Parallel cable system: Robust and flexible system invented by Freyssinet in 1976. The Freyssinet HD system is based on the principle of complete independence in the operation of each cable. This principle provides many advantages, some of which are:

- Independent installation and pre-tensioning of each cable

- Independent protection against oxidation of each cable

- Independent removal and replacement of a cable if necessary

The HD series has systems from 1 to 169 cables, but there is no limit to the length