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Publication Number:  FHWA-HRT-17-008     Date:  December 2017
Publication Number: FHWA-HRT-17-008
Date: December 2017


Evaluation of Promoting Roadside Revegetation: An Integrated Approach to Establishing Native Plants

3. Evaluation Findings

3.1 End Users’ Adoption of Roadside Revegetation Practices

The first high-level question the project team addressed concerned whether Roadside Revegetation had encouraged and helped stakeholders change or supplement their native roadside revegetation practices.(1)

The project team found that end users have adopted the Roadside Revegetation practices by using the guide as a reference tool to reinforce practices that agency policies already mandated.(1)

Literature Review Results

In 2011, FHWA documented the results of a domestic scan aimed at developing a better understanding of processes and techniques used in successful and innovative projects using native plants for roadside revegetation.(14) The scan was also intended to compare the FHWA revegetation effort with projects completed by other agencies to see whether the FHWA revegetation resources had influenced what others were doing. A key finding was that there were many interconnected elements involved in both the technical and non-technical aspects of the revegetation process, all of which should be addressed in a project revegetation plan. Notably, the non-technical aspects—planning, design, implementation, monitoring, and maintenance—were found to be just as critical to the success of revegetation projects as the technical aspects.

Apart from the scan report, the literature review revealed that many FLMAs already have policies, procedures, and guidelines in place for the use of native plants when revegetating roadsides after disturbances. For example, NPS has a conservation policy originating from the late 1980s and early 1990s that calls for the preservation of native plant communities and their genetic resources wherever possible in natural zones.(15) The NPS requires that revegetation of park lands use germplasm taken from populations as closely related genetically and ecologically as possible to park populations. Accordingly, road slopes and other large areas intended to support self-sustaining native plant communities will usually be restored with local genetic stocks of native species. To support the implementation of this policy, NPS has created a Transportation Revegetation Program whereby a team at the NPS Denver Service Center can recommend revegetation strategies (salvage, propagate, or purchase), choose appropriate native species, and assist park personnel in seed and/or cuttings collection.(15) Because many park units in the NPS system do not have the personnel, expertise, or equipment required to propagate quantities of the required native seeds and plants, and few regional offices have plant ecologists or landscape architects available, in 1989, NPS and the Natural Resources Conservation Service developed and signed a cooperative agreement to share technical expertise and develop indigenous native plant materials for use in park revegetation programs.(15) Additionally, some park units, such as Denali National Park & Preserve, do have their own revegetation manuals.(16)

USFS has a similar native plant materials policy that predates Roadside Revegetation.(17,1) According to the policy, native plant materials are to be given primary consideration when selecting plant materials for use in land management projects. Land management prescriptions must include the selection and use of native plant species that are genetically appropriate and adapted to on-the-ground ecological conditions. The policy also requires these prescriptions be written and/or approved by a plant materials specialist who is knowledgeable and trained in the plant community type where vegetation management will occur.

Documents collected also showed that BLM has guidance for the use of native plants for habitat restoration along with other uses such as roadside management. 3 BLM, which maintains a large transportation network made up of approximately 76,088 road mi, 776 bridges, and 18,412 mi of multiple-use trails, has a number of programs related to native plant restoration. In 2001, Congress formed the Native Plant Materials Development Program, which BLM administers, to help ensure a stable and economical supply of genetically appropriate native plant materials for use in restoration and rehabilitation efforts on public lands.(18) BLM’s Seeds of Success program works to support this program and collects wildland native seed for research, development, germplasm conservation, and ecosystem restoration. 4( 18)

For State transportation departments, the project team collected 16 manuals that incorporate specifications for the use of native plants along roadsides. At least nine State transportation department websites were documented that provide information promoting the use of native plants along roadsides. Other collected literature included research and case study documentation conducted within the United States and Australia. Collected documents cover a range of topics related to the installation and maintenance of native plants along roadsides. See appendix C for an annotated bibliography of literature related to Roadside Revegetation.(1)

Of particular interest is the body of literature that has specifically cited Roadside Revegetation.(1) The prevalence of citations of the technical guide across several years suggests that the guide has become integrated into the state of the practice. 5

Primary and Secondary Hypotheses and Key Measures of Effectiveness (MOEs)

The project team reviewed visitation statistics to the Roadside Revegetation website, which Google® Analytics™ provided.(4,28) The team hoped to further understand the extent to which users have expressed interest and awareness in Roadside Revegetation.(1) The overall trend shows an increase in website visitation over time (see figure 1).

