The state government now wants to turn the proposed 99-kilometer-long elevated corridor network that would crisscross the metropolis into subterranean highways. This is projected to cost around Rs 500 billion, and the government is eager to construct it through a public-private partnership (PPP), with the government partially subsidizing the project through a hybrid annuity model and recovering the investment through tolls. If this goes through, this might be the world's longest network of tunnel highways. A proposal to this effect was made at a review meeting by Deputy Chief Minister D.K. Shivakumar, who also holds the Bengaluru Development Department portfolio, held on Tuesday with representatives of Aecom, an international consultancy firm that has worked on multiple tunnel road projects across the world, including in Mumbai. Incidentally, the same firm had also prepared the Detailed Project Report (DPR) for the elevated corridor network project in 2017. If this proposal is implemented, the government will drop the elevated corridor project. The network crisscrosses the city with three major corridors: a North-South Corridor connecting Yelahanka to Silk Board Junction, two East-West Corridors connecting K.R. Puram and Goraguntepalya and Varthur Kodi and Jnanabharathi, and three connecting corridors totaling 99 km. K.J. George, who was Bengaluru Development Minister during the previous Congress regime, was the first to suggest both tunnel roads and an elevated corridor network. Despite substantial criticism from civic activists and urban transportation specialists, both plans were included in the Congress manifesto for the 2023 Assembly elections. Mr. Shivakumar has championed the tunnel road project since becoming office as a critical infrastructure boost to widen the city's roadway and reduce congestion. “The Minister thinks that apart from boosting public transport, given that the city is growing exponentially and the number of private vehicles have crossed 1 crore already, we also need to take up a mega infrastructure project to expand the roadways. Going underground will not obstruct traffic on the road either during construction or after completion like elevated corridors. They also do not lead to tree cutting. So the Minister is keen on the tunnel road network,” said a senior civic official. According to the official, tunneling technology has advanced significantly, and subterranean roads are becoming more prevalent around the world. Aecom, which is expected to be hired to do a feasibility study and DPR for the project, has already worked on the Smartwater Management and Road Tunnel (SMART Tunnel) in Kuala Lumpur, Malaysia, as well as other tunnel projects in Singapore and the Thane-Borivali Twin Tube Tunnel Road in Mumbai. According to sources, a delegation of civic authorities will soon trip Malaysia and Singapore to see these tunnel road developments. See also: 3 Bidders for Mumbai’s Goregaon – Mulund Link Road Tunnel ProjectVazhimukku-Kaliyikkavila road gets million for development