**3. Times of the Roman Empire**

The period of the Roman Empire saw an overwhelming abundance of stone, brick and stonebrick arch bridges—apart from military bridge structures, naturally. This period can also be equated with Roman roads. The system and quality of roads enabled movements of the Roman legions and also served civil purposes.

Before we start discussing Roman bridges, however, we need to look at a much older and historically very important road, namely, the Persian Royal Road [10]. It crossed the Persian Empire from Susa or from Persepolis to Smyrna (present-day Izmir). Depending on historical sources, the total length of the road amounted to 2600–3000 km. The road was built by the Persian king of kings, Darius I (c. 550–486 B.C.) and was used as a postal route. It took from 7 to 10 days for the system of courier stations and teams to cover the distance. The road was used by Alexander the Great, and then by the Romans. It was in service for more than 3000 years and coincided with the Silk Road to a considerable degree.

In the town of Diyarbakir (Kurdish: Amed) in south-eastern Anatolia, a bridge called Ten Eye Bridge has been in use till this day, **Figure 3**. It was constructed in the eleventh century, although its dating is connected with the conducted reconstruction. Some historical sources connect this place with the Royal Road and if this were to be the case, it would be one of the oldest bridge crossings in the world. Assuming that 1065 A.D. is a trustworthy date of the reconstruction, the bridge on the river Tiger (Dicle – tr.) comes from the Roman period.

**Figure 3.** The 10-Eye Bridge over the Dicle River in Diyarbakir.

approx. 3000 B.C. to 1000 B.C. Hence, it can be inferred that the bridges are at least 3000 years old and for that reason are considered the oldest existing bridges in the world. Given their age, they are in a superb technical condition. They are not large-scale objects—the width of the light

It should be highlighted that Mycenaean bridges were elements of the road system, which today is known as *Mycenaean Highways* [8] —which may be a slightly exaggerated name. The

Mycenaean bridges are very interesting from the point of view of structural mechanics and construction technology. At the first glance, they seem to be arch structures. But if so, one must admit that these arches are rather accidental. The arrangements of boulders of which the arches are made demonstrate the lack of knowledge with regard to the essence of the arch behaviour. As a matter of fact, they are corbel structures which—as a result of seismic earthquakes—have been degraded to the present shape. Hence, the currently observed cyclopean boulder arches are a result of the transformation of the corbel system into a possible mixed arch-corbel static system. The effort and stability of Mycenaean bridges were analysed in the paper [9]. Identification of the technology of Mycenaean bridges is a great challenge, **Figure 2**. The cantilever slab technology enables construction without scaffolding. If indeed it was so, Mycenaean bridges were a major constructional achievement. Despite the fact that Mycenaean bridges constitute a part of the heritage of mankind, they have not been sufficiently studied. Paradoxically, apart from taking external measures, their ultra-historical character makes it impossible

The period of the Roman Empire saw an overwhelming abundance of stone, brick and stonebrick arch bridges—apart from military bridge structures, naturally. This period can also be equated with Roman roads. The system and quality of roads enabled movements of the Roman

Before we start discussing Roman bridges, however, we need to look at a much older and historically very important road, namely, the Persian Royal Road [10]. It crossed the Persian Empire from Susa or from Persepolis to Smyrna (present-day Izmir). Depending on historical sources, the total length of the road amounted to 2600–3000 km. The road was built by the Persian king of kings, Darius I (c. 550–486 B.C.) and was used as a postal route. It took from 7 to 10 days for the system of courier stations and teams to cover the distance. The road was used by Alexander the Great, and then by the Romans. It was in service for more than 3000 years

In the town of Diyarbakir (Kurdish: Amed) in south-eastern Anatolia, a bridge called Ten Eye Bridge has been in use till this day, **Figure 3**. It was constructed in the eleventh century, although its dating is connected with the conducted reconstruction. Some historical sources connect this place with the Royal Road and if this were to be the case, it would be one of the oldest bridge

term was first introduced by A. Jansen, the author of one of the chapters of this book.

of the flow opening is approx. 1.5 m, its height approx. 2 m, **Figure 2**.

to conduct standard research.

4 Structural Bridge Engineering

**3. Times of the Roman Empire**

legions and also served civil purposes.

and coincided with the Silk Road to a considerable degree.

Here, the dating of the Roman Empire should be highlighted. In most part of Europe, it covers the period until the fall of the Empire in 476 A.D. In the Mediterranean, it is seen as connected with the fall of Constantinople on 29 May 1453. There is a difference of almost one millennium. In these circumstances, Roman bridges in Turkey and Arab countries may be much younger than Roman bridges in Spain.

One of the first bridges on the river Tiber built in 62 B.C. is certainly Roman—according to the both modes of historical dating, **Figure 4**. There is a funny story connected with the bridge: when it was constructed, the payment for work was refused unless it was proved that the structure was durable. The photograph in **Figure 4** was taken in 2008. Nevertheless, the ordering party's anxiety is easier to understand if we take a look at other, even later, Roman bridges, as shown in **Figure 5**.

**Figure 4.** The Pons Fabricius built by Lucius Fabricius, 62 m long, 5.5 m wide.

The bridge is located on a Roman road bearing a Spanish name: *Via de La Plata*. It is over 700 m long. Its elements include processed granite arches. There are 60 arches based on massive pillars. They are heavy, reliable structures.

The Pons Fabricius marked the beginning of a new way of looking at bridges that, aesthetically, are relatively light and this trend has survived in Rome till this day. With the exception of the Ponte Pietro Nenni that carries an underground line, all the bridges in Rome have arches. Among them, one finds the first reinforced concrete bridge in the world, the Risorgimento of 100 m span, constructed in 1912 by F. Hennebique. Also, in 2011, a beautiful pedestrian steel footbridge with shallow arches was built—the Ponte dela Musica.

**Figure 5.** Puente Romano de Mérida, built in first century A.D., Guadiana River.

In the Roman period, bridges known as aqueducts were also built, slender and beautiful in their monumentality. The only load they carried was the dead load with an insignificant addition of flowing water, **Figure 6**.

**Figure 6.** Roman aqueducts, first century A.D.: (a) Los Milagros (the miracles); (b) Segovia aqueduct.

It should be mentioned that during the Roman Empire, but 200 years later, tower aqueducts were constructed. Water flew in a leak-proof pipe located on relatively short arcades. The level differences were solved on the basis of the principle of communicating vessels according to, surprisingly, Pascal's theorem, see **Figure 7**.

**Figure 7.** Views of the Aspendos aqueduct: (a) from the top; (b) from the ground level.
