As metros reach a certain age and subsystems need to be replaced, operators or authorities responsible for metros should consider different options to modernise their system. Upgrading to fully automated metro operations (Grade of Automation 4, or GoA4), although complex, is an option which is being chosen for a growing number of lines.
The benefits of full metro automation are widely known today. However, fully automating existing lines (brownfield) is far from being as obvious a choice as to choose GoA4 for a new line (greenfield). In addition to a cost benefit analysis, Public Transport Authorities (PTA) and Public Transport Operators (PTO) should understand the multiple challenges from a technical, project management and human resources point of view.
This paper aims to support organisations and companies that are considering, planning or implementing GoA4 migration projects. However, many of the issues for such projects are common to migration to GoA2, as well as GoA2-to-GoA3 and GoA4-to-GoA4 migration. The final section of this paper explains which are the common challenges between GoA4 upgrades and other upgrades, and the differences between them.