Purple Line (Bangkok)

The MRT Purple line (รถไฟฟ้ามหานคร สายสีม่วง) or MRT Chalong Ratchatham line (รถไฟฟ้ามหานคร สายฉลองรัชธรรม) is Bangkok's fifth rapid transit line, following the Sukhumvit Line, Silom Line, MRT Blue Line, and Airport Rail Link. The line is 23 km long, serving the north-western area of Bangkok running from Tao Poon to Klong Bang Phai in Nonthaburi Province.

The line opened on 6 August 2016. It is the second line of MRT system and is operated by BEM under a concession contract. Daily ridership is 70,000.

A 23.63 km, 17 station southern extension of the line consisting of a 14.3 km underground section and a 9.3 km elevated section commenced construction in August 2022. The cost of the southern extension is 82 billion baht and it is planned to open at the end of 2027. By the end of May 2023, construction had progressed to 11.50%.

Route alignment


The Purple line starts from Khlong Bang Phai station in Bang Bua Thong District. The line travels south along Kanchanaphisek Road before turning eastward near Central WestGate, onto Rattanathibet Road. It continues along Rattanathibet Road, passing through a large residential area in Bang Yai District and crosses the Chao Phraya River on a bridge parallel to the Phra Nang Klao Bridge and runs towards Nonthaburi Civic Center station. The line then turns southward onto Tiwanon Road, passing the Ministry of Public Health and turns southeast onto Krung Thep-Nonthaburi Road, entering Yaek Tiwanon station. The line then enters Bangkok city limits at Bang Sue district and passes Bang Son station before terminating at the upper platforms of Tao Poon station, with a total length of 23 km, serving 16 stations.

History
Officially named the Chalong Ratchadham Line (สายฉลองรัชธรรม) – "To Celebrate the Great King's Reign with Righteousness" – but informally known as the "Purple Line", the rapid transit line provides a north–western corridor in Bangkok's Mass Rapid Transit Master Plan. The line also incorporated an extension of the Blue Line from nearby Bang Sue station to Tao Poon Station.

This line was created from the adjustment of the 1994 mass transit rail system master plan, which connected the original extension of the Blue Line from Tao Poon to Bang Yai, while the original Purple Line would have run from the National Library to Tao Poon and the original Orange Line from Samsen (National Library) to Rat Burana, becoming a new line designated as the Purple Line, included in the master plan of the Office of Transport and Traffic Policy and Planning (OTP) for the first time in 2004. Five years later, the line's construction began.

Construction was divided into six contracts, three of them for civil works. The contracts were signed from late 2009 to early 2010 and completion was originally scheduled for the end of 2014. The third contract included construction of four park and ride buildings at the Khlong Bang Phai, Sam Yaek Bang Yai, Bang Rak Noi Tha It, and Yaek Nonthaburi 1 stations. On 31 March 2017, the fifth contract was effectively terminated and became part of a new Blue Line concession agreement.

The 2011 Thailand floods delayed the construction of the line for nearly 1 year. In June 2013, five people were injured when six beams fell onto vehicles below Tao Poon station. In July 2014, the civil work was 94 percent complete; in October 2014, civil work was stated to be 99% complete.

The line opened on August 6, 2016, when His Majesty King Bhumibol Adulyadej graciously appointed Her Royal Highness Princess Maha Chakri Sirindhorn to represent him in presiding over the opening ceremony and officially pressing the button to open the electric train system. However, the MRT Blue Line extension to Tao poon was delayed, so when it opened the Purple Line couldn't interchange with the Blue line as planned. This resulted in low line usage. Even with a reduced fare, the line only attracted about 22,000 passengers daily compared to a goal of 100,000. A shuttle bus service was in operation between Tao Poon MRT station and Bang Sue MRT station to connect with the Blue Line. When the Blue line extension finally opened a year later, on 11 August 2017, ridership significantly increased. In 2019, daily ridership was 70,000.

Rolling stock
In November 2013, BEM contracted with Marubeni Corp, Toshiba Corp, and East Japan Railway Company to install E&S systems, supply 21 three-car trains (total of 63 cars) rolling stock, and provide maintenance for 10 years as part of a contract worth 12.6 billion baht. East Japan Railway train manufacturing subsidiary J-TREC built them in Yokohama with the first sets delivered in early 2016. The trains are owned by the MRTA which paid for the rolling stock at BEMs request. The southern extension will acquire 17 additional trains, along with the current ones, to create a total of 38 trains.

