American Association of State Highway and Transportation Officials

Special Committee on Research and Innovation

FY2023 NCHRP PROBLEM STATEMENT

Problem Number: 2023-B-34

Problem Title

Quantifying deer-vehicle collision rates in response to vegetation management.

Background Information and Need For Research

Nationally, deer vehicle collisions have a significant impact upon roadway safety with fatalities, property damage, and other collateral damage occurring each year. An average of 148 fatalities have been reported nationally each year attributed to deer vehicle collisions (and 6 deaths/year in NYS alone). In relation to property damage, an annual average of 65,000 collisions with white-tailed deer in NYS alone resulted in an average cost of $4,300 per deer-vehicle collision (DVC). With the significant negative outcomes from DVCs, it is important to know and best control for any changes to design and operations which could affect DVC incident rates.

Many DOTs are implementing altered vegetation management practices within their Rights of Way (ROW) to provide pollinator habitat for declining populations, reduce energy demands, improve stormwater quality, maintain grassland bird nesting habitats, reduce spread of invasive species, and to achieve a myriad of other environmental objectives. To accomplish this, mowing practices are being altered to provide early successional stages of flowering vegetation along the ROW by implementation of 1) rotational mowing so that certain areas are mowed at intervals less frequent than once per year; and/or 2) mowing outside of grassland bird nesting and monarch rearing seasons and per Best Management Practices (BMP)s for these habitats. These practices are expected to result in greater vegetation heights and other differing conditions at these locations certain times of the year.

The initiatives to promote early successional habitats within highway ROW have attracted attention from maintenance staff, traveling public, and resource agencies as to the potential effect of increased vegetation heights on potential DVCs. The true effect of altered vegetation practices upon DVCs has not been significantly researched. This study will quantify DVC rates in relation to vegetation management and vegetated conditions along the roadside. The objective of the research is to determine if there are negative, positive, or no impacts of these practices and conditions on DVC rates.

The research is needed to assist DOTs in directing and implementing effective vegetation management practices that best ensure safety objectives to the traveling public and support environmental objectives. The research will assist in effective communication to the public, resource agencies, and DOT staff the effects of altered vegetation management (mowing) on DVC rates.

This problem statement supports the strategic goals of TRB AKR20, Roadside Operations Committee involving roadside maintenance practices and safety and stewardship objectives. The problem statement also supports the objectives of TRB Committee on Environmental Analysis and Ecology (AEP70), and TRB Committee on Landscape and Environmental Design (AKD40).

Literature Search Summary

Data from Pagany et al. (2020) identifies an absence of wildlife-vehicle collision studies in the northeastern U.S. Guyton et al. (2014) posits that deer were observed most frequently in mowed, lowland areas near streams. However, this study took place in Mississippi and did not quantify the number of DVCs associated with vegetation management practices. Stapleton et al. (2019) linked driving conditions and roadway alignments to frequency of DVCs. From the literature mentioned and included below, there is an apparent need to quantify the effects of vegetation management and environmental factors on DVCs.

Pagany, R. 2020. Wildlife-vehicle collisions – influencing factors, data collection, and research methods. Biological Conservation 251.

Stapleton, S.Y., Ingle, A., and T.J. Gates. 2019. Factors contributing to deer-vehicle crashes on rural two-lane roadways in Michigan. Transportation Research Record 2673(10): 214-224.

Guyton, J., J. C. Jones, and E. Entsminger. 2014. Alternative Mowing Regimes' Influence on Native Plants and Deer. Report No. FHWA/MDOT-RD-14-228.

Effect of Reduced Roadside Mowing on Rate of Deer-Vehicle Collisions, Transportation Research Board 92nd Annual Meeting, 2013, 12 p).

Normandeau Associates, Inc. Deer-vehicle crash, ecological, and economic impacts of reduced roadside mowing – final report. May, 2012. Federal Highway Administration, Washington D.C. 2012.

Federal Highway Administration. Wildlife-Vehicle Collision Reduction Study: Report to Congress. Report No. FHWA-HRT-08-034. August, 2008.

