Latin-American pioneer in tunnel construction
Located in the north-western corner of the South American cone, Colombia is the only country in South America with three mountain ranges of the Andes (western, central, and eastern) and ports within the Atlantic and the Pacific oceans. However, since its productive clusters are located mainly inland and 93% of freight transportation is carried out on land, improving its competitiveness depends to a large extent on its physical connectivity. In view of this, the country has developed five generations of road PPP programs over the last 25-30 years.
New road construction and improvement of existing highways must face steep slopes, presence of geological faults and high rainfall zones. These features could lead to interruptions to traffic movements if the infrastructure is not resilient enough and not built with the capacity to sustain at least minimum service in adverse weather conditions. In recent years, the need to improve competitiveness of land transport in the country has led to the construction of tunnels not only to shorten travel times, but also to have the ability to cope with extreme weather events.
The development of the 4G PPP program, which included the construction of additional carriageways and the improvement of design specifications of the existing highways, required projects to overcome complex topographical conditions of the country. Thus, in recent years Colombia has become a reference for the construction of tunnels, currently having 8 of the 10 longest tunnels in Latin America and with approximately 50 tunnels under development or improvement. The most recent 5G PPP Program estimates approximately 100 km of tunnels are being planned and designed in three Colombian mountain ranges for years to come. Colombia will have an inventory of 250 road tunnels, of which 200 have been built during the last ten years: 94 through the 4G program, 32 though the 5G program, and 75 that are being planned of built through the public works scheme.
In terms of public investment, Colombia has spent about 6.5 billion USD for these initiatives, which represents about 56% of the total CAPEX of the 4G Concessions, out of a total of 11.75 billion USD that the program is worth. As for the 5G program, it will strengthen multimodality between roads, rail, airports, and ports and 14 of 15 projects that make up the first of two waves of contracts will be awarded in 2021, with a total CAPEX investment of 5.5 billion USD. These projects will offer more than 62,000 jobs, specially in the regions where they will be developed.
The 4G and 5G PPP schemes in Colombia led to the entry of new lenders to finance large infrastructure projects. With this new financing, Colombia could begin with the construction of complex projects that include the construction of tunnels. The role of the Lender’s Technical Advisor – LTA – in this type of project is essential as it provides the certainty needed to the lenders to secure the financing. Currently in Colombia, Infrata is carrying out the role of LTA in the construction monitoring of several road concessions. Some of the projects with substantial tunnelling components include Ruta del Cacao (La Paz 3.2 km and La Sorda 2.1 km), Autopista al Mar 2 (12 tunnels with a total length of 6.1 km) and Unión Vial Río Pamplonita (Pamplona 1.4 km, Pamplonita 0.96 km, and La Honda 0.48 km).
Ultimately, the experience accumulated in recent years and the continuous demand of the tunnel sector led the National Institute of Roads (INVIAS) to present the first edition of the Manual of Design, Construction, Operation and Maintenance of Highway Tunnels in 2015. This aimed to establish the minimum requirements for the proper functioning of tunnels under road safety conditions and to set up appropriate road designs for the topographic conditions and the automobile fleet. Such is the recent learning in the construction of tunnels in the country, that the Manual has been updated to include modern techniques such as TBM (Tunnel Boring Machine).
Although the Colombian experience in the construction of tunnels has grown exponentially in recent years, there are also new challenges in the execution of this type of infrastructure. The construction of new tunnel projects comes with the necessity of allocating greater resources for geological and geotechnical research. Also, it requires that the construction techniques applied are the most adequate to the region and that concepts of resilient infrastructure are included for a better climate adaptation.