Project Case Study

Bangkok to Chiang Mai Northern Line, Thailand


State Railway of Thailand (SRT)


Due for completion 2023



Fastclip Baseplates

Customer challenge

The Northern Line railway runs for 751 kilometres through Thailand, from Bangkok station in the centre of the country to Chiang Mai in the north.

The State Railway of Thailand (SRT) is currently undertaking a major track doubling project to change railways from single (bi-directional) to double-track lines. This presented an opportunity to tackle an ongoing issue with flooding on a stretch of the Northern Line from Lopburi to Pak Nam Pho, where traditional ballasted tracks are regularly underwater or washed away during the rainy season from June to November.

The decision was made to build an elevated structure – a vast viaduct – stretching 19 km through flood zones and rice fields. A high-quality fastening system was needed for the ballastless track and in 2019 SRT awarded Pandrol the contract to supply Fastclip baseplates for the full length of the viaduct.

Pandrol solution

Pandrol’s Fastclip baseplates offer a captive rail fastening system that is ideal for ballastless track applications like the viaduct. The assembly combines safety, durability and the latest technology in a compact package that is reliable and easy to build and maintain.

The baseplates supplied to SRT were configured to meet the specific needs of the viaduct in terms of stiffness, vertical and lateral adjustment, clamping force and longitudinal restraint. The stiffness built into the fastening assembly, which keeps rolling noise low, means that it is an ideal choice for passenger railways like the Northern Line. Making vertical and lateral adjustments on site proved quick and easy, with no need to disassemble the fastening. And the availability of a zero longitudinal restraint (ZLR) version of the fastening for installation at expansion joints proved particularly useful for this viaduct application.

From the outset, the project was a great One Pandrol effort, with our local engineers in Thailand providing on-site support and drawing on the expertise of Pandrol worldwide.

A factory in Ayutthaya, close to the construction site, was responsible for manufacturing the concrete sleepers for the viaduct and we worked closely with engineers there to ensure the sleepers would be compatible with Fastclip baseplates. In total, 62,691 sleepers and 125,382 baseplates (including around 6,000 of the ZLR conversion) will be delivered to site, and pre-assembled for speed, efficiency and accuracy.

Track laying started in 2022 and our support engineers worked closely with contractors and subcontractors – Unique, Sinohydro, SEC Asia Trackwork and Trans Thai Railway – to ensure track build went smoothly. As well as providing expertise and advice as the baseplate assemblies were installed, we trained contractors and suggested innovations to improve efficiency, such as the use of an intelligent clipping machine from Pandrol’s IQ range that can install up to 20 baseplates per minute. As well as being an advantage for track construction, this speed of clipping and unclipping is particularly useful for rail neutralisation in Thailand, which needs to take place within short time windows at specific temperature ranges.

As the track laying project approaches completion, Pandrol will also be supplying welding products and services.

Adding value

“It has been invaluable to draw on Pandrol’s local and global support throughout this complex, challenging project. The team’s expertise, efficiency and speed have been exemplary.”

Wittaya Sukontha, Managing Director, SEC Asia Trackwork (Thailand)


The new track will accommodate more trains, reduce travel times, minimise disruption due to poor weather, and reduce the cost of logistics.

When the viaduct is complete, it will be the longest elevated section of track on the State Railway of Thailand – and it will be fitted entirely with Fastclip baseplates.

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