Phase 1 The foundation stone for construction of Phase-1 was laid by then Prime Minister Dr.
Manmohan Singh on 24 June 2006. Navayuga Engineering Company Limited was awarded the first contract to construct Reach-1 of the east–west corridor (named Purple Line later) in 2006. Civil construction on the first section (Reach-1) of the Purple Line between
Baiyyappanahalli and
Mahatma Gandhi Road, commenced on 15 April 2007. Detailed Project Reports (DPR) for a northern extension (from
Yeshwanthapura to
Nagasandra) and a southern extension (from
Rashtreeya Vidyalaya Road to
Yelachenahalli) of north–south corridor (named Green Line later) was submitted in October 2007 and June 2008 respectively. With these extensions, the total route length for Phase 1 became . The objective was to connect the metro to the
Outer Ring Road at northern and southern ends, and also cover the industrial areas of
Peenya in the north-west, thereby providing better connectivity and increasing ridership. In October 2008, the
Government of Karnataka approved this extension, which would cost an additional ₹1,763 crore (US$250 million).
Underground section Both lines in Phase-1 have tunnel sections in the city center, which are also the first metro tunnels built in
South India. Construction of underground sections in Phase-1 commenced in late 2012. The delay was due to cancellation of the initial tenders called in early 2008 as the entire DPR had to be revised and bids received were too high. A second round of tendering was done in late 2009 with the gigantic
Majestic inter-change station as a separate package. Bids were awarded for the tunnel sections in 2011 and construction began in 2012. The tunnels bored with
tunnel boring machines (TBMs), located approximately below ground level, have a diameter of and are apart. The TBMs were nicknamed
Helen,
Margarita,
Kaveri,
Krishna and
Godavari. Tunnel boring of underground section UG1 (on east–west corridor) was completed on 17 March 2014. Track works and 3rd rail electrification works were completed on the east–west tunnel of the Purple line between Cubbon Park and Magadi Road and Bangalore Metro Rail Corporation Ltd (BMRCL) began trials on 23 November 2015. The entire stretch of the Purple Line was opened on 29 April 2016. Tunnel boring of underground section UG2 (on north–south corridor) was completed on 23 September 2016. The tunneling faced a major delay when the cutter head of TBM Godavari was broken and spares had to be awaited. Trial runs on the east–west tunnel of the Green line between Sampige Road and National College were commenced on 31 March 2017. The entire stretch of Green Line was opened on 19 June 2017, thus completing Phase-1 of the project. train
Opening After missing deadlines, Namma Metro's first section (Reach-1) finally opened to the public on 20 October 2011. There was an overwhelming response by the public at commencement of operations. As per BMRCL sources, within the first 3 days of operations 169,019 people rode the metro. At the end of the 4th day, about 200,000 passengers had already commuted on Namma Metro. Namma Metro's first 12-day cumulative revenue was ₹1 crore (US$100,000). The northern section of Green Line (Reach 3, 3A, 3B) was initially scheduled to be opened by the end of 2012. However, it was delayed and finally opened on 1 March 2014. BMRCL MD Pradeep Singh Kharola stated that about 25,000 passengers travelled on the line on the opening day. Once the east and west reaches were inter-connected with opening of the underground section of the purple line, ridership surged significantly. After the north–south underground section was opened (simultaneously with the elevated reach 4,4A in the south), the network provided connectivity in all four directions with interchange between the lines and this further increased ridership. Ridership kept increasing and was around 4,50,000 daily (September 2019).
Phase 1 lines and sections train Phase-1 consists of two lines spanning a length of , of which about is underground and about is elevated. The first phase of the project was initially budgeted at ₹6,395 crore (US$875 million). With route extensions and cost escalation, this was later revised to ₹11,609 crores (US$1.6 billion). There were many delays during construction, as a result, there were several postponements. The difficult geological conditions below ground with a mix of soft soil, high groundwater levels, hard granite and large boulders was a major impediment for tunnel boring. A major delay was due to a broken cutter head of TBM Godavari for which spares had to be ordered from Italy. Phase 1, containing two lines aggregating was completed and services opened to the public on 19 June 2017. The final cost for Phase 1 was ₹14,405 crores.
