How Network Rail Protects Steel Infrastructure with Protective Coatings
Switch rail coating in preparation for hot weather by Network Rail technicians and a COSS (Controller of Site Safety). The work needs to be carried out quickly and efficiently to minimise disruption to train operations.
Its an intriguing question, if you’re interested in corrosion prevention and protection, like we are here at D&D Coatings. With so much steel work playing an important role in the nations rail infrastructure, how on earth do Network Rail stop it from rusting. After-all it owns and maintains 20,000 miles of track, 20 stations, 30,000 bridges, tunnels, viaducts, signalling, switches and level crossings. The simple answer is, protective coatings. But which coatings do they use and in what system configurations are they applied? Read on to find out.
The Forth Bridge in Scotland, thanks to new coating systems and improved application methods now needs to be repainted every 25 years. Until recently this was a continuous never ending task.
Who does all the work?
Whether you travel by rail or not, you’ll have seen the people in bright orange suits busy working on the railways. These people are Network Rail engineers. Many are contractors, companies like Murphy, Balfour Beatty but most are Network Rails own engineers.
Network Rail contractors Murphy, carry out track upgrade work.
Engineers are responsible for a wide range of infrastructure maintenance activities. These include routine inspection of tracks, bridges, gantries, switches, signals, and power supplies.
Painting technician applying intermediate build coat to steel bridge underside supporting girders and braces.
Preventative work such as drainage maintenance, application of protective coatings, ventilation upkeep, and structural repairs all play a critical role in ensuring the safety and reliability of Britain’s railways.
In this article, however, we will focus specifically on the role of protective coatings in railway infrastructure maintenance.
Network Rail painting contractors
Companies involved specifically with painting contracts include SSL Environmental, Bagnalls and Story Contracting. They are all responsible for maintaining the UK’s railway infrastructure. This infrastructure relies heavily on steel and much of it needs protective coatings to keep it operating safely over long periods of time.
…white paint is even applied to tracks to stop them from buckling in hot weather!
Refurbishment work begins to repair the heavily corroded Barmouth Bridge in west Wales, the £30m project took four years to complete.
Where are protective coatings used in rail infrastructure?
Across the UK’s rail infrastructure protective coatings are used extensively. They are applied to shield components from corrosion, fatigue, wear, and environmental factors. These coatings are applied to a wide range of surfaces, including bridges, footbridges, trackside structures such signals and overhead line equipment. In extreme weather white paint is even applied to tracks to stop them from buckling!
What type of coatings are used?
Network Rail-approved coatings manufacturers include Jotun, Sherwin-Williams, PPG, Hempel, and AkzoNobel International, as well as a number of smaller manufacturers. All products must comply with stringent standards. These include requirements such as low-temperature curing capabilities, surface humidity tolerance, and resistance to aggressive atmospheric conditions.
Network Rail engineer carrying out detailed painting work under large high level steel railway bridge inside self-contained mobile coating rig.
Coatings intended for more decorative applications, such as fast-drying acrylic urethanes are employed where appropriate. All Network Rail coating systems must provide consistent reliability and offer long-lasting guarantees.
Shrink wrapped sections of scaffolding used to contain blasting debris and paint spill during refurbishment of a steel railway viaduct.
Commonly used coatings
Zinc-Rich Primers Applied as a base layer, these primers provide sacrificial corrosion protection by acting as a galvanic barrier.
Epoxy Coatings These coatings form a super robust, chemical-resistant barrier that shields steel from moisture, chemical attack, and abrasions.
Polyurethane or Acrylic Topcoats Provide UV resistance, durability, and a visually appealing finish that also add an extra layer of protection against weathering.
Single coat systems
Single-coat paint systems are used by Network Rail when fast application times and minimal disruption is vital. Unlike traditional multi-coat systems, single coat systems are intended to offer weather resistance or corrosion protection and in just one application. Single-coat systems are typically employed when access is difficult and work windows are short, such as in live rail environments or over operational lines.
Steel rail bridge girders paint spray work carried out by Network Rail technicians.
