# Line 4 (Chennai Metro)

The Orange Line or Line 4 is one of the planned lines of Chennai Metro. It is part of the second phase of the project and the under construction line stretches from Lighthouse to Poonamallee Bypass. The line will consist of 27 stations, out of which nine will be underground and 18 will be at grade or elevated.

## Planning and construction
### Phase II

The construction of the first phase of Chennai Metro started in June 2009. Commercial operations started on the green line in June 2015. On 10 February 2019, the extension of blue line was opened, completing the first phase of the metro.
In July 2016, Government of Tamil Nadu announced that the second phase would have three lines totaling 104 km (65 mi) in length with 104 stations. Two corridors would extend from Madhavaram connecting with Siruseri and Sholinganallur respectively with the third corridor connecting Koyambedu with Lighthouse. In July 2017, the state government announced an extension in Phase II, involving an extension of line four from Lighthouse up to Poonamallee with an intersection with the Madhavaram–Sholinganallur line at Alwarthirunagar. The line will extend to 26.1 km (16.2 mi) with 16 km (9.9 mi) elevated and 10.1 km (6.3 mi) underground. It will consist of 30 stations including 12 undergrounds stations. The stations for the second phase were designed to be smaller than the existing stations operational in the first phase.
On 20 November 2020, foundation stone for the second phase was laid and construction commenced. In November 2022, Alstom was awarded the contract to supply metro coaches for the phase II expansion. In May 2023, CMRL announced a revised plan for the second phase revising the station count on the fourth line to 27. As per the final plan, the fourth line will extend for 26.1 km (16.2 mi).
Chennai Metro - Phase II :
| Line Name | Terminals | Terminals | Length (km) | Stations | Status |
| Orange Line | Poonamallee Bypass | Lighthouse | 26.1 | 27 | Under construction |
The second phase is estimated to cost ₹63,246 crore (US$7.2 billion) of which initially ₹4,710 crore (US$540 million) was loaned by JICA. On 14 February 2021, Prime Minister of India announced that the government has set aside ₹63,000 crore (US$7.2 billion) for the construction of phase II and further extension.

### Phase II extension

In 2022, the state government proposed an extension plan for the fourth line from Poonamalee to Parandur, covering an approximate 43.6 km (27.1 mi). In early 2024, feasibility report was submitted by CMRL for the proposed expansion of the line, green lighting the same.
Chennai Metro - Phase II Extension :
| Line | Terminals | Terminals | Length | Stations | Status |
| Orange Line | Poonamallee | Parandur | 43.6 km (27.1 mi) | 19 | Planned |

## Stations

Orange Line :
| S.No | Station Name | Station Name | Connections | Layout | Opened |
| S.No | English | Tamil | Connections | Layout | Opened |
| 1 | Lighthouse | கலங்கரை விளக்கம் | | Underground | Under construction |
| 2 | Kutchery Road | கச்சேரி சாலை | | Underground | Under construction |
| 3 | Thirumayilai | திருமயிலை | Chennai MRTS (Thirumayilai ) Purple Line | Underground | Under construction |
| 4 | Alwarpet | ஆழ்வார்பேட்டை | | Underground | Under construction |
| 5 | Bharathidasan Road | பாரதிதாசன் சாலை | | Underground | Under construction |
| 6 | Boat Club | படகு குழாம் | | Underground | Under construction |
| 7 | Nandanam | நந்தனம் | Blue Line | Underground | 25 May 2018 |
| 8 | Panagal Park | பனகல் பூங்கா | | Underground | Under construction |
| 9 | Kodambakkam | கோடம்பாக்கம் | South Line, Chennai Suburban (Kodambakkam) | Underground | Under construction |
| 10 | Power House | பவர் ஹவுஸ் | | Elevated | Under construction |
| 11 | Vadapalani | வடபழனி | Green Line | Elevated | 29 June 2015 |
| 12 | Saligramam | சாலிகிராமம் | | Elevated | Under construction |
| 13 | Saligramam Ware House | சாலிகிராமம் கிடங்கு | | Elevated | Under construction |
| 14 | Alwarthiru Nagar | ஆழ்வார் திருநகர் | Red Line | Elevated | Under construction |
| 15 | Valasaravakkam | வளசரவாக்கம் | Red Line | Elevated | Under construction |
| 16 | Karambakkam | காரம்பாக்கம் | Red Line | Elevated | Under construction |
| 17 | Alapakkam Junction | ஆலப்பாக்கம் சந்திப்பு | Red Line | Elevated | Under construction |
| 18 | Porur Junction | போரூர் சந்திப்பு | | Elevated | Under construction |
| 19 | Porur Bypass | போரூர் புறவழிச்சாலை | | Elevated | Under construction |
| 20 | Thelliyaragaram | தெள்ளியார் அகரம் | | Elevated | Under construction |
| 21 | Iyyapanthangal | ஐயப்பன்தாங்கல் | Iyyapanthangal Bus Stand | Elevated | Under construction |
| 22 | Kattupakkam | காட்டுப்பாக்கம் | | Elevated | Under construction |
| 23 | Kumananchavadi | குமணன்சாவடி | | Elevated | Under construction |
| 24 | Karayanchavadi | கரையான்சாவடி | | Elevated | Under construction |
| 25 | Mullaithottam | முல்லைத்தோட்டம் | | Elevated | Under construction |
| 26 | Poonamallee | பூவிருந்தவல்லி | Poonamallee Bus Terminus | Elevated | Under construction |
| 27 | Poonamallee Depot | பூவிருந்தவல்லி பணிமனை | | Elevated | Under construction |
| 28 | Poonamallee Bypass | பூவிருந்தவல்லி புறவழிச்சாலை | | Elevated | Under construction |
$^§$ under construction