The Purple Line is a part of the Namma Metro rail system for the city of Bengaluru, Karnataka, India.

[1] As of 2023, the line is 43.49 km (27.02 mi) long and spans 37 stations from Challaghatta in the southwest to Whitefield (Kadugodi) to the east.

The Line passes through many prime activity centers of the city including Whitefield, Krishnarajapura, MG Road, Vidhana Soudha, Vijayanagar, Rajarajeshwari Nagar, Kengeri.

[4] Civil construction work on Phase I of the line began on 15 April 2007 and was originally scheduled to be completed in 5 years.

Difficult tunnel boring conditions through a mixed geology with hard rock caused major delays.

[9][10] The first stretch of Purple Line (Reach 1, fully elevated) between Baiyyappanahalli and Mahatma Gandhi Road was inaugurated on 20 October 2011.

These two sections operated independently until the final section, the underground stretch between Mahatma Gandhi Road and City Railway station was opened on 30 April 2016, thus linking the previously opened stretches and completing Phase I for the Purple Line.

The Federation of Karnataka Chambers of Commerce and Industry (FKCCI) had estimated that interest payment alone would be ₹2 crore (US$230,000).

[20] Underground stations (City railway station, Sir M Visvesvaraya, Vidhana Soudha and Cubbon Park) were built by cut-and-cover method which required 10,000 controlled blasts using 50,000 kg of explosives of 125 gm gel nitrate capsules due to hard granite rock.

After missing several deadlines, it was finally opened to the public on 20 October 2011 at 4 pm IST by Union Urban Development Minister Kamal Nath.

[32] Reach 2 received clearance to start services (from Satish Kumar Mittal, Commissioner for Metro Rail Safety - CMRS) on 21 September 2015.

[36] The Commissioner for Railway Safety (CRS) granted clearance to begin operations on the underground section in the first week of April 2016.

[39][40] Trains ran until 10 pm on the opening day, making 115 trips and transporting about 93,500 passengers, earning BMRCL a revenue of ₹35 lakh (US$40,000).

On the first two days of operation, after opening of the underground section, BMRCL collected over ₹7 million in revenues from the Purple Line.

[43][44] In October 2016, the BMRCL began civil work on the west extension of the Purple Line from Mysore Road to Kengeri (8.81 km), later extended to Challaghatta.

[46] IL&FS Engineering Construction Company bagged the contract for Reach 2A of 3.94 km (Mysore Road to Pattanagere stretch) that includes four stations at ₹ 327 crore.

[47] BMRCL floated tenders for the construction of the 15.5-km elevated stretch from Baiyyappanahalli to Whitefield railway station in December 2016.

Reach 1B, the 7.21 km section from Kundalahalli to Whitefield, includes seven new stations and is estimated to cost ₹ 666.12 crore.

Italian-Thai Development Public Company Limited (ITD) was awarded the contracts for both packages, for a sum of ₹1,300 crore (US$150 million), in May 2017.

It includes the Urbalis 200 Automatic Train Control system which will ensure optimal safety, flexible operations and heightened passenger comfort.

[63][64] The integrated control centre at Baiyyappanahalli has direct communication with trains and stations are CCTV fitted with visual and audio service information.

[66] From 7 November 2016, Purple Line trains began running at an interval of every 4 minutes between 9:10 am and 9:58 am to handle rising passenger traffic during morning peak hour.

However, the Research Design and Standards Organization (RDSO) fixed the speed at which trains are allowed to commercially operate at 67.50 km/h on straight sections, 35 km/h on curves, and 45 km/h in stations.

As the inter-station distance on the line is about 1 km, the trains have limited time to run at higher speeds.

The tunnels are equipped with walkways to enable passengers to disembark from a train and walk to the nearest station in case of a technical failure.

All stations were built with flame retardant materials, and also have 100,000 litres of water stored on-site for use in case of a fire.