Roman roads (called Viae Publicae in Latin) were an extremely important construction project for imperial Rome, as they allowed for communication and control of the vast Roman empire throughout Europe. Approximately 50,000 miles (or 80,000 kilometers) of roads were constructed between about 350 BC and 150 AD.
Roman Road Construction
According to the Roman engineer and architect Vitruvius, Roman roads were created by first digging a trench of about 45-60 centimeters in depth. The trench walls were then lined with curb stones inserted vertically into the ground. When necessary for stability, the trench was filled with different layers of gravel, sand and soil. Finally the trench was capped with blocks of flagstones, shaped into polyhedrons with a flat surface and narrow pointy bottoms to fit securely into the matrix. The final road surface had a standard width of 2.4 meters (about 8 feet).
Many many segments of Roman roads are extant today, because of their solid-state engineering, such as the Appian Way, illustrated in the photo, and the Flaminia Consular Road, investigated in a 2007 study of breccias.
Recent studies of Roman roads have concentrated on identifying the provenance of the stone, specifically which quarries were utilized by the Romans for their road construction.
Capedria, Silvio, Riccardo Grandia, and Giampiero Venturelli 2003 Trachytes Used for Paving Roman Roads in the Po Plain: Characterization by Petrographic and Chemical Parameters and Provenance of Flagstones. Journal of Archaeological Science 30(4):491-509.
Vantaggi, Mirco, et al. 2007 Archaeometric and geological constraints for the provenance of carbonatic breccias used in monumental works along the Flaminia Consular Roadnext term (Umbria-Marche, Central Italy). Journal of Cultural Heritage 8(4):434-444.