Chile's public works ministry (MOP) has launched a consultancy tender for a low-altitude railway tunnel connecting Chile and Argentina.
The winning firm will be responsible for making sure technical, environmental impact and other studies for the project are technically sound.
Interested firms may present bids until October 25 and MOP expects to award the tender November 12, according to information published on e-procurement portal ChileCompra.
A multinational consortium led by Argentina's Corporacion America (CASA), including Japan's Mitsubishi, Italy's Geodata and Chilean company Empresas Navieras, aims to begin technical and geological studies for the 52km tunnel by year-end, BNamericas reported previously.
Chilean and Argentine authorities declared the US$3bn private initiative of public interest last year.
The tunnel will be built at an altitude of 2,000-2,500m and aims to relieve traffic congestion on the Los Libertadores mountain pass, which handles up to 80% of trade between Chile and Argentina and is often closed in winter due to bad weather.