Hazard Tree Programs

Hazard tree inspection programs

An organization with multiple sites to consider should develop a policy and a program for its implementation. Following are some considerations.

Appropriate frequency and intensity of inspection

Based on consideration of such things as types of targets, frequency of use, season of use, status of the tree community (species, age, defects, etc.) and failure history, an inspection cycle and procedure should be determined for various categories of sites. For example, one extreme is rural roads closed in the winter in areas where failures tend to occur in winter. It is probably reasonable to have no formal inspection of such roads. Some year-round roads in areas of high failure potential might receive a “windshield” or roadside walk-by inspection, supplemented by closer examination as circumstances warrant. The other extreme might be a site subject to severe winds with overmature trees and buildings occupied day and night, year round. Two inspections per year might be appropriate in such a situation.

Inspections need not all be of the same intensity. For instance, it may be determined in some circumstances that every three years there will be a thorough, tree-by-tree, pull out all the plugs, no-holds-barred inspection, and in the intervening years there will be a more cursory walk-through inspection without recording individual tree data. The latter type of inspection is geared toward finding things that changed quickly: storm damage, partially uprooted trees, widow-makers. Also, records of the most recent thorough inspection can be used to more carefully observe trees that were noted as needing watching.

Inspectors should be trained

Inspectors should be familiar with trees and tree defects and should receive documented training on tree defects, hazard rating and inspection procedures. This is often available from U.S. Forest Service forest health protection offices, state cooperative extension or other state agencies, some universities, or private sources, which may be found via the International Society of Arboriculture.

Effort should be continuous

Reacting to outbreaks of tree failures is sometimes necessary, especially when inspections have been neglected. But a proper program is continuous. Annual work is planned such that sites are revisited at an interval that is deemed to be adequate as discussed above. If budget is limiting, this should be formally acknowledged, the inspection and treatment cycle adjusted accordingly, annual work rescheduled on that basis, and in extreme situations sites should be closed until they can be properly inspected and treated.


All decisions, training, inspections and treatments should be documented. Documentation of inspections should include results. In event of an accident that results in litigation, this helps to demonstrate organized, detailed efforts to reduce hazard and can provide evidence that particular trees were inspected. It also can help track the progress of the program, detect trends in disease and hazard development in the recreation sites. These records are more likely to help than hurt the organization in court. If there is no record of inspection, a litigant may assert that it was not done.