Phase 2 The State Government accorded approval for preparation of the detailed project report (DPR) for Phase 2 by DMRC on 4 January 2011. The high power committee (HPC) gave in-principle clearance to proceed with Phase-2 in July 2011. Karnataka government gave in-principle approval to Phase-2 of the Namma Metro project on 3 January 2012. However, there were delays in DPR preparation and hence approval from the Central Government. The estimated cost for Phase-2 was ₹26,405 crore (US$3.7 billion) at 2011-12 price levels with escalation of 5% annually for 5 years. The State Government would contribute ₹9,000 crore (US$1.3 billion). The Union government would share that part of cost escalation due to increase in central levies, while the state and BMRCL would have to bear any other cost escalations. The total project cost for Phase-2 was estimated to reach ₹30,000 crore (US$4.2 billion) at the start of construction itself. In October 2018, Deputy Chief Minister G Parameshwara stated that the cost of Phase-2 would be around ₹32,000 crore (US$4.5 billion). In May-2025, Karnataka government approved further cost escalation by Rs,9,729 crores. Thus, cost for phase-2 was revised at Rs.40,425 crores (US$5.7 billion) After an extension of 3.195km to Challaghatta, Phase 2 spanned a total length of 75.29 km with 13.79km underground, at grade and elevated, and adds 62 stations to the network, of which 12 are underground. Phase-2 included extension of the two Phase-1 lines in both directions, as well as construction of two new lines. The south end of the Green Line will be extended from Yelachenahalli to Silk Institute (previously named Anjanapura) along Kanakapura Road, and the north end from Nagasandra to Madavara (previously named BIEC) on Tumkur Road (NH-4). The east end of the Purple Line would be extended from Baiyappanahalli to Whitefield and the west end from Mysore Road to Kengeri (later extended to Challaghatta). A new, long, fully elevated line from RV Road to Bommasandra would be constructed, passing through
Electronic City. The second new line will be from Kalena Agrahara (previously Gottigere) to Nagawara. The line is mostly underground (), with a elevated section and a at-grade section. There are 18 stations on the line, of which 12 are underground and six are elevated. Karnataka Industrial Areas Development Board (KIADB) was responsible for acquiring land for Phase-2. It was estimated that of land would be required for Phase 2 (including Phase 2A). By April 2017, BMRCL had already spent ₹5000 crore on land acquisition. Construction work began on the south extension of the Green Line from Yelachenahalli to Silk Institute () and the west extension of the Purple Line from Mysore Road to Kengeri () by October 2016. Construction work on the west extension of Purple Line was awarded in two packages for ₹660 crore, while the Green Line south extension was awarded in a single package for ₹508.86 crore. Construction work for the north extension of the Green Line (from Nagasandra to Madavara) and the east extension of the Purple Line (from Baiyyappanahalli to Whitefield) began in July 2017. The north extension was estimated to cost ₹247.41 crore while the east extension () was awarded for ₹1,300 crore (US$180 million). Construction of the yellow line, a new line from Rashtreeya Vidyalaya Road to Bommasandra in 3 packages began post awarding of tenders in November 2017. The first package () was a stretch from Bommasandra to Hosa Road station, including depot entry line to Hebbagodi depot and five Metro stations. The second package was for a stretch from Hosa Road to Bommanahalli (previously HSR Layout). Both packages were awarded for ₹1,750 crore (US$250 million) to Thailand-based ITD Cementation India. Construction of the elevated section of a new pink line between Kalena Agrahara and Tavarekere (previously Swagat Road Cross) stations, estimated to cost ₹575.52 crore (US$81 million) began post tendering in February 2018. The tender includes the construction of the elevated viaduct, 5 stations and car depot line to Kothanur depot.
Underground section BMRC initially floated tenders for the construction of the underground section in four packages during June 2017. However, the tenders were cancelled as all the bids received were far too high (higher by nearly 70%) at Rs.8553.45 crores (US$1.28 billion) when compared to BMRC's estimated total of Rs 5047.56 crores (about US$760 million). The second round of tendering resulted in tenders being awarded to three firms during the March–June period, 2019. One of the firms (
L&T) won two bids. The total awarded tunneling tenders for the underground sections was ₹5,925.95 crores (appx US$812 million). Pre-tunneling construction work and piling for stations began in May 2019 by L&T. Tunnel boring using TBMs began in July 2020 by L&T. Tunnel boring work by the other two contractors (viz.
Afcons & ITD-Cem) was commenced in 2021.
