The Mumbai-Ahmedabad Bullet Train project successfully completed the third mountain tunnel in Maharashtra within five months, marking another milestone in the construction of India’s first high-speed rail corridor.This success happened in Dahanu taluka of Palghar district of Maharashtra.“Mumbai-Amdabad bullet train project achieves another milestone…3rd mountain tunnel in Maharashtra within 5 months. Dahanu taluka, Palghar,” Union Railway Minister Ashwini Vaishnav posted on Twitter on Tuesday.The latest breakthrough comes as construction activity on the 508-km Mumbai-Ahmedabad High-Speed Rail (MAHSR) corridor has picked up pace, almost nine years after Prime Minister Narendra Modi and former Japanese Prime Minister Shinzo Abe laid its foundation stone in Ahmedabad in September 2017.Bridges are going up in both states, work on an undersea tunnel near Mumbai has begun, stations are taking shape, and India’s first indigenously developed high-speed trainset is expected to be operational by 2027.Among the recent milestones, the project has completed the commissioning of a railway over bridge (ROB), a bridge over Kalupur flyover on the Sabarmati-Mumbai main line of Western Railway in Ahmedabad district.According to an official release, the viaduct runs parallel to the existing railway line and the launching on the flyover was completed on Monday. The work included the laying of a 45 meter long bridge using the span-by-span (SBS) method.The bridge has a 45-metre span over the flyover, a 19.5-metre viaduct from ground to rail level, 19 sections and a total span weight of 1,200 metric tonnes.Kalupur flyover is one of the busiest two-lane flyovers of Ahmedabad, connecting Shahibagh, Asarwa and Kalupur, and is used by thousands of commuters daily.The Mumbai-Ahmedabad Bullet Train corridor passes through 31 crossings in Ahmedabad district, the release said. These include eight Indian Railway crossings, one road flyover, roads, road underpasses, 16 canal crossings, one bridge crossing over the Sabarmati river and six steel bridges. Of these, work on 23 crossings has already been completed.The Mumbai-Ahmedabad high-speed rail project is being developed with technical and financial assistance from Japan using the Shinkansen system. The 508 km long corridor will pass through Maharashtra, Gujarat and the union territories of Dadra and Nagar Haveli and Daman and Diu.According to the Railway Ministry, the route will have 12 stations – Mumbai, Thane, Virar, Boisar, Vapi, Bilimora, Surat, Bharuch, Vadodara, Anand, Ahmedabad and Sabarmati. The project is being implemented by National High Speed Rail Corporation Limited (NHSRCL).The corridor is designed for trains running at speeds of up to 320 kmph. According to railway estimates, the fastest service on the route, which stops only at Surat and Vadodara, is expected to complete the journey in a little over two hours. Currently, regular trains on this route take around seven hours, while Vande Bharat Express takes around five and a half hours.Railway officials have said that the Mumbai-Ahmedabad corridor was chosen because it is one of the busiest business travel routes in India. Mumbai remains the financial capital of the country, while Ahmedabad, Surat and Vadodara are major industrial and commercial centres. Passenger demand projections, economic feasibility study, expected urban growth and travel density were the main reasons behind selecting the route.The project was also conceived as a technology-transfer initiative under the government’s “Make in India” programme. Japan agreed to finance about 81 percent of the project through a soft loan with an interest rate of 0.1 percent, repayable over 50 years with a long moratorium period.