Research Objective

The objective of this research is to quantify the frequency of DVCs under two primary vegetation management treatments:

1) Control - where vegetation is maintained by conventional practices with mowing at least once per year and no timing constraints; and

2) Experimental – where vegetation is managed as an “adopted area” with conservation measures including:

o Conservation Mowing only outside of monarch development and bird nesting seasons and per Best Management Practices (BMP)s for these habitats

o Rotational mowing at intervals less frequent than once per year

Other factors that may influence the DVC rates will also be considered and could include but are not limited to: plant species composition within the ROW; distance of forested area to DVC; roadway infrastructure/design; landcover; and/or any other features identified to affect the relationship of the vegetation management practices and the rate of DVCs. Data will be collected year-round to evaluate the effects of seasonality as an additional co-variate for vegetation management.

Upon completion of the project, peer-reviewed journal articles, a final report, and guidance for vegetation management as it relates to DVCs will be provided.

Major tasks for completion of the research project include:

• Engaging a research team and developing a detailed scope, schedule, and budget

• Identifying sampling locations that should include multiple states with varying climate/vegetation conditions. Research locations would include “Control” areas with traditional vegetation management practices (conventional mowing) and “Experimental” areas with altered practices during the period of study.

Urgency and Potential Benefits

Deer-vehicle collisions pose significant safety risks to drivers with an average 148 deaths nationally and 6 deaths/year in NYS. Many DOTs are implementing altered vegetation management practices within their ROWs to provide a myriad of environmental objectives. The effect, if any, of increased vegetation heights along the roadside (e.g. pollinator habitat) on DVCs is a critical and urgent concern for state DOTs and other highway agencies to best understand, implement, and communicate their programs to the public, resource agencies, and DOT staff.

Currently, there are few studies quantifying the effects of vegetation management - consistent with early successional habitats - on the frequency of DVCs. Conducting this research will enable DOTs to make informed decisions regarding the implementation of environmentally supportive vegetation management practices, define any safety aspects related to these practices and DVCs (positive or negative), refine practices (if needed), and have information that supports their decisions.

Implementation Considerations

This research will inform DOTs about the potential risks (or benefits) associated with early successional vegetation management practices as it relates to DVCs within our ROWs and provide for best practices for determining the placement of conservational measures at locations along the roadside. This research supports the strategic goals and objectives of TRB standing committees AKR20, AEP70, and AKD40. These technical committees may aid implementation efforts as the study unfolds. Maintenance and environmental staff will primarily be responsible for implementation following the results of this research. State DOTs will implement the information from the results of this research through the development of guidance and policy. Existing collector applications for roadkill (for example, https://roadkillapp.com/) may be used to aid DOTs recording deer collisions within study areas. State police accident reports may also be used to supplement data collected by DOT staff.

Recommended Research Funding and Research Period

Research Funding: $2,000,000 to accomplish the research objective. This estimate includes development of the research process for collection of DVC data by the state DOTs for the research locations, identification, and evaluation of the conditions within the control and experimental areas, evaluation of results, development of conclusions and report, and development of guidance identifying the results and any recommendations for refinements to practices based on the results.

Research Period: 48 months to complete the research, plus an additional 1 year to conduct communications activities in support of results and subsequent publication(s) and guidance.

Problem Statement Author(S): For each author, provide their name, affiliation, email address and phone.

Christopher Standley, NYS Dept. of Transportation, christopher.standley@dot.ny.gov, 518-485-0367

Laura Greninger, NYSDOT, laura.greninger@dot.ny.gov, 518-457-4469

Potential Panel Members: For each panel member, provide their name, affiliation, email address and phone.

Christopher Standley, NYS Dept. of Transportation, christopher.standley@dot.ny.gov, 518-485-0367

State DOT representatives (potential members/friends of AKR20 and AEP70)

FHWA Representative

Pollinator Specialist with Monarch Venture or Xerces

Others TBD

Person Submitting the Problem Statement: Name, affiliation, email address and phone.

Christopher Standley, NYSDOT, christopher.standley@dot.ny.gov, 518-485-0367