| When a rock falls from a
great height, it slides, rolls, bounces, and is airborne, and,
upon impacting the rock slope, breaks into pieces (Video
- Barrier Testing (56M) ). When the rock reaches
the pavement or the rockfall mitigation fence (RMF), it gains
great kinetic energy and flies and spins at high velocities.
This gravely threatens the safety of the traveling public on
the highway below, as demonstrated in many rockfall incidences
like the one on I-70 at Georgetown Hill in May, 2004. RMF is
composed of three major components: steel fence net, steel fence
post and steel cable with its lower end anchored on rock slope.
When a high-velocity spinning rock touches RMF, it can shear
off the cable and/or net, knock down fence post and, thus, destroys
the fence system (Images - Unprotected
cable damage).
Among many mechanisms of protecting the fence system, the
CNC cable protection sleeve with the trade name, CNC/ILDS
sleeve, which loosely fits on the cable (Protected
cable using CNC/ILDS Sleeves), simply spins and
deflects the rock upon impact, thus avoid the damage to cable.
The Colorado Department of Transportation performed rock rolling
experiments after the installation of new RMF at Georgetown
Hill fitted with the CNC/ILDS sleeves and found the sleeves
to be effective in protecting the cable, and, thus, the RMF
system.
The CNC Cable protection system includes large sleeves to
fit around the double-folded cable near its anchor, small
sleeves around the cable, a removable collar between the large
and small sleeves and a washer between all neighboring sleeves.
It is noted that any portion of the cable exposed without
the protection of CNC/ILDS sleeves will surely increase the
chance of cable shearing and the fence destruction. Please
contact us for
more information. |
