Túnel do TejoCais do Sodré – Cacilhas
PT

Sheet 08 · References

Sources & glossary

Where the numbers come from, how the estimates were made and what the technical terms mean.

Project
TT-CS-CC
Sheet
08
Rev.
A
Date
2026-11

01Cited sources

Numbers marked [n] throughout the site point to this list. Links open the original source.

  1. Hydro-morphological study, measurements and calculation of expected siltation (Tagus estuary). TU Delft Repository. repository.tudelft.nl/record/uuid:4858ca0d-d38d-4059-84d1-7eda1918a278. Accessed 2026-11-15.
  2. High-resolution bathymetry — Rio Tejo (Lisboa). EMODnet Bathymetry. emodnet.ec.europa.eu/geonetwork/srv/api/records/SDN_CPRD_590_HR_RioTejo. Accessed 2026-11-15.
  3. Active faulting in the Lower Tagus Valley (alluvial cover ~50 m). LNEG / Universidade de Évora repository. rdpc.uevora.pt/bitstream/10174/40476/1/CARVALH0_LNEG_2024.pdf. Accessed 2026-11-15.
  4. The Miocene of Lisbon and the Lower Tagus Basin. Ciências da Terra (NOVA). cienciasdaterra.novaidfct.pt/index.php/ct-esj/article/view/22/20. Accessed 2026-11-15.
  5. The 1755 Lisbon earthquake and tsunami: source and impacts. NSF Public Access Repository. par.nsf.gov/servlets/purl/10522014. Accessed 2026-11-15.
  6. Probabilistic seismic hazard for mainland Portugal (GeoHazards, 2024). MDPI. www.mdpi.com/2624-795x/5/3/47. Accessed 2026-11-15.
  7. Cacilhas — ferry, metro and bus station. lisbonlisboaportugal.com. lisbonlisboaportugal.com/lisbon-transport/Cacilhas-ferry-metro-bus-station.html. Accessed 2026-11-15.
  8. Dois milhões de passageiros transportados em navios elétricos. Governo de Portugal. portugal.gov.pt/gc25/comunicacao/comunicados/dois-milhoes-de-passageiros-transportados-em-navios-eletricos. Accessed 2026-11-15.
  9. Metro Transportes do Sul (Almada / Seixal). UrbanRail.Net. www.urbanrail.net/eu/pt/lisboa/almada.htm. Accessed 2026-11-15.
  10. Metro de Lisboa com aumento de 6,5% de passageiros transportados em 2024. Executive Digest. executivedigest.sapo.pt/metro-de-lisboa-com-aumento-de-65-de-passageiros-transportados-em-2024. Accessed 2026-11-15.
  11. Metro de Lisboa — apresentação institucional (frota, unidades triplas). ALAMYS. alamys.org/wp-content/files_mf/15626838913.MetrodeLisboaJorgeFerreira010719.pdf. Accessed 2026-11-15.
  12. Metro retoma circulação com 4 e 6 carruagens nas linhas Amarela e Verde. Notícias ao Minuto. www.noticiasaominuto.com/economia/2339476/metro-retoma-circulacao-com-4-e-6-carruagens-nas-linhas-amarela-e-verde. Accessed 2026-11-15.
  13. Eliminate redundant subway cross passages (NFPA 130 800 ft spacing). Institute for Progress. ifp.org/eliminate-redundant-subway-cross-passages. Accessed 2026-11-15.
  14. Current practice on cross-passage design to support safety in rail and metro tunnels. ITA-COSUF. about.ita-aites.org/wg-committees/ita-cosuf/publications/1724/current-practice-on-cross-passage-design-to-support-safety-in-rail-and-metro-tunnels. Accessed 2026-11-15.
  15. Decreto-Lei n.º 565/76 — Reserva Natural do Estuário do Tejo. Diário da República. diariodarepublica.pt/dr/detalhe/decreto-lei/565-1976-430600. Accessed 2026-11-15.
  16. Ramsar Information Sheet — Estuário do Tejo (site 211). Ramsar Sites Information Service. rsis.ramsar.org/ris/211. Accessed 2026-11-15.
  17. Decreto-Lei n.º 280/94 — ZPE do Estuário do Tejo. Diário da República. diariodarepublica.pt/dr/detalhe/decreto-lei/280-1994-535379. Accessed 2026-11-15.
  18. Marmaray Tunnel. Wikipedia. en.wikipedia.org/wiki/Marmaray_Tunnel. Accessed 2026-11-15.
  19. Fehmarnbelt: world’s longest immersed tunnel. Ramboll. www.ramboll.com/fehmarnbelt-worlds-longest-immersed-tunnel. Accessed 2026-11-15.
  20. TunnelTalk Annual Review 2010 (immersed tunnel comparison). TunnelTalk. tunneltalk.com/TunnelTalk-Annual-Review-2010-Digital-Issue/files/basic-html/page10.html. Accessed 2026-11-15.
  21. OpenStreetMap — Cais do Sodré and Cacilhas waterfront geometry. OpenStreetMap contributors. www.openstreetmap.org/#map=15/38.6966/-9.1460. Accessed 2026-11-15.
  22. 60 years uniting banks: 25 de Abril Bridge remains Portugal’s busiest crossing. Euronews. www.euronews.com/2026/08/06/60-years-uniting-banks-25-de-abril-bridge-remains-portugals-busiest-crossing. Accessed 2026-11-15.
  23. Eurocode 8: general overview and the Portuguese National Annex (E. Carvalho). European Commission JRC — Eurocodes. eurocodes.jrc.ec.europa.eu/sites/default/files/2022-06/S1_EC8-Lisbon_E%20CARVALHO.pdf. Accessed 2026-11-15.
  24. Promotor da Cidade da Água em Almada terá de suportar custo das infraestruturas. Diário de Notícias. www.dn.pt/arquivo/diario-de-noticias/promotor-da-cidade-da-agua-em-almada-tera-de-suportar-custo-das-infraestruturas-10896527.html. Accessed 2026-11-15.
  25. The Lower Tagus Valley fault zone: active faulting and historical earthquakes (EGU2010-12498). EGU General Assembly 2010. meetingorganizer.copernicus.org/EGU2010/EGU2010-12498-4.pdf. Accessed 2026-11-15.
  26. Reparation of the Terreiro do Paço tunnel, Lisbon. TEC Tunnel Engineering Consultants. tec-tunnel.com/en/tunnelling-projects/reparation-terreiro-do-paco-tunnel-lisbon. Accessed 2026-11-15.

