Calton Road Rail Bridge

Originally built in 1896, the Calton Road rail bridge plays a vital role in Edinburgh’s transport network, carrying trains in and out of Waverley Station—one of Scotland’s busiest rail hubs. In January 2022, Network Rail launched a £1.7 million refurbishment project to repair and re-paint the bridge, protecting the structure from long-term weathering. A critical part of this work was ensuring the paint application met stringent quality standards, as any failure in the finish due to poor environmental conditions would require a costly and disruptive rework, especially problematic in such a high-traffic city centre location.

Challenge

The contractor responsible for the re-painting brought in Polygon to manage temperature and humidity throughout the project. The brief required more than just climate control; it called for a solution that was reliable, energy-efficient, and environmentally conscious, with minimal disruption to the surrounding public. Site access was restricted due to the bridge’s continued use by both vehicles and pedestrians, and energy availability was limited, ruling out standard high-power equipment. The challenge was to create and maintain precise atmospheric conditions without compromising on performance, sustainability, or project timelines.

Solution

Polygon began by conducting a detailed environmental assessment, identifying all the factors that could affect the painting process. Using this data, a custom climate-control strategy was developed. Rather than using large, static box heaters, Polygon deployed compact, mobile heating units that offered flexibility on-site without sacrificing output. This adaptability was crucial for working around site constraints. To accommodate the restricted power supply, the team utilised 110V equipment to deliver the necessary heat without needing a three-phase connection. A carefully balanced system of heating and dehumidification ensured the air remained within optimal temperature and humidity ranges throughout the re-painting process.

Results

The tailored solution provided consistent climate conditions essential for a high-quality, durable paint finish, helping the project stay on schedule and budget. Polygon’s approach not only minimised energy consumption and environmental impact but also allowed the bridge works to proceed with minimal disruption to the public. The success of this low-impact, high-performance climate control plan ensured that Network Rail’s investment in the Calton Road rail bridge was protected, with no need for costly rework or delays.