ballastless

Ballastless refers to railway track systems that do not rely on a ballast layer of crushed stone to support and align rails. Instead, rails are fixed to a rigid or semi-rigid base such as a concrete slab or a multifunctional rail deck, which provides structural support, load distribution, and drainage. Ballastless track is common in slab track configurations and is contrasted with traditional ballasted track, where ballast layers allow vertical and lateral adjustments.

In ballastless systems, a concrete slab acts as the support framework. Rail fasteners directly anchor rails into the slab or into embedded steel elements. A sub-base and drainage system is usually provided, sometimes with elastic or resilient layers to reduce vibration. Variants include embedded slab track, slab with trough, and modular systems with replaceable tiles. Maintenance focuses on resurfacing and joint sealing, track geometry integrity, and occasionally milling of surface cracks.

Ballastless track offers high geometric stability at elevated speeds, improved drainage, and lower risk of ballast degradation, weeds, and maintenance of ballast. It can reduce vibration and noise with proper elastomeric or resilient fasteners. However, initial cost is higher, installation is complex, and repairs can be invasive; it is less adaptable to track geometry changes, and thermal expansion can present design challenges. Longevity is highly dependent on design quality and traffic.

First developed in the mid-to-late 20th century, ballastless track has become common on high-speed rail corridors and modern urban rail systems. It is widely used in Europe, East Asia, and other regions for new lines and upgrade projects where precise alignment, reduced maintenance, and durable service are priorities.