02How to read the numbers

We use two kinds of figures. Real data comes from published sources and carries a [n] reference. Estimates are design values derived from real data and comparable projects, and always carry an Estimate tag. Hover an estimate to see its assumption.

We found no published figures for the exact width and depth along the alignment, nor site boreholes. These are treated as estimates and will be confirmed by the 2029–2031 surveys.

Estimates and assumptions
ValueAssumption
1,800 m EstimateMeasured shore to shore on OpenStreetMap along the alignment.
32 m EstimateLower-estuary channel of ~30 m plus local scour allowance; to be confirmed by bathymetric survey.
2,300 m EstimateDistance between station centres (~2.06 km straight line) plus alignment curves.
59 m EstimateLow point of the long section (tunnel invert), with drainage sump.
27 m EstimateInvert at −59 m below a seabed at −32 m.
70 m EstimateNo boreholes on the alignment; inferred from the 25 de Abril Bridge south pier foundation (~80 m), 2 km downstream. To be confirmed by the ground investigation.
10 m EstimateDesign criterion ≈ 1.5 × bore diameter, against blow-out and flotation.
6.3 m EstimateRolling-stock gauge, track, evacuation walkway and equipment.
7 m Estimate0.35 m precast concrete segmental lining.
4 % EstimateCommon metro limit.
240 m EstimateMeets NFPA 130 (≤ 244 m), stricter than TSI SRT (≤ 500 m).
28 m EstimateStation invert level to pass below waterfront foundations.
110 m Estimate6-car train (2 × 50 m) plus stopping tolerance.
20,000 pphpd Estimate20 trains/h (3 min) × ~1,000 passengers per 6-car train.
30,000 pphpd Estimate30 trains/h (2 min) with CBTC signalling.
3 min Estimate2.3 km at ~45–50 km/h average including acceleration.
75,000 EstimateRange 60–90k: Cacilhas ferry users, a share of the 25 de Abril bridge corridor, MTS tram feeder trips and induced demand.
1.9 € bn Estimate2026 prices; range €1.6–2.3 bn; tunnel ~0.7, stations ~0.45, systems, rolling stock, depot and design ~0.39, ~25% contingency.
2040 EstimateProgramme target with ~12 months float.

03Glossary

Tunnel boring machine (TBM)
A machine that excavates the tunnel and builds its lining at the same time, like a mechanical “mole”. Here: slurry TBMs, which balance water and ground pressure at the face with pressurised bentonite.
Immersed tube
A tunnel made of large concrete elements built in a dry dock, floated out and sunk into a trench dredged in the riverbed.
Segments
Precast reinforced-concrete pieces that, assembled as a ring, form the tunnel lining.
Cross-passage
A passage between the two bores that serves as an emergency exit into the neighbouring tunnel, which acts as the place of safety.
Cover
Thickness of ground between the top of the tunnel (crown) and the ground surface or riverbed.
Invert / crown
The lowest and highest points of the tunnel’s internal cross-section.
Chainage
Distance measured along the alignment from an origin, here the centre of Cais do Sodré station. 1+150 means 1,150 m.
MSL
Mean sea level: the reference for the levels shown.
Diaphragm walls
Reinforced-concrete walls cast in the ground in panels before excavation, which retain soil and cut off water.
Top-down construction
Method in which the roof slab is built first and excavation continues beneath it, returning the surface early.
Liquefaction
Loss of strength of saturated sandy soils during an earthquake, which then behave like a liquid.
Peak ground acceleration (PGA)
Maximum ground acceleration in an earthquake, as a fraction of gravity (g). Used to design structures.
CBTC
Communications-based train control, which lets trains run closer together safely.
pphpd
Passengers per hour per direction: the measure of a line’s capacity.
EIA
Environmental Impact Assessment: the legal procedure, with public consultation, that assesses and conditions a project.
Float
Time margin in the programme that absorbs delays without moving the opening date.
Alluvium
Recent sediments (silts, sands) deposited by the river; soft and water-bearing.
Miocene
Geological formations about 23 to 5 million years old (clays, sands and limestones) that form the firm ground beneath Lisbon and Almada.