Visual Tree Assessments and consultation
The VTA-Method (VISUAL TREE ASSESSMENT) consists of three processes. A full visual inspection of the tree is undertaken in order to find any external symptoms of internal defects. If the constant stress distribution in a tree is disturbed due to the presence of a defect the tree attaches more wood at the overloaded spot. Bulges or dents are formed near decayed hollows and ribs near cracks etc.
In Most cases it is usually quite apparent where likely faults and weak points are located within a tree by assessing the combination of various external factors which point towards the overall tree health.
If subtle or oblique symptoms are detected the related defect can be confirmed and measured by deeper inspection. This would be done by measuring the velocity of a sound wave travelling through the cross-section and by drilling methods. The strength of the remaining healthy wood is determined now with an instrument called a fractometer, a wood testing device in pocket-size. In general we provide more basic assessments for trees and in cases where serious methods of analyses are required such as sound wave measurement we would hire in specialist engineers trained in the calibration and use of such methods and instruments.
If defect size and wood quality is known failure criteria are used to decide whether the tree is dangerous or not.
VTA is non-destructive technique for determining the health of trees. Only if there is a reason for increasing concern the tree is subject of deeper inspection but also in this case the wounding of the tree has to be kept to a minimum.