The "loading gauge" of the EU rail network refers to the maximum height and width that a train and its load can be to ensure it clears bridges, tunnels, and platforms. While there is no single "universal" gauge for the entire continent, the most common standard used for international interoperability is the UIC GC gauge, which allows for a maximum width of 3.15 meters and a height of up to 4.65 meters. This is significantly larger than the standard UK loading gauge (W6A), which is why many continental European trains cannot run on British tracks. Most new high-speed lines in the EU are built to the GC standard to accommodate larger double-decker trains and high-volume freight. However, older parts of the network, particularly in Eastern Europe or the Iberian Peninsula, may have different restrictions. It is important to distinguish this from the "Track Gauge," which is the distance between the rails; in the EU, the standard track gauge is 1,435 mm (4 ft 8.5 in). In 2026, the EU's "Fourth Railway Package" continues to push for the harmonization of these loading gauges to create a truly borderless European rail area.