The Coatzacoalcos immersed tunnel

The first immersed tunnel in Latin-America

The Coatzacoalcos immersed tunnel is in the State of Veracruz, Mexico and connects the urban centre of the City of Coatzacoalcos, the main industrial port of Mexico, with Villa de Allende, both of which are on the banks of the River Coatzacoalcos mouth.

The project for this immersed tunnel across the River Coatzacoalcos in the State of Veracruz, Mexico, is the first works of these characteristics in this country and also the first in Latin-America executed with reinforced concrete, using pre-stressed concrete caissons, subsequently sunk onto the river bed and then all connected together.

The works consist of the opening and execution of a 2,280 metre long roadway and four circulation lanes, two in each direction, 3.50 metres wide along the uncovered section and 3.75 metres in the tunnel section that communicates the Villa de Allende and the City of Coatzacoalcos, which are separated by the river of the same name as the latter. In both cases, there is a 1.00-metre verge and/or pavement.

Of the 2,280 metres of project development, it is proposed to resolve 1,125 metres in the tunnel as follows: 696 metres of immersed tunnel and another 429 metres using the cut and cover method, of which 200 metres are on the west or Coatzacoalcos side and 229 metres on the Allende side. Both areas are accessed by transition sections or ramps, with 180 metres on the west side and somewhat more than 155 metres on the east side.

The immersed tunnel is constructed of reinforced concrete and it is also pre-stressed longitudinally in order to withstand the seismic load that can cause additional shear forces and bending moments along the horizontal and vertical planes of the tunnel elements (snaking), while the longitudinal seismic wave produces compression and tension in the immersion joints. 

The transverse section is 25.1 x 9.2 metres, with two interior free spaces of 5.5 x 9.5 metres and a 1.4 x 6.45-metre central service gallery prepared for housing the specific installations for tunnel operation and control and also as an evacuation route in an emergency.
The deepest central part of the immersed tunnel is supported at approximately elevation -30 metres, below the mean water level, which is around fifteen metres below the deepest bathymetric line obtained at the location point.

The Coatzacoalcos Tunnel represent technological innovation in construction, because the Immersed-tunnel Method allows the prefabrication of reinforced concrete tunnel sections in a dry dock, prepared to be floated, tugged and positioned on the marine bed without any need for special subsoil drilling equipment

The project also includes two buildings or portals on the east and west sides, located on both sides of the immersed tunnel, that house the electromechanical installations.

A control building is also installed on the toll plaza that fulfils the functions of administration and control.

The project includes all the required installations for adequate works operation and control, together with the lighting system, ventilation system, carbon monoxide detection system, the SOS system, the fire detection system, the variable sign system, the CCTV system and the public address system.

The tunnel includes an integral safety system, with video-surveillance and control for real-time monitoring and control of tunnel status, thus guaranteeing its efficient management and ensuring user safety.

The project took into account that navigation along the River Coatzacoalcos during works execution was not to be affected.

Remarkable aspects

  • The first immersed tunnel in Latin-America.
  • Constructed using the Immersed-tunnel Method that did not require the use of any special subsoil drilling equipment.

Client: Veracruz State Government

Start date: 2007

End date: Under construction