<P> Special curatores for a term seem to have been appointed on occasion, even after the institution of the permanent magistrates bearing that title . The Emperors who succeeded Augustus exercised a vigilant control over the condition of the public highways . Their names occur frequently in the inscriptions to restorers of roads and bridges . Thus, Vespasian, Titus, Domitian, Trajan, and Septimius Severus were commemorated in this capacity at Emérita . The Itinerary of Antoninus, which was probably a work of much earlier date, republished in an improved and enlarged form, under one of the Antonine emperors, remains as standing evidence of the minute care which was bestowed on the service of the public roads . </P> <P> Ancient Rome boasted impressive technological feats, using many advances that would be lost in the Middle Ages . These accomplishments would not be rivaled until the Modern Age . Many practical Roman innovations were adopted from earlier designs . Some of the common, earlier designs incorporated arches . </P> <P> Roman road builders aimed at a regulation width (see Laws and traditions above), but actual widths have been measured at between 3.6 feet (1.1 metres) and more than 23 feet (7.0 metres). Today, the concrete has worn from the spaces around the stones, giving the impression of a very bumpy road, but the original practice was to produce a surface that was no doubt much closer to being flat . Many roads were built to resist rain, freezing and flooding . They were constructed to need as little repair as possible . </P> <P> Roman construction took a directional straightness . Many long sections are ruler - straight, but it should not be thought that all of them were . Some links in the network were as long as 55 miles (89 km). Gradients of 10%--12% are known in ordinary terrain, 15%--20% in mountainous country . The Roman emphasis on constructing straight roads often resulted in steep slopes relatively impractical for most commercial traffic; over the years the Romans themselves realized this and built longer, but more manageable, alternatives to existing roads . Roman roads generally went straight up and down hills, rather than in a serpentine pattern . </P>

What is the longest road in the roman empire