In total, line is service by 21 three-car trains. Trains are powered by 750 V DC via third rail system, are air-conditioned and capable of traveling at up to 80 km/h.

Operation
The 16-station Purple Line runs from Khlong Bang Phai to Tao Poon and has a carrying capacity of 30,000 people in each direction per hour. The line operates daily from 06:00-24:00 with an interval of under 6 minutes during peak hours and 9 minutes during off-peak hours. All stations on the line are equipped with platform screen doors. Stations are built to accommodate six-car trains, but only three-car trains are used. The line has 1 depot near Khlong Bang Phai station

The MRTA has proposed to BEM to introduce multi-trip package fares to reduce prices which follows an earlier proposal by the Department of Railways to offer 40% discounts during off peak travel.

Ridership
When the Purple line first opened daily ridership was only 22,000 compared to projected numbers of 100,000. After the opening of the Blue Line extension to Tao Poon 1 year later in August 2017, daily average ridership increased significantly from 33,000 to 50,000.

In August 2018, the MRTA Deputy Governor stated that daily ridership had increased to 60,000 each weekday. By late 2019, this had increased to 70,000. In 2023 the purple line saw an average of 50385 passengers per day.

Southern extension
As the northern section of the Purple line was built first, the 2nd phase southern extension of the Purple Line south from Tao Poon via Rattanakosin - Bangkok's old town - to Rat Burana would fully complete the line. The length of the southern extension is 23.63 km (14.29 km underground, 9.34 km elevated with 17 stations - ten underground and seven elevated).

The Thai Cabinet was expected to approve the tender in mid 2017 with a tender then to be issued in the second half of 2017. On 25 July 2017, Cabinet approval was given, but the tender was then delayed until 2018. By December 2018, a tender had still not been issued and was further delayed. In August 2019, subject to final land acquisition, a March 2020 tender was planned. In mid 2020, the Ministry of Transport still aimed for a tendering process within 2020 despite COVID-19 related delays. The MRTA then expected to issue a tender in February 2021. and if construction had begun in 2021, the extension was projected to enter service sometime in 2027. However, the tender was delayed yet again and subsequently cancelled in August 2021 until it was finally issued in November 2021.

Construction contracts were signed on 11 March 2022 with a 2005 construction period for an ambitious planned 2027 opening date.

Construction progress
Contactors were issued with a Notice to Proceed on 25 April 2022 giving them access to sites along the route with actual construction planned to begin from August 2022. Construction began in early August for two contract sections, 3 & 4. Some 410 lots and 500 buildings will need to be appropriated to build the extension and as of May 2022 many of them were still to be surveyed.

Construction progress was at 3.45% complete at the end of September 2022. By the end of November 2022, construction progress was at 4.30%. At the end of February 2023, construction had progressed to 7.73%.

By the end of May 2023, construction had progressed to 11.50%.

Construction contracts
Construction is divided into 7 contracts.

Contract 1 is for 3.8 km underground and 4 underground stations from Tao Poon interchange station to National Library station won by CKST Joint Venture comprising CH Karnchang and Sino-Thai for 19.4 billion baht.

Contract 2 is for 2.4 km underground and 2 underground stations from National Library station to Phan Fah station won by CKST Joint Venture comprising CH Karnchang and Sino-Thai for 15.8 billion baht.

Contract 3 is for 3.1 km underground and 2 underground stations from Phan Fah station to Memorial Bridge station won by ITD-NWR Joint Venture of Italian‑Thai and Nawarat Patanakarn for 15.1billion baht,

Contract 4 is 4.1 km underground and 3 underground stations from Memorial Bridge station to Dao Khanong station won by Unique Engineering for 14.9 billion baht.

Contract 5 is 9 km elevated and 7 elevated stations from Dao Khanong station to Krui Nai station won by ITD for 13 billion baht.

Contract 6 is for track & electrical won by ITD for 3.5 billion baht.

Contract 7 is for the procurement of 17 additional trains.