During today's webinar on Australian Capital Projects – Risk Management, Project Controls and COVID-19 Pedram Danesh-Mand mentioned some useful references for calculating contingency and escalation in projects. I've posted them here for easy reference.
Risk Engineering Society Contingency Guideline: https://rebok.engineersaustralia.org.au/search/?q=contingency&quick=1
Australian Government Cost Estimation Guide: https://investment.infrastructure.gov.au/about/funding_and_finance/cost_estimation_guidance.aspx
Pedram also mentioned some guidelines for escalation from the AACEI, which he recommended as a secondary reference for Australian projects. The full documents are only accessible to AACE members, but links to samples are below:
http://web.aacei.org/docs/default-source/toc/toc_58r-10.pdf
https://web.aacei.org/docs/default-source/toc/toc_68r-11.pdf?sfvrsn=4