Certified Arborist Test Cabling Bracing and Support Systems 2

Question 1

What is the difference between a static cabling system and a dynamic cabling system in tree support?

Accepted Answer

Static systems use rigid steel cables that prevent movement at the defined limit; dynamic systems use flexible, elastic synthetic materials that allow some movement and energy absorption before reaching maximum resistance

Answer

Static systems use steel cables; dynamic systems use synthetic rope — the material is the only meaningful difference

Answer

Static systems are installed by utilities; dynamic systems are installed by private arborists — they differ only in who installs them

Answer

Static systems are used for small branches; dynamic systems are designed for large multi-stem trees only

Question 2

What hardware is used to anchor cabling systems within tree stems, and what are the minimum specifications for its installation?

Accepted Answer

Threaded rod (thru-bolts) for cabling anchors, typically minimum 1/2 inch diameter through-bolts for cables, installed through the full stem diameter with plates and nuts on both sides, or lag screws of appropriate diameter and penetration depth

Answer

Galvanized wood screws are used for small cables; lag bolts are used for larger cable systems — no minimum diameter specifications exist

Answer

U-bolts are attached to the bark surface without penetrating the wood — this avoids creating wounds in the tree

Answer

Cabling anchors are always attached to the branch bark ridge at union points where the wood is densest and strongest

Question 3

When is bracing (rod installation) used rather than or in addition to cabling, and what structural problem does it address?

Accepted Answer

Bracing addresses split or cracked unions and co-dominant stems with existing or incipient cracks, providing rigid resistance to spreading forces within a structural defect zone that cables above cannot adequately control

Answer

Bracing rods are installed through the main trunk to prevent root plate failure — they replace cabling for trees with root problems

Answer

Bracing is used exclusively on large conifers to prevent snow-load failure — it is not appropriate for broadleaf trees

Answer

Bracing rods are a temporary support measure installed while a tree heals — they must be removed once callus covers the installation site

Question 4

What is the recommended cable installation height for a two-point high cabling system, and how is it determined?

Accepted Answer

Cables are typically installed at two-thirds the distance from the defective union to the end of the structural part being cabled, to maximize the mechanical advantage while leaving adequate anchoring length above

Answer

Cables should always be installed exactly at the midpoint between the union and the tips of the structural parts

Answer

Cable height is determined entirely by the location of suitable hardware anchor points and available stem diameter

Answer

Cables must be installed at the highest possible point in the tree for maximum effectiveness — they should be as close to the branch tips as possible

Question 5

How often should cabling and bracing systems be inspected, and what does inspection involve?

Accepted Answer

ANSI A300 Part 3 recommends annual inspection of all cabling and bracing systems by a qualified arborist, assessing hardware condition, cable tension and integrity, wood condition around anchors, and changes in the underlying structural defect

Answer

Cabling systems are permanent and need no inspection — the hardware is designed to last the life of the tree

Answer

Cabling systems need inspection only after major storm events — routine annual inspections are not required by any standard

Answer

Inspection is required only when a cabling system is more than 10 years old — newer systems are assumed to be in good condition

Question 6

What factors determine whether a tree with a structural defect should be cabled or removed?

Accepted Answer

The decision depends on risk assessment results, the tree's intrinsic value (historical, ecological, aesthetic), the likelihood that the cabling system will successfully mitigate the risk, the owner's risk tolerance, and whether the risk can be reduced to an acceptable level through supplemental support

Answer

Trees with any structural defect should be removed to eliminate liability — cabling is never an adequate alternative to removal

Answer

If a tree has been standing for more than 20 years with a defect visible, it should be cabled — age indicates the defect is stable

Answer

The decision is purely financial — remove if replacement cost is less than the cabling system installation and inspection costs over 10 years