Beginning tomorrow, commuters travelling between Mumbai and Pune will have two options: take the usual scenic route through the Western Ghats, or zip through the hills and valleys in under 10 minutes.The inauguration of the Missing Link on the Mumbai-Pune Expressway on Friday (May 1), with its tunnels and bridges, will cut travel time between the cities by 6 km, translating into at least a 30-minute reduction.Maharashtra Chief Minister Devendra Fadnavis will inaugurate the project at around 12.30 pm, where it will also attempt to secure a Guinness World Record stamp for the world’s widest road tunnel. The project is a feat of engineering that will also help make travel safer. Here is how.Safe travelsCurrently, those travelling between the two cities take either the six-lane, 94-km-long Mumbai-Pune Expressway or the old Mumbai-Pune Highway (or National Highway No. 4), a four-lane, 111-km road stretching from Shil Phata to Dehu Road.But somewhere near the Khalapur toll plaza, the traffic merges, creating a bottleneck until the Khandala Exit, as the traffic of 10 lanes converges on six lanes of the expressway. Besides, this stretch passes through ghats and is prone to landslides during monsoons, leading to further congestion.“The Missing Link is the permanent solution to the traffic on the Ghat section,” said Anilkumar Gaikwad, Managing Director of the Maharashtra State Road Development Corporation Limited. “It will reduce the incidence of accidents and make travel between the two cities quicker and more reliable.” How Mumbai Pune Missing Link will help.Comprising a series of bridges and tunnels, the Missing Link offers an alternative to the 19.8 km-long Ghat section, which has a history of accidents and traffic jams due to its sharp curves and steep inclines. The stretch sees a mix of vehicles, heavy vehicles and tourist traffic to Lonavala. Most recently, the toppling of the 21,000 kg propylene gas tanker in February threw the entire E-way out of whack for 32 hours.Story continues below this adCut to May 1, when a 13.3km-long road offering drive speeds of 100km/hour will become a possible option.The Rs 6,695-crore project comprises two sets of twin tunnels and two viaducts, one of which is a cable-stayed bridge. From Mumbai, the Missing Link project starts at Khopoli, beginning with a viaduct. A tunnel follows, carved out through a hill for 1.58 km, just as a trailer to the one that’s coming a few metres ahead.What follows is a small but impressive stretch hanging high up — 125 m to be exact — over Lonavala’s famous Tiger Valley. A 182 m-tall cable-stayed bridge has been deemed India’s tallest bridge of its kind. Chosen for its minimal piers, given the forest beneath, building the bridge meant creating a structure that could withstand the force of fog, rain and wind during monsoons. Missing Link cable bridge.The last stretch of the Missing Link is an 8.9 km-long, 23.5 m-wide tunnel. This detail is what might get it the World Record for being the world’s widest urban tunnel, which goes 180 m under the Lonavala lake.Story continues below this adTo get to the tunnel alignments in the middle of the hills, temporary adits or passages had to be dug through on steep inclines. Using the New Austrian Tunnelling Method, the workers then bored through the hard basaltic rock of the Sahyadris. Tunnel 2 of the Missing Link.Long in the worksWork began in 2018, requiring testing with models in Copenhagen and London to perfect the design and materials.But even before then, the Missing Link had been a long time coming. Pre-dating the Mumbai Pune Expressway, in 1995, the public engineering services company RITES recognised the necessity of such an alternative to the Ghat section. Shelved for a later date, its need only grew over time, with long weekend travel gaining popularity and not-so-infrequent accidents.Story continues below this adWork on the Missing Link picked up once again in 2017, with the Maharashtra Cabinet’s approval. Construction work began in 2019 after obtaining the requisite approvals, but Covid-19 threw another spanner in the works. The initial deadline of 2022 was long past.Then came the actual challenges during construction, with four months of monsoon. “The high wind speeds and wind vortex were a concern, which is why we installed four tower cranes measuring wind speeds at all times that would blare when the limit was reached to signal that work was not safe to continue,” said an official from PINNI & Louis Berger International, the consultant on the project.Despite last-minute challenges, with the West Asia conflict making bitumen and waterproofing material scarce, the project has finally come to fruition. On Friday, as the inauguration coincides with Maharashtra Day, the Missing Link of the Mumbai Pune Expressway will finally fit into place.