Journal of Arboriculture 31(2): March 2005 89 THE RELIABILITY OF A WINDSHIELD SURVEY TO LOCATE HAZARDS IN ROADSIDE TREES By C.J. Rooney1 , H.D.P. Ryan2 , D.V. Bloniarz3 Abstract. Hazardous conditions in roadside trees are a constant concern for municipal arborists. Due to fiscal constraints, many municipalities desire an accurate and efficient method to inspect their tree populations. This case study shows that a windshield survey can be used to find hazardous conditions in roadside trees, using a simple system and an experienced Certified Arborist. In addition, the case study showed that the percentage of detected hazardous conditions increased as the conditions became more severe. The percentage of hazardous tree conditions found using a windshield survey in developed sample areas far exceeded those found in undeveloped sample areas. Key Words. Windshield survey; hazard trees; municipal forestry; risk management. , and B.C.P. Kane4 can save time over walking because the arborist is driven along a community’s roads. Windshield surveys are most efficient when the arborist is looking for one or two particular tree characteristics. Windshield surveys have been and continue to be used in many cities and towns throughout the United States. The Urban Forestry Depart- ment in Cincinnati, Ohio, U.S., uses a windshield survey to inventory trees that records the species, size, and condition of the city’s trees (Sandfort 2001). The main purpose of the type of windshield survey used in this case study was to identify hazardous tree conditions throughout the commu- nity and prioritize them based on probability of target impact, size of defective tree part, probability of failure of defective part, and tree species. Many municipalities are struggling financially. With budget shortfalls and increasing costs it is becoming more difficult for municipalities to deliver necessary services. Trees are often on the losing side when poor economic circumstances reduce municipal budgets, because tree planting and maintenance are not considered as important as other services. Unfortunately, many municipalities allocate neither the funding nor the time to take care of their trees properly, and at the same time society is becoming more litigious (Smiley and Fraedrich 1991). Such considerations prompt municipalities toward greater efficiency in community tree management. A consequent benefit of such an increase in efficiency is protecting the community from litigation. A community should exert a reasonable amount of effort toward caring for and inspecting their trees for hazards. The objective of this case study was to compare a windshield survey for hazard trees to a traditional individual hazard tree inventory. Specifically, the case study investi- gated the accuracy and efficiency of both methods and attempted to identify conditions or situations that would favor one method over the other. The hypothesis for the project is that windshield surveys can be reliably used to assess tree defects compared to a traditional walking inspection. To test the hypothesis, a windshield inventory of all town-maintained roads was conducted, then a traditional walking inspection of ran- domly selected samples of the trees was conducted. A windshield survey is a method of evaluating trees whereby an arborist is driven along a community’s roads recording certain tree characteristics. A windshield survey Many sources recommend annual inspections of trees (Grey and Deneke 1978; Kane et al. 2001; Lilly 2001). In a residential setting, tree inspections can include checking tree health and damaged or loose support cables. For a municipality, an annual tree inspection’s main goal is to find tree hazards. Within a year, a tree’s structural and physi- ological condition can change quite easily; weather, humans, insects, and diseases can be major factors that cause changes. Annual inspection of high-use areas such as heavily traveled roads or high-use public parks should help keep an arborist aware of changing situations. The results of an annual inspection can help an arborist plan and schedule upcoming maintenance. An annual inspection can also document that there is a systematic and standardized inspection protocol for assessing the community’s trees. The standardized protocol for hazard assessment is necessary because a number of lawsuits have demonstrated that municipalities are directly responsible for the upkeep and the inspection of their trees. WINDSHIELD SURVEY ISSUES A municipality’s options for inspecting the trees for hazard- ous conditions are (1) do nothing, (2) conduct a thorough walking inspection, (3) conduct a windshield survey, or (4) use a combination of techniques. Given the climate of litigation in the United States and recent court rulings as well as for concerns about public safety, it would be unwise not to inspect the trees, although many communities choose this option. Conducting a thorough, up-close inspection of all the trees in a community is not always feasible for many municipalities due to financial constraints. For instance, ©2005 International Society of Arboriculture
March 2005
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