The roads general authority (rga) has detailed the engineering specifications governing the structural layers of the road network across saudi arabia. the four-layer structure of soil:ayer structure of soil, gravel, and asphalt is designed to improve network quality and support the strategic objectives of Saudi Vision 2030.

According to Saudi Press Agency, the authority explained that the road structure begins with a sub-base layer measuring up to 30 centimeters thick. Composed of organic-free gravel and sand, the layer is designed to withstand heavy traffic pressure and maintain structural stability. Above it is a gravel base layer, also measuring up to 30 centimeters thick. Made of high-grade gravel, it absorbs traffic stress and distributes weight evenly across the underlying sub-base.

The pavement is completed with two asphalt layers. The asphalt base layer, with a maximum thickness of 20 centimeters, reduces structural pressure, enhances drainage, and protects the foundation from moisture. An asphalt surface layer of up to 5 centimeters caps the structure, providing a smooth and durable driving surface while withstanding traffic friction and severe weather conditions.

The RGA noted that these measurements represent maximum engineering thresholds and may vary according to traffic volumes, site geography, and environmental factors. It reiterated its commitment to modern engineering standards and regulatory compliance through measures including the Saudi Road Code. These efforts aim to ensure high levels of safety, efficiency, and sustainability across the national road network.