Screenshot. Roadside Revegetation website sessions (January 1, 2010, through February 17, 2015).  This screenshot is of the Audience Overview visitation statistics to the Roadside Revegetation website provided by Google® Analytics™.  The visits were tracked from January 1, 2010, through February 17, 2015, and show an increase in visitation over time to the website.

Source: FHWA.

Figure 1. Screenshot. Roadside Revegetation website sessions (January 1, 2010, through February 17, 2015).

The website logged 44,621 total users from January 1, 2010, to February 17, 2015—approximately 24 per day.(4) Over 7,000 of those users returned to the website more than once. The data show that the most visited pages included those pointing to chapters in the technical guide itself. Specifically, “Chapter 3: Road Plans and Terminology,”“Chapter 5: Assess Site,”and “Chapter 10.3: Implementation Guides, Installing Plant Materials”received the most visitation (see table 3).

Table 3. Website statistics from January 1, 2010, through February 17, 2015.


New Users

Returning Users

Total Users







Page views


Pages per session


Average session duration

1 min 14 s

Average time on page—learning page

2 min 24 s


Average time on page—training page

31 s


Average time on page—home page

1 min 13 s


Most popular landing/exit pages—chapter 3


Most popular landing/exit pages—chapter 5


Most popular landing/exit pages—chapter 10


---No data available.

Feedback from the Field

Roadside Revegetation has experienced widespread distribution.(1) Between 2009 and 2013, WFL received requests for the guide—either via hard copy or electronic download—from all continents except Antarctica. Countries requesting the guide included Australia, Brazil, Canada, China, Egypt, France, Germany, Italy, Peru, Spain, Slovenia, and Sweden. An equally global audience was reached via the following conferences and workshops at which Roadside Revegetation was presented:

Roadside Revegetation was also used as a training course guide and as a resource for university courses.(1) Specifically, the guide was a centerpiece at the Western Forestry and Conservation Association’s January 2010 training, “Restorationof Disturbed Sites with Native Plants: An Integrated Approach,”in Vancouver, WA. The audience at the workshop included BLM, FHWA, USFS, and NPS staff, as well as personnel from non-governmental organizations and consulting firms.

Similarly, Roadside Revegetation has been used as course material at the University of Washington and University of Montana. In Montana, hard copies of Roadside Revegetation were also used as a textbook in a College of Forestry class.(1)

In light of the extensive interest in the materials, FHWA and USFS staff have received overwhelmingly positive feedback via face-to-face interactions, telephone calls, and emails, with much of this feedback coming from State transportation departments. Anecdotal praise from both domestic and international end users complements the notion that the guide is well received and that interest (as shown via Web statistics) is sustained.(1) Some recent examples of this feedback include an email from a professor of ecology at the National University of Mongolia in May 2015 who noted that the website represented excellent work and thanked FHWA staff for their efforts 6 A researcher from the Korea National Arboretum added, “The Roadside Revegetation book is [a] very useful textbook for us to develop our research project. We are interested in revegetation using native plants in Korea. Recently, we used fast growing trees and shrubs imported from foreign country. These kind of plants are invasive in Korea’s natural habitat Iwould like to keep in touch with you [regarding the topic].7

Comparable feedback has been received from domestic end users. An individual with the Oregon Department of Transportation said in June 2015, “Your Roadside Revegetation work with Western Federal Lands is THE seminal document on the subject and I have carried it with me for the last 5 years. Congratulations on such an important publication.8 A Washington State Department of Transportation reader said, “As the Landscape Architecture office of the NW region in Washington State, we are constantly on the lookout for publications that will provide good, solid documentation for restoring roadsides. Our office consists of Landscape Architects, Landscape Designers, and CADD operators all with a strong desire to ensure that the roadsides that we design and build are sustainable. Would you please send us copies of Roadside Revegetation [?].9

The interviewees in this evaluation also shared their praise for the technical guide and website, with one NPS staff member stating that Roadside Revegetation “pulls together a lot of useful information into one location.10 (1,4) This person recommends the technical guide to other park units.