1. Single coat
Purpose: Fast turnaround, weather protection for rails, touch-up and maintenance work. Products: Sherwin-Williams Dura-Plate 301 or Jotun Jotamastic 87
Two coat systems
Two-coat paint systems are commonly used to provide durable, long-term protection against corrosion, environmental exposure, and mechanical wear. These systems are critical for assets like bridges, gantries, masts, and signal structures. Typically, the two coats consist of an epoxy primer and second finish coat.
1. Epoxy Primer
Purpose: The first layer is a high-performance primer designed to bond tightly to the prepared steel surface. The primer must also resist moisture, temperature changes, and mechanical damage. Products: Zinc Epoxy Primers (e.g., Sherwin-Williams Macropoxy, Jotun Barrier primers)
2. Second Coat (Finish Coat)
Purpose: Protective and decorative topcoat, UV resistance, chemical resistance and colour stability, as well as the desired colour and aesthetic finish. Products: Resistex C137V2 Special Finish, Hardtop HB / XP, Hardtop Optima / CA / XP / Flexi, Hardtop Flexi / HB / XP, International Interthane 990.
Three coat systems
Network Rail often uses a three-coat paint system involving an epoxy primer, an intermediate coat, and a polyurethane topcoat for steel structures, ensuring long-lasting corrosion protection and durability. Here are more details about each coat:
1. Epoxy Primer
Purpose: Provides a strong, high-performance durable base primer for the subsequent coats designed to bond tightly to the prepared steel surface and protects against corrosion. Products: Epigrip C401 Epoxy MIO, Jotamastic 80 Alu, Penguard Express ZP, International Intergard 214.
2. Intermediate Coat (Build Coat)
Purpose: Builds up the overall coating thickness and provides additional protection. Products: Epigrip C402V2 Zinc Phosphate Primer/Buildcoat, Jotamastic 80 Colour, Penguard Express MIO, Jotamastic 90 Colour, International Intercure 384 MIO.
3. Third Coat/Topcoat (Finish Coat)
Purpose: Provides the final protective decorative topcoat layer, as well as the desired colour and aesthetic finish. Products: Resistex C137V2 Special Finish, Hardtop HB / XP, Hardtop Optima / CA / XP / Flexi, Hardtop Flexi / HB / XP, International Interthane 990.
How are coatings applied?
Network Rail and their subcontractors use a variety of painting equipment. From good old fashioned brushes and rollers to specialised spray applicators. Scaffolding, shrink wrap scaffolding encapsulation and self-contained mobile coating rigs are used during infrastructure coating projects. These are primarily used on steelwork coating for bridges, gantries, pole-mounted distribution transformers, signalling, roof supports, metal railings and many other critical rail network components.
Abrasive Blasting Used to remove old paint layers before applying new coatings, as seen in the Forth Bridge painting project.
Brushes and Rollers Used for applying paint to various surfaces, as seen in Network Rail’s preparation for summer.
Scaffolding and Screening Used to create controlled painting environments, especially for large structures like bridges. This helps capture debris and provides a protected area for applying and curing coatings.
Rail-mounted Cherry Pickers Rail-mounted cherry pickers, also known as Mobile Elevated Work Platforms (MEWPs), are specialised vehicles used for accessing elevated areas on British railways. Designed to travel quickly and easily on railway tracks they are equipped with a boom lift to access heights, ideal for rapid coating tasks.
Network Rail workers pose for a picture at the completion of the four year refurbishment project to restore the once heavily corroded steel rail crossing.
Conclusion
So there you have it, a glimpse into the vital role protective coatings play in the world of railway infrastructure. It’s remarkable to think that a protective layer of paint, often less than a millimetre thick, serves as such a powerful shield. A shield safeguarding the reliability, safety, and longevity of Britain’s railways.
Next time you catch sight of engineers in those orange boiler suits, busy working away with brushes, rollers, or spray guns and all sorts of other equipment, take a moment to appreciate the critical work they’re doing. Every coat of paint keeps the nation moving safely, efficiently and for generations to come.
