Summary

Sleepers on a railway bridge hold the rails to gauge. They also transfer train loads into the bridge structure. However, traditional timber sleepers deteriorate with age and weather. For this reason, many railways are turning to more durable materials. This article first explains the principles using technical sources. It then presents a case study: the replacement of timber sleepers with steel sleepers on 14 railway bridges by BIS (Bridge and Infrastructure Solution), part of WCE’s CTE business unit.

1. What Do Sleepers Do on a Bridge?

On an open-deck steel bridge, sleepers sit directly on the bridge girders. There is no ballast to spread the load. As a result, the sleepers carry the full train load and must be strong enough to do so. In fact, testing by the Transportation Technology Center (TTCI) found that not all timber bridge ties could withstand the recommended design load [1].

2. Key Principles

2.1 Problems with Timber Sleepers

A review of sleeper failures identifies three key failure mechanisms for timber sleepers: fungal decay, end splitting, and termite attack. These problems lead to early replacement and high maintenance costs [2]. For example, researchers report that timber transoms on an Australian bridge need renewal every 10–20 years. The main causes are humidity, salt spray, and dynamic loading [3].

2.2 Alternative Materials and Life Cycle Cost

Researchers have studied alternatives to timber on bridges. These include steel-concrete composite and fiber composite systems, with design lives of over 50 years [3]. In addition, studies have analyzed life cycle cost across manufacturing, installation, maintenance, and end-of-life. One study notes that maintenance makes up 25–35% of annual operating costs on Australian railway networks. Therefore, material choice strongly affects long-term cost [4].

2.3 Advantages of Steel Sleepers

According to a steel sleeper manufacturer, steel sleepers typically last around 50 years. They are also light enough to transport in larger quantities. Finally, they are fully recyclable at end of life [5]. Note that this is commercial information. Actual service life depends on site conditions and maintenance.

3. Case Study: Steel Sleepers on 14 Railway Bridges by BIS / CTE

• Scope: Supply or manufacture of steel sleepers and replacement of timber sleepers on 14 steel railway bridges, 486 sleepers in total
• Example bridges: DP type 12 m, DG type 7×6 m, and TT type 25 m, each 100% installed
• Client: State railway agency
• Location: Southern Line, Thailand
• Duration: 30 October 2025 – 26 July 2026 (about 9 months)
• Progress: Plan 100% / Actual 100%, with 100% of work verified

The cover image shows installed steel sleepers in three bridge settings. From left to right, you can see a steel truss bridge, a concrete bridge approach, and a bridge over a pond. Note that the timber sleepers in the foreground of the left image sit on the embankment before the bridge. They were outside this scope. We edited all images with AI so that no individuals or clients can be identified.

4. Observations

• Work on the bridges of an operating railway must fit around available track access.
• In addition, this job was spread across many bridges in several areas. Therefore, verifying 100% of the work at every bridge was a key step before handover.

5. WCE Services

BIS (Bridge and Infrastructure Solution), part of the CTE business unit, provides bridge and infrastructure engineering, including railway work.

To discuss your project: +66 65-937-6283 | international@wce.co.th | www.wce.co.th
We engineer your success.

References

(Accessed 2 Oct 2026)
[1] Transportation Technology Center, Inc. (October 2011). Benchmark Testing of Timber Open Deck Bridge Ties. Technology Digest TD-11-036. https://www.mxvrail.com/wp-content/uploads/2023/01/TD11-036.pdf
[2] Ferdous, W., Manalo, A., Aravinthan, T. & Remennikov, A. (2014). Review of failures of railway sleepers and their consequences. Proceedings of the 1st International Conference on Infrastructure Failures and Consequences (ICFC 2014). https://research.usq.edu.au/item/q28x0/review-of-failures-of-railway-sleepers-and-its-consequences
[3] Mirza, O. & Kaewunruen, S. (2018). Resilience and Robustness of Composite Steel and Precast Concrete Track Slabs Exposed to Train Derailments. Frontiers in Built Environment, 4. https://doi.org/10.3389/fbuil.2018.00060
[4] Senaratne, S., Mirza, O., Dekruif, T. & Camille, C. (2020). Life cycle cost analysis of alternative railway track support material: a case study of the Sydney Harbour Bridge. Journal of Cleaner Production, 276, 124258. https://doi.org/10.1016/j.jclepro.2020.124258
[5] British Steel. Steel Sleepers (manufacturer product information). https://www.britishsteel.co.uk/what-we-do/rail/steel-sleepers/