COMSA Montcada i Reixac railway tunnel contract https://www.comsa.com/en/infrastructures/comsa-ejecutara-las-obras-para-el-soterramiento-del-ferrocarril-en-montcada-i-reixac/

Lyon Turin Tunnel - VINCI https://www.vinci.com/vinci.nsf/en/press-releases/pages/20231017-1745.htm

Ontario Line Map - credit: Infrastructure Ontario, Canada. https://www.infrastructureontario.ca/en/what-we-do/projectssearch/ontario-line---north-pape-tunnel-and-underground-stations/

Spain Mitma diagram for AC-14 road connection with AP-9, in A Corua from Mitma media information.

Toad reconditioning between the Balupor and Fiscal tunnel https://www.mitma.gob.es/el-ministerio/sala-de-prensa/noticias/mar-19092023-1213

GDDKiA Tenders in progress - as of September 6, 2023 from: https://www.gov.pl/web/gddkia/umowy-i-przetargi-2023-w-liczbach

GDDKiA Signed contracts for implementation in 2023 - as of September 6 from: https://www.gov.pl/web/gddkia/umowy-i-przetargi-2023-w-liczbach

GDDKiA 20230908 Tenders announced in 2023 - as of September 6 from: https://www.gov.pl/web/gddkia/umowy-i-przetargi-2023-w-liczbach

Austria Ofenauer Tunnel - Tauernautobahn Author and licence: High Contrast, CC BY 3.0 DE, via Wikimedia Commons https://commons.wikimedia.org/wiki/File:Ofenauer_Tunnel,_Tauernautobahn.JPG

Prague Metro plan development of new route D Prague Metro D line. Metra D, Praha drawing: DPP Prague Public Transport Company.