Phase 2A In September 2016, the government announced that a new line connecting Silk Board with K.R. Pura would be included in Phase-2 as Phase-2A of the project. The line would be along the eastern half of Outer Ring Road and is proposed to have 13 stations – Silk Board, HSR Layout, Agara, Ibbalur, Bellandur, Kadubeesanahalli, Kodibisanahalli, Marathahalli, ISRO, Doddanekundi, DRDO Sports Complex, Sarasvathi Nagara (previously Mahadevapura) and K.R. Pura. The cost was estimated to be ₹4202 crores. BMRCL prepared the detailed project report for the proposed line and submitted the DPR to the state government on 28 October 2016. Phase 2A was approved by the State Cabinet on 1 March 2017. The ORR Metro line (Blue line) would have interchange stations with the extended Purple Line at K.R. Pura and with the R V Road – Bommasandra line (Yellow Line) at Silk Board. Tenders for ORR Metro line (east) were called in February 2018 and
IL&FS emerged the lowest bidder for all packages. However, the tenders were quashed due to cash flow problems and bankruptcy proceedings by the firm. A second round of tendering was done in December 2019 and bids were received by multiple firms in March 2020. There are two packages. The first package included 2.84 km of ramps for a flyover at Central Silk board junction in addition to 9.859 km of viaduct with six elevated stations. The second package was for 8.377 km viaduct with seven elevated stations, 1.097 km depot line and a 0.30 km pocket track.
Phase 2B There had been a proposal to build a high speed rail line from MG Road to
Kempegowda International Airport (KIA), at a cost of ₹5,767 crore (US$810 million). This was to be executed by an independent SPV, but later it was decided that BMRC would manage this project and a regular metro line with fewer halts would be built instead of a high speed rail, thus travel time between city to airport would be less. As early as in February 2012, the Central Government had also requested BMRC to start work on the airport link during Phase 2 itself. Following this, in September 2016, suggestions were invited from public to choose any one of nine possible extension routes from existing and proposed metro lines to the airport. The proposed extension routes had an average length of , and cost estimates ranged between ₹4,500 crore and ₹7,000 crore. A extension from Nagawara via Kannur and Bagaluru was the shortest, while the extension from Yeshwanthpur via Yelahanka, Kannur and Bagaluru was the longest of the proposed routes. BMRC received 1,300 responses from the public. A extension of the Kalena Agrahara (previously Gottigere) – Nagawara line via Kannur and Bagaluru to the airport emerged as the most popular choice. Since Bengaluru International Airport Limited (BIAL) forbade underground construction from the southern side of the airport (due to security as it would have to pass beneath the airport's second runway), the shortest route options (i.e. extending the Pink line from Nagawara directly north) were eliminated. An alternate route proceeding north till RK Hegde nagar and then turning west to Jakkur was then explored. However, even this had an obstacle as a high-pressure petroleum pipeline was passing through the originally proposed route. Bangalore Development Minister
K. J. George announced on 12 May 2017 that the government had finalized the Nagawara-Ramakrishna Hegde Nagar-Jakkur-Yelahanka route to the airport. On 10 January 2019, the State Cabinet approved a change in alignment for the proposed metro line to the airport. The new line would begin at Krishnarajapura (K.R. Pura) and be aligned along the northern part of ORR (Outer Ring Road), passing Nagawara, Hebbal, and Jakkur before heading towards the airport along Ballari road. The line would be long, about longer than the route previously proposed. It is estimated to cost ₹10,584 crore (US$1.5 billion) almost twice as much as the previous route's estimate of ₹5,950 crore (US$830 million). The Union Cabinet cleared two much awaited and long delayed lines of the Bengaluru Metro's Phase 2A and 2B on 20 April 2021. Phase 2A and Phase 2B lines total a distance of 58.19 km and were approved at a cost of Rs.14,788 crore. The projected ridership on both these lines in 2026 is estimated at 7.7 lakhs. Construction of the airport line is expected to begin by October 2021.
Phase 2, 2A, and 2B lines and sections Phase 2 originally involved extending four reaches of the two lines in all directions and two new lines; Yellow and Pink. The ORR-East Line was later included as Phase 2A followed by the Airport Line (as a continuation of the ORR-East Line) as Phase 2B. The line was later named the
Blue Line. Construction of Phase 2A has been divided into two (elevated section) packages, while the construction of Phase 2B has been divided into three (elevated section) packages. Airport stations have not been included with tenders as they will likely be built by BIAL. == Network ==