TreeCalc - tree safety online
TreeCalc – tree safety online
Tree safety calculations are based on a comparison of wind force and the resistance that a tree trunk can counter it with. TreeCalc provides the user with numerous calculation parameters, so that the safety status of any individual tree can be estimated as accurately as possible.
TreeCalc uses calculations that are based on the standards set for this field of work (Eurocode 1); it provides tables of all the published material properties of the green wood of different tree species; and it supplies a representative selection of cavity shapes and safety-relevant geometry parameters (e.g. cracks, heart rot in an open stem shell, etc.).
A safety factor is calculated from the various inputs for the tree in question and, if pruning is feasible, a recommended pruning profile is issued along with specific pruning parameters (in m and %). If pruning back the tree is going to reduce the tree’s performance and thus shorten its life, the recommendation will be to remove it. This recommendation should, on all accounts, be critically examined.
In 2015, TreeCalc received the Medal of Innovations at the GaLaBau trade show in Nuremberg.
For more information, go to www.arbosafe.com, www.treecalc.com
ArboStat 2.2 - Analysis software for tree statics
Arbostat 2.2 - Analysis software for tree statics
In the practice of estimating wind effects, a tree’s dynamic interaction with gusts of wind plays an important role. A slender conifer, for example, may experience a dynamic amplification of wind forces due to its high susceptibility to oscillate in the wind; whereas a deciduous tree may balance out wind gusts by the damping effect of its dense crown.
The special ArboStat software makes it possible to conduct wind load analyses that consider dynamic effects and conform to current wind codes. The results of pull tests can be incorporated and evaluated according to engineering standards. ArboStat was the first software to enable the use of the wind models in the German technical standard DIN 1055-4 for evaluating wind load on trees, thereby incorporating the latest research findings regarding the dynamic behavior of tree crowns. A static equivalent load is calculated that complies with German standard DIN 1055-4. This load has the same effect on a tree as a storm with strong wind gusts. It can be directly compared with the results of the pull test.
Diagrams result from these evaluations which classify the tree's stability and/or risk of fracture according to the response evoked by the pull test. The diagrams also graphically illustrate the tree's safety reserves. In connection with the latest developments in measuring instruments for pull tests, it is also possible to statistically analyze the results. If the safety margins are too small, ArboStat can provide an analysis of crown reductions with regard to their impact on the tree's safety.
For more information, go to www.arbosafe.com
Rigging 1.0 - Risk assessment
Rigging 1.0 - Risk assessment
When trees are removed, large and very heavy sections of trunk have to be brought safely to the ground by means of cable systems. The principles of mechanics play a huge role regarding the safety of those working in these often highly critically situations. This also applies to the risk of any kind of damage occurring.
Rigging 1.0 simulates the force of impact of a falling trunk section, on the basis of a physical worst-case scenario. The subsequent calculation is based on the premise that the energy created in the most unfavourable of conditions has to be completely converted into the stretching of the cable. This makes it possible to create simulations at various heights with parameters that the climber can enter, such as the weight of the trunk section, the altitude of the fall, and the cable’s type and length.
The intensity of the force of impact is estimated using a procedure that American biophysicist Dr. Peter Donzelli used a similar one of in his research. The weight values of green wood that were used came from specialist publications and tended to be from the lower levels of a very broad range. Nevertheless, comparisons with load peaks arising during removal work have shown that the force of impact calculated by Rigging 1.0 is significantly higher.
The software was originally created just for training purposes, since the physical calculation model does not record the entire unloading process. However, evidence indicates that the calculations of force of impact in standard situations are always too high. At least there is no risk involved in using it to determine danger potential.
The continuation of Dr. Donzelli’s work has shown that parameters such as the cutting of the felling notch, the shape and actual trajectory of the severed trunk section, and the elastic reaction of the remaining trunk all have a highly significant influence on the load peaks that arise. Dynamic lowering, which makes use of the friction on the lowering device and a smooth deceleration process, considerably reduces the load peaks, of course. However, until it is possible to completely rule out an unintended blocking in the rigging system, this critical case of load should continue to be used in safety analyses.