage Retrofit –P1 & P2 routes (130 comepleted) Detailed Assessments –Re-prioritised 50 completed detail assessments –On hold till first 25 bridges addressed Detail Design & Construction –Retrofits complete 10 –Retrofits under construction 5 –Designs in progress 6 –Recommended for replacement 2 ProgrammeTotalP1P2P3 Detail Assessments3351927271 Linkages173924536

13. 12 Programme Management Delegated authority Project Team –Rudolph/Gavin/John Wood/Howard Chapman Project Management Framework –Basis of seismic design for existing bridges. –Remaining life of structure & condition –Mode of failure –Performance indicators & risk profile –Retrofit vs. replacement cost –Route importance –Bridge Design Statement