The City of Lisbon in Portugal has published tender documents for the design and construction on extensions to its green and yellow line metro systems.
According to the documents published in the Official Journal of the European Union, the tunnelling work is valued at €120M (£107.7M).
The work is split into two lots and is designed to create a circular line by the end of 2021. The project were first announced in 2009.
The project will link the the southern terminus of the Green Line at Cais do Sodré and Rato on the Yellow Line to form a ring around the city centre with new stations at Estrela and Santos.
Lot one, valued at €52M (£46.7M), is for work between stations at Rato and Santos.
Lot two, valued at €68M (£61M), is for work between Santos and Cais do Sodré.
Bids for the work must be received by 7 February.