The South Island Line (East) will be built on viaducts and within tunnels. The underground construction works include excavation of rail tunnels, pedestrian subways and underground stations at Admiralty, Lei Tung and South Horizons. Construction of the stations at Ocean Park and Wong Chuk Hang will use elevated viaducts.

The majority of the underground sections are in rock and excavation is undertaken using the drill and blast method; in some sensitive areas at shallow levels and where the drill and blast method is not feasible, excavation is carried out by mechanical means. For shallow excavation in soft ground cut and cover method is used. Moreover, the open blast method will be used for the site formation works of the South Island Line (East) depot at the ex-Wong Chuk Hang Estate. It is more effective than mechanical excavation and has less impact on the public. Monitoring points will also be installed to determine any possible impacts on adjacent building structures and ensure the public safety.