Russell E. Carlson, R.C.A., BCMA, Arborist Expert
Case Summary: In the pre-dawn hours, a family of four was driving on a state highway when a tree broke near its base, fell across the road, and landed on their vehicle. Both parents were killed; the minor children in the back seat were injured. The condition of the tree at the time of failure, as well as existing weather conditions, were scrutinized as causative factors. The tree was located at the edge of the state-owned right-of-way. An old box-wire fence was attached to the tree on the side toward the road. The ground at the base of the tree sloped steeply downward toward a naturally wooded swamp. The base of the tree had an open cavity below the major buttress roots on the down slope side, and internal wood decay extended several feet up the trunk.
Expert Analysis: Plaintiffs claimed the species of tree, Ailanthus, or tree-of-heaven, was a contributing factor to the failure because of “rapid growth patterns and weak wood and branch structure.” The presence of the cavity at the base of the tree was claimed as being a “serious and obvious defect.” Plaintiffs also claimed that Ailanthus trees are undesirable for a number of other reasons, most of which had no bearing on the failure of the tree.
Ailanthus trees have softer and less dense wood than some other tree species, but they have denser wood than many other native trees that are considered desirable. This species grows quite rapidly when young, but both vertical and radial growth rates soon slow as the tree ages. The plaintiffs’ assertions that the tree was weak because it grows fast were incorrect. It is considered to be invasive because of its ability to create numerous root suckers, often at the expense of other species, but this was irrelevant to the failure.
A careful review of police photographs, and examination of the incident site, revealed several key facts. The crotches that Plaintiffs said to be weak did not fail. The main trunk leaders above the lowest crotch broke on impact but were not a factor in the whole tree failure that caused the incident. The open cavity at the base of the tree was only visible, prior to the failure, by observing the base of the tree from the side opposite the roadway. The observer would have to climb over the fence and walk through the heavy vegetation and soft ground in the adjacent swamp to see the cavity; any normal and reasonable inspection of trees along roadways does not include such an extensive inspection.
The failure of the tree was the result of hidden internal wood decay, not detectable through standard inspection techniques. The plaintiffs’ case was built on the supposition that Ailanthus trees were undesirable in the landscape, considered invasive, and had characteristics that often led to failures. None of those factors contributed to the tree failure or the fatal incident. Plaintiffs also attempted to place an unsupported burden on the state to make extensive inspections beyond normal and standard procedures.
Result: Case settled.Categories: Environmental | Russell E. Carlson, R.C.A., BCMA