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Road Engineering Journal
Copyright © 1997 by TranSafety, Inc.
September 2, 1997
TranSafety, Inc.
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Rotary Intersection a Winner
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Survey Finds State DOTs Feel Biodiversity is a New Issue in Transportation Development Projects

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Survey Finds State DOTs Feel Biodiversity Is a New Issue in Transportation Development Projects

In 1995, the Transportation Research Board's Task Force on Natural Resources (A1F52) conducted a national survey of state transportation agencies. The survey's intent was to determine if and how the agencies addressed biodiversity in their projects. In their article "Current State of Biodiversity Impact Analysis in State Transportation Agencies" (Transportation Research Record 1559), Robert L. Herbstritt and Anne D. Marble discussed the results of the survey. Because transportation projects can significantly affect biodiversity, it is likely transportation agencies will become increasingly involved in analyzing that impact. To date, however, transportation agencies receiving federal funds are not required to analyze their projects' impact on biodiversity.


In their report, the authors gave a definition of biodiversity from a recent book by Edward O. Wilson, a biologist in the field of biodiversity. Wilson's book defined biodiversity as:

The variety of organisms considered at all levels, from genetic variants belonging to the same species through arrays of genera, families, and still higher taxonomic levels; includes the variety of ecosystems, which comprise both the communities of organisms within particular habitats and the physical conditions under which they live.

Editor's note: It might be helpful to share two less complex definitions of biodiversity that we found in on-line reference sources. The Merriam Webster "Britannica Online" defines biodiversity as "biological diversity in an environment as indicated by numbers of different species of plants and animals." The on-line "BioTech Life Sciences Dictionary" from BioTech Resources describes biodiversity as "[t]he existence of a wide range of different types of organisms in a given place at a given time."


The survey asked each state department of transportation (DOT) the following questions:

  • Has the biodiversity issue been raised in the highway development process?
  • If so, how has the subject arisen?
  • Which agencies have requested information?
  • What type of information has been requested and for which projects?
  • What was the DOT response?
  • Is it your understanding that biodiversity is becoming a new issue?
  • Have you completed any biodiversity studies?
  • Were significant impacts identified? Was the information used to make project decisions?


Thirty-two state DOTs responded to the survey. Twenty-one (66 percent) replied that the issue of biodiversity had been raised during the highway development process. Eleven of the 32 (34 percent) said that to date biodiversity had not been an issue in their transportation development process. Of the 21 state DOTs that said the issue of biodiversity had been raised, only Louisiana, Pennsylvania, Virginia, and West Virginia indicated they had completed or were completing studies specifically dealing with biodiversity. Arkansas, Illinois, and Minnesota "reported being involved in corridor acquisition or enhancement programs dealing mainly with the enhancement and maintenance of prairie grass corridors in the Midwest." Thirteen states said that while they had not been involved in any large-scale studies, "they have been asked to consider impacts on biodiversity in a qualitative manner in relation to connectivity of habitats, effects of habitat fragmentation, secondary impacts, and cumulative impacts."

Many states indicated the U.S. Fish and Wildlife Service (FWS) was the government agency that most often asked for information concerning biodiversity. Among other agencies requesting information were the Environmental Protection Agency (EPA) and the U.S. Army Corps of Engineers (ACOE).

The biodiversity issues revealed by the survey were in three categories, though it should be noted "these categories are significantly interrelated, particularly Categories 2 and 3."

Category 1: Protecting Unique, Rare, or Sensitive Habitats/Species

While such action is not a pure method of biodiversity protection, it is nonetheless a "significant component." This type of protection frequently involves a regulation with which DOTs must comply; consequently, "all of the DOTs practice this type of biodiversity protection. However, if this is the only strategy employed, it often results in a piecemeal approach that responds only to crisis situations when species or unique habitats have become extremely rare and endangered." Maine, California, Virginia, and Florida were among the states that had addressed this biodiversity issue.

Category 2: Minimizing Fragmentation and Promoting Connectivity of Habitats

Strategies designed to address this issue included forest patch analysis and connectivity studies. Several DOTs had employed Category 2 strategies, including Pennsylvania, West Virginia, Kansas, Texas, and Louisiana.

Category 3: Managing Watersheds and Ecosystems

Arizona, Colorado, and Montana replied "that they are beginning to take a larger ecosystem approach to the issue of biodiversity." Like Arizona, the DOTs in Idaho, Pennsylvania, and Utah "have developed state-specific programs of biodiversity using the gap analysis method." This method "is beneficial because it identifies gaps in the representation of biodiversity and can be used to evaluate large regional areas." However, these states have not incorporated gap analysis in projects related to transportation.


There was no apparent consensus among the DOTs on the exact meaning of the term biodiversity, nor on the most effective methods to measure or evaluate impacts on biodiversity. Also, most of the states had not conducted studies designed to measure those impacts. However, the majority agreed "biodiversity is becoming a new issue in the transportation development process."

Copyright © 1997 by TranSafety, Inc.

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