Mato Grosso Approves Pre-Project for 513-Meter Tunnel at Portão do Inferno
The Mato Grosso State Secretariat of Infrastructure and Logistics (Sinfra) has approved a pre-project for a 513-meter tunnel at the Portão do Inferno site, located on the MT-251 highway connecting Cuiabá and Chapada dos Guimarães. This pre-project outlines the chosen engineering solution and will serve as the basis for future construction phases. A technical commission selected this proposal after evaluating various alternatives. Since March 2024, the MT-251 has experienced partial closures for the removal of fallen rocks from the mountainside, according to Sinfra. The state government believes this tunnel project will permanently resolve the frequent landslides that cause road disruptions. The company that developed the pre-project is not guaranteed to be the one that builds the tunnel; a new bidding process will be launched to select the construction firm. However, environmental permits from the Brazilian Institute of Environment and Renewable Natural Resources (Ibama) are required before construction can begin. Previously, the state only had authorization for highway duplication, not tunnel construction. Despite eight different proposals submitted to Ibama for the site, none have been approved due to the complexity of the intervention. With the pre-project's approval, a new licensing request has been filed and is under review by Ibama. While awaiting Ibama's decision, the government is preparing to re-tender the construction contract, as the initial bidding process for a different project attracted no interested companies. The new tender is expected to be published in the coming weeks, though no specific date has been set. The tunnel became the preferred solution after nearly two years of instability at Portão do Inferno, marked by the constant risk of rockfalls. An earlier plan in June 2025 involving the excavation of 180,000 cubic meters of rock (retaludamento) raised concerns among environmental researchers about ecological impacts and the project's safety. Governor Mauro Mendes stated that emergency geological studies during the initial intervention revealed inconsistencies casting doubt on the viability of cutting the cliffs, particularly with heavy machinery, as initial soundings were insufficient to fully map the area's geology.
The approval of the Portão do Inferno tunnel pre-project signifies a shift towards a more permanent infrastructure solution for a geologically unstable region. This move addresses recurring safety and logistical challenges on the MT-251, which have led to frequent road closures and necessitated costly emergency rock removal. The project's progression highlights the tension between infrastructure development needs and environmental considerations, as evidenced by the multiple rejections from Ibama and the shift away from the retaludamento plan due to ecological and safety concerns. Future success will depend on navigating the complex environmental licensing process and ensuring the selected construction method is both technically sound and environmentally responsible, considering the long-term implications for regional connectivity and ecological balance in the next decade.
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