TS-DC Lambda

Area of Application

The TS-DC Lambda is a debris flow barrier designed for the highest and most difficult loading conditions. Unlike prefabricated systems used for rockfall mitigation, debris flow barriers must always be designed on a site-to-site basis to account for the highly variable characteristics of debris flow processes and their interaction with site topography. These systems are some of the largest and most robust flexible-net structures in the world.

Self Supported

One of the key features is that the posts are self supporting which means that no upslope retaining ropes are required. This is important because any anchors or ropes located upstream of the system will be impact by a wall of debris that could cause the system to fail. A large brace connects the upper portion of the primary post to the back of the foundation and so the support is protected by the structure itself.

Brace-Post Connection

The connection between the primary post and the brace is through tongues with a large diameter pin for ease of installation. The post is subsequently reinforced in this area to resist buckling.

Base Plate

The base plates are designed to be secured to a foundation or bedrock with four bolts. The bolts are normally short pieces tied to the reinforcement elements of the foundation.

Rope Guidances

The bearing and middle ropes are led through a rope guidance integrated at each post head and base plate. Each guidance and post provides large curved surfaces to help protect the ropes and nets and allow unobstructed movement. The guidance is designed to be robust and with no movable parts in order to ensure longevity and zero maintenance.

Lateral Anchorage (Confined)

Loads are spread over the entire height of the structure through bearing rope sets (double ropes), which are spaced according to the loading requirements in increments ranging from 0.5-1.5 meters. For systems terminating at steep walls, ropes with brake elements are not led through the last net panel while its paired rope (without the brake element) is woven through the net. This allows the brake element to expand without pulling the net away from the wall.

Lateral Anchorage (Unconfined)

The system can be anchored at the open ends of the fence or internally using standard anchors or reinforced anchorage. This allows a barrier to be built in long sections, as well as be applied to areas with unconfined flows such as within debris cones. Long barriers consist of multiple sections of fencing that act independently.

Overflow Abrasion Protection

For systems where overflow is anticipated and abrasion is an issue, steel profiles can be added to help protect the upper bearing rope set. The plates cover both the ropes and the upper edge of the net and are installed during the final stages of construction.

AVT-phx Brake Elements

The AVT-phx series of brake elements are steel coils that unravel when a force is applied. The gauge, width and number of coils can be specified in order to control the amount of energy absorbed and the total displacement. With no moving parts, these are some of the safest and most reliable brakes in the industry.


Debris Catchers are designed to address various maintenance requirements based on owners’ needs. For example, zipper seams can be installed to allow disassembly in particular fields. The unique characteristics of the Omega-Net combined with the zipper permits the system to be opened like a drape and gives access to heavy machinery for debris removal. The lack of retaining ropes on the upstream side of the system also greatly reduces the cost of maintenance following an event.

ModelTS-DC Lambda
StyleFixed Rotation
Impact Pressure
up to 150
Available Heights
[m (ft)]
up to 7.5
Primary Net
ModelOmega-Net 7.5/135Omega-Net 9.0/185Omega-Net 10.5/180
TypeSteel Wire CableSteel Wire CableSteel Wire Cable
Rope Diameter
[mm (inch)]
Rope Construction1 x 7 Spiral1 x 7 Spiral1 x 19 Spiral
Single Wire Diameter
[mm (inch)]
Corrosion ProtectionZn/ZnAl (Class A)Zn/ZnAl (Class A)ZnAl (Class A)
Mesh Size
[mm (inch)]
135 x 135
(5.3 x 5.3)
185 x 185
(7.3 x 7.3)
180 x 180
(7.1 x 7.1)
Unit Weight
Mesh Tensile Strength
calculated [kN/m (lbf/ft)]
Connection to Main RopesThreadedThreadedThreaded
Connection to Adjacent Panel3/8" Shackle7/16" Shackle1/2" Shackle

The primary net material used in Trumer systems is called the Omega-Net. It is a steel cable net made from spiral rope that has thick individual wires to resist abrasion. The strands of rope are pre-bent into arcs resembling an omega shape and then woven together to make the net. This process yields an extremely strong net with high flexibility and energy absorption characteristics.

Bearing Ropes
per fence segment
(two upper, two lower)
Max. Rope Diameter
[mm (inch)]
Corrosion ProtectionZn or ZnAl (Class A or B)
Brake Element
per rope
Brake Element TypeAVT-phx
Middle Ropes
per fence segment
site dependent
(sets of two)
Max. Rope Diameter
[mm (inch)]
Corrosion ProtectionZn or ZnAl (Class A or B)
Brake Element
per rope
Brake Element TypeAVT-phx
Support Structure
Post TypeLambda Frame
Post-Brace-Base Connection Hinged
Integrated LadderRungs every 0.5 m (19")
Rope GuidesIntegrated
Base Plate ConnectionTongue and pin
per base plate
4 (x2)
Post Base Support
Base Plate Layout
Lateral Anchorage

Lateral anchorage can be directly to a steep slope (e.g. gully embankments, as shown) or similar to a standard rockfall catchment fence. This allows the system to be used for protection against both confined or unconfined flows.

Typical Cross Section
Typical Layout (Plan View)
Typical Layout (Front View)

NOTE: All data is taken from an example of an existing project. Every debris flow structure is custom designed for a specific site and loading conditions and so the exact details of the system will very from site to site. This is an important aspect of debris flow mitigation and standardized (e.g. CE marked systems) are not necessarily suitable to for this type of mitigation.

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