Pontoon bridge in 638. The army of the Umayyad Caliphate built a pontoon bridge over the Bosporus in 717 during the Siege of Constantinople (717–718). The Carolingian army of Charlemagne constructed a portable pontoon bridge of anchored boats bound together and used it to cross the Danube during campaigns against the Avar Khaganate in the 790s. Charlemagne's army built two fortified pontoon bridges across the Elbe in 789 during a campaign against the Slavic Veleti. The German army of Otto the Great employed three pontoon bridges, made from pre-fabricated materials, to rapidly cross the Recknitz river at the Battle on the Raxa
Flexible cable designs. These are sometimes called “chain-suitable,” “high-flex,” or “continuous flex” cables. A higher level of flexibility means the service life of a cable inside a cable carrier can be greatly extended. A normal cable typically manages 50,000 cycles, but a dynamic cable can complete between one and three million cycles. Flexible cables can be divided into two types: those with conductors stranded in layers inside the cable, and those that have bundled or braided conductors. Stranding in layers is easier to produce, and therefore usually less expensive. The cable cores are stranded firmly and left relatively long in several layers