Construction is expected to start next year, The Straits Times reported.
“We remain on track to commence the Kuala Lumpur-Singapore express service by 2026,” an LTA spokesman said.
LTA said the tenders for the design and construction of twin-bored tunnels and other facilities were called on April 6.
Tenders for the design and construction of cut-and-cover tunnels leading into the Jurong East terminus meanwhile were called on April 11.
Tunnel-boring machines will be used for longer stretches of underground excavation as they cause less disturbance to surface utilities, buildings and structures.
Cut-and-cover tunnels are for shorter distances. They use retaining structures, with excavation taking place in stages.
LTA said the remaining civil tenders would be called in the coming months.
Project delivery partners picked for KL-S’pore high-speed rail