Roadside tree risk management by state departments of transportation in the Mid-Atlantic region

We conducted a pilot study in collaboration with Virginia Department of Transportation (VDOT) to ascertain current conditions and capabilities for roadside tree risk management by state departments of transportation (DOTs) in the Mid-Atlantic region. Our focus was specifically on risks associated with tree failure that result in debris falling into the roadway and possibly causing harm to pedestrians, cyclists, vehicles, or roadway infrastructure. The purpose of this study was to benchmark VDOT’s operations relative to its peer agencies and to shed light on the prevailing standard of care for tree risk management amongst state DOTs. With this information, VDOT aims to evaluate its operations and identify opportunities to strengthen its existing capabilities. We surveyed the statewide roadside vegetation management coordinator in Virginia and in the bordering states of Kentucky, Maryland, North Carolina, Tennessee, and West Virginia. We distributed a survey comprising 38 multiple-choice and short-answer questions to the respondents via email in April 2017. We developed the survey instrument in close consultation with VDOT and reference to industry standards, industry best management practices, and primary literature on tree risk management. In the survey, we examined four primary determinants of tree risk management conditions and capabilities: personnel, policies, procedures, and practices. Survey response data were examined to uncover basic themes, trends, and perceptions that might help clarify the prevailing standard of care for tree risk management amongst these state DOTs. VDOT is the only state DOT that currently has an ISA Certified Arborist leading its statewide operations and the only state DOT where most DOT tree management personnel are both an ISA Certified Arborist and an ISA Qualified Tree Risk Assessor. Training on tree risk management for VDOT personnel is above average in terms of frequency, but it is difficult to ascertain from this survey whether VDOT’s workforce is comparable to other states in terms of sheer numbers. VDOT was consistent with the majority of respondents in stating that resources and expertise for effectively managing roadside tree risk are inadequate, yet believing that the DOT is effective at managing roadside tree risk. The policy situation with these DOTs was difficult to ascertain with a survey, and our study constraints did not allow us to delve independently into various state policy documents. The key finding is that the majority of state DOTs currently do not possess a tree risk management policy and have no intention to develop one. Although VDOT does not currently have a policy, it did indicate intent to develop one in the future. Most states (including VDOT) reported that they currently do not have a standardized process for either inspecting roadside trees or rating tree risk. State DOTs were very similar in their use of both drive-by and walk-by tree inspections. That most states only occasionally utilize drive-by inspections should be a matter for further inquiry and clarification as it might indicate that trees are not receiving adequate inspection. The expertise of DOT tree management personnel appears to be underutilized for selecting trees to be planted at the roadside and protecting trees from excessive impacts during roadway construction and maintenance. Not much could be gleaned from the survey about DOT tree removal practices other than removal decisions are not ceded to DOT contractors and are influenced by the opinions and demands of the public. Almost all DOTs (including VDOT) reported that their pruning practices are primarily reactive, addressing branch and crown defects after they have reached a potentially hazardous state. Further, most DOTs indicated that proactive pruning to prevent branch and crown defects is very underutilized (VDOT was slightly better, but still underutilized). In the following report is a full description of the study rationale and methods along with a comprehensive reporting of the survey instrument and survey data. We provide interpretation and insights for the survey results along with a discussion of study limitations and aspects of the study needing further investigation. Where appropriate, we have described what we perceive to be inadequacies in tree risk management operations relative to industry standards, best management practices, and primary literature on tree risk management.