The familiar red oval of a running track is a globally recognized symbol of athletic competition. The modern track is a highly engineered, multi-layered system designed to optimize performance, safety, and durability. Its composition has evolved into a sophisticated synthetic structure that provides consistent conditions for athletes regardless of the weather. Understanding what lies beneath the runner’s feet reveals a complex construction process where every layer serves a specific purpose.
The Essential Base Layer
The stability of the visible track surface depends entirely on the foundational layer beneath it. This component is typically constructed from either asphalt or concrete, providing a rigid, non-shifting platform for the synthetic materials above. The base layer must be perfectly level and smooth, with a maximum variation of only a few millimeters across the entire surface to ensure the final track is uniform.
The base structure is also responsible for managing water, which is a major factor in a track’s longevity. The base is graded with a slight slope, usually between 0.5% and 1%, to direct water toward perimeter drainage systems. Without this proper slope, water infiltration could damage the synthetic layers, leading to premature failure and inconsistent running conditions.
The Primary Surface Materials
The visible surface of a modern track is a composite material made primarily from two chemical components: polyurethane and rubber granules. Polyurethane (PU) is a synthetic polymer that acts as the binder, holding the entire system together. This resin provides the track with its characteristic elasticity, durability, and resistance to weather and ultraviolet (UV) light exposure.
Rubber granules are mixed into the polyurethane binder, providing shock absorption and energy return. These granules are differentiated by layer and chemical makeup. The lower, thicker cushion layer frequently uses Styrene-Butadiene Rubber (SBR), often sourced from recycled materials like old tires. The top, colored wear layer uses Ethylene Propylene Diene Monomer (EPDM) granules, a virgin synthetic rubber compound known for its superior UV stability and ability to hold color.
How Synthetic Tracks Are Constructed
The method used to apply the polyurethane and rubber materials determines the track’s performance characteristics and cost. These application methods are categorized into three main systems, each offering a different balance of quality and economy.
Full-Pour System
This is the highest quality option, made entirely of polyurethane and rubber granules applied in multiple seamless, non-porous layers. This system is the most expensive but provides the most consistent force reduction and energy return, making it the standard for elite international competition.
Sandwich System
A more common and balanced option, this system combines a porous base layer with a sealed, impermeable top layer. It involves laying a thick mat of SBR rubber granules bound with polyurethane, followed by a final, non-porous layer of polyurethane and EPDM granules. This hybrid structure offers excellent shock absorption and durability at a lower cost than the full-pour method.
Porous or Spray-Applied System
This is the most economical choice, consisting of a porous rubber base mat that allows water to drain through it. A thin, colored layer of polyurethane mixed with EPDM dust is then sprayed onto the surface, creating a textured finish suitable for general use and training facilities.
Historical and Non-Synthetic Surfaces
Before the advent of modern synthetic materials, running tracks were constructed from simple, natural materials that presented challenges for athletes. The earliest tracks were often packed dirt or clay, which became unusable in wet weather and offered little consistency. These surfaces were highly susceptible to erosion and required constant maintenance.
A major step forward was the development of cinder tracks, common through the 1960s, including at the 1964 Tokyo Olympics. Cinder tracks were made from a mixture of coal ash, carbon, and fine rock particles. While they provided a more standardized surface than dirt, they were abrasive, offered poor drainage, and were hard on an athlete’s body. Early attempts at all-weather tracks in the 1950s involved mixing rubber or sand into asphalt, but these surfaces became brittle in the cold or soft in the heat, leading to inconsistent performance. The transition to polyurethane-based synthetics, beginning with the 1968 Mexico City Olympics, marked the end of these traditional surfaces in high-level competition.