In addition to anecdotal praise, the revegetation material was selected as an AASHTO focus technology. AASHTO’s Innovation Initiative (formerly its Technology Implementation Group (TIG)) actively seeks out proven advancements in transportation technology and selects highly valuable innovations with a significant benefit to other agencies. The AASHTO TIG executive committee determined that Roadside Revegetation warranted creation of an information piece that was placed on the AASHTO Innovation Initiative website to help increase awareness of the materials.(1, 29) Likewise, FHWA’s Public Roads December 2007 issue includes an article that discusses the greening of public roadsides and describes the valuable information presented in Roadside Revegetation.(30)

Survey Results

The survey elicited 71 total responses. Of the 54 responses that included more than a person’s contact information, 21 states and the District of Columbia were represented. Responding agencies included FHWA, USFS, NPS, USFWS, and two State transportation departments. (See references 39, 8, 6, and 3.) Of the 38 FHWA responses, 19 were from FLH, 18 were from State division offices, and 1 was from FHWA headquarters. The 19 FLH responses included 7 each from WFL and Eastern Federal Lands and 5 from Central Federal Lands.

Respondents became aware of Roadside Revegetation and its related materials primarily via training courses that FHWA and USFS conducted at various locations in the Pacific Northwest and from FHWA headquarters or a division office.(1) Others indicated that they learned about the technical guide during an annual botany meeting that the USFS hosts, from NPS’s Denver Service Center, from USFS headquarters and field offices, and through Internet searches on roadside revegetation practices.

The ways that agencies have used the guide have varied. Multiple individuals noted that they primarily used Roadside Revegetation as a general reference guide, particularly while on project sites, in writing revegetation plans, while designing monitoring protocols, in developing scopes of work, and in analyzing data.(1) One interviewee commented that the guide is particularly helpful on maintenance topics, especially for those staff members who only have a general awareness of vegetation management. Other respondents noted that their agencies had incorporated Roadside Revegetation’s methods into existing restoration practices and construction and materials specifications, especially in coordination with USFS’s Restoration Services Team, adding that the information in the guide is “invaluableto the profession.11 An interviewee supplemented this thought, stating that the “authors have worked closely with engineers to be on the same page regarding site preparation. The guide is a good reference for helping to address the complexities that different sites present.12

There was also evidence that Roadside Revegetation has encouraged some agencies to change and improve specific roadside vegetation management practices.(1) Responses highlighted how the technical guide has allowed practitioners to better define future conditions and end goals for project sites. With the guide, overall project planning now has an emphasis on coordination with engineers regarding specific planting design specifications. Similarly, prior to the publication of Roadside Revegetation, anecdotal evidence was often used for outcome measures. The technical guide provided a way to develop benchmarks against which outcomes might be better measured. One interviewee commented, “Previously,we did a great job of what we had to do, but the end result wasn’ t always what we wanted it to be. We needed to define the end result better. We were getting low germination; soil was compacted; we wanted more. We never said, if we don’ t achieve X we’ ve not succeeded. The guide offers useful information on monitoring.13

Additionally, Roadside Revegetation has improved practices related to soil and site-specific seed mixes, most notably in promoting the use of native plants instead of ornamental species.(1) According to one respondent, the guide has also increased the use of erosion control devices in lieu of simply using sediment control devices.

A minority of survey respondents noted that Roadside Revegetation had not led to any particular change in revegetation practice.(1) Some respondents pointed out the fact that their agencies had put native revegetation polices in place prior to development of the technical guide. Another respondent noted that its agency’s revegetation projects are usually small in scale and therefore did not believe the technical guide to be applicable.

A total of 27 survey respondents indicated that they were not aware of Roadside Revegetation.(1) While these respondents were generally spread across the country, there was a concentration of seven respondents from the southeast who did not know about the guide, suggesting there may be an opportunity for renewed outreach in that region.

3.2 Establishment of Native Plants and Other Positive Outcomes

The second high-level question the project team addressed is whether the Roadside Revegetation guide and related materials improved the establishment of native plants and resulted in other positive outcomes.(1) This question examined the relationship between activities, outputs, and short-term outcomes with medium- and long-term outcomes in the logic model. In other words, have the development and promotion of Roadside Revegetation and related materials, awareness of the materials, and adoption of the promoted techniques resulted in positive outcomes for the environment, safety, visitor experience, and maintenance costs?

Roadside Revegetation has generally improved erosion, sustainability, environmental stewardship, and visitor experience outcomes.(1) There is less indication that the technical guide has helped to improve safety or reduce maintenance costs.

