A 3D BIM model was used to track the projected carbon footprint of Auckland’s largest transport project, the City Rail Link (CRL), marking a first for both Australia and New Zealand.

Downer’s digital engineering team collaborated closely with the client, designers, construction teams, and mechanical, electrical and plumbing subcontractors to develop a LOD 400 Construction BIM model, which enhanced construction planning and execution. As the design evolved, the BIM model was regularly updated, and with monthly take-offs generated to quantify materials used across design packages. These quantities were then translated into carbon footprint estimates by the Sustainability team and benchmarked against the reference design.

Additionally, the use of BIM enabled 4D modelling—incorporating time as a fourth dimension—to visualise construction phases and test sequencing options. This enabled improved efficiency in time, materials, and energy use.