Survey results suggested that the majority of survey respondents agreed or strongly agreed that Roadside Revegetation has helped improve erosion outcomes, facilitate a more sustainable designed roadway, improve visitor experience, and enhance environmental stewardship.(1) The findings also suggested that a majority of respondents had neutral views on whether the technical guide has helped improve safety or reduce maintenance costs (see figure 2).

Graph. Degree to which survey respondents agreed with statements about Roadside Revegetation. This graph presents the findings of a survey on the degree to which respondents agreed that the Roadside Revegetation website helped to enhance environmental stewardship, improve visitor experience, reduce maintenance costs, design revegetation more sustainably, avoid or reduce erosion, and improve safety.  The Y-axis is labeled “Number of Respondents” and starts at 0 and goes to 40 in increments of 5. The X-axis is comprised of five different answers, reading from left to right:  Strongly Disagree; Disagree; Neither Agree nor Disagree; Agree; and Strongly Agree. A key at the bottom distinguishes the subject to which respondent was commenting; from top to bottom, it reads as follows: an unfilled box represents the degree to which respondents agree that environmental stewardship has been enhanced; a green and blue horizontal-striped box represents the degree to which respondents agree that visitor experience has been improved; a green diagonal-striped box represents the degree to which respondents agree that maintenance costs have been reduced; a box with green and blue dots represent the degree to which respondents agree revegetation is now more sustainably designed; a green and white diagonal-striped box represents the degree to which respondents agree erosion has been avoided or reduced; and a solid green, filled-in box represents the degree to which respondents agree safety has been improved.

Source: FHWA.

Figure 2. Graph. Degree to which survey respondents agreed with statements about Roadside Revegetation.

The project team used the interview process as a method to gather additional details regarding these six outcomes. In terms of sustainability and environmental stewardship and sustainability outcomes, one interviewee stated that over time, use of native plants increases habitat and promotes natural succession. Regarding maintenance costs, successful native plantings have reduced maintenance costs for many State transportation departments across the country by eliminating mowing and herbicide needs.(31) Interviewees echoed what several survey respondents pointed out: the application of non-native plants is likely less expensive than using natives, but the maintenance of non-native plants is more costly in the long term. One interviewee added, “Upfront costs are more expensive. Nurseries put a lot of care into producing native plants. But they are hardier, and survivorship is much better than when using traditional methods. The short-term versus long-term benefits are compared, using native plants is more worthwhile.14 However, one survey respondent noted that, given funding constraints, revegetation is only done where it is necessary or when funding is available.

Regarding visitor experience, one interviewee noted that sometimes visitor experience anecdotes are used to support funding requests for native revegetation projects. Improving the practice of native revegetation provides visitors with increased viewing and photography opportunities. Another interviewee noted that quick establishment of native revegetation improves public perception of a project, which provides increased community support for similar projects: “Seeing greengrass is better than seeing construction. Because the public may not realize the plants are native species, our agency has made an effort to inform the public about natives, which encourages other agencies to also use them.15

There was less agreement about whether Roadside Revegetation has helped improve safety outcomes. According to one interviewee, while it is important to put the right plants in the right place, there is no correlation between safety and the use of native plants. A majority of survey respondents who answered this question neither agreed nor disagreed with the statement, “Safety has been improved.”

3 See first four entries in appendix C.

4 BLM is the largest native seed buyer in the Western Hemisphere. In 1999, BLM’s purchase of 6.5 million lb of seed was 70 percent non-native. Since the establishment of the Native Plant Materials Development Program, BLM now uses more native seed than not. From 2004 to 2013 BLM purchased more than 15 million lb of native seed and about 10.8 million lb of non-native seed. One of the issues affecting BLM’s purchase of seed for fire rehabilitation, reclamation, and restoration projects is that seed for the desired native species is not always available in the quantity and quality needed. The Native Plant Materials Development Program’s mission is to increase the quality and quantity of native plant materials available for restoring and supporting resilient ecosystems. BLM works with a variety of partners, including Federal, local government, non-profit, and private, to accomplish the steps of the native plant materials development process.


5 See references 19, 21–27, and 20.

6 National University of Mongolia, email to FHWA, May 6, 2015.

7 Korea National Arboretum, email to FHWA, January 8, 2009.

8 Oregon Department of Transportation, email to USFS, June 1, 2015.

9 Washington State Department of Transportation, email to FHWA, November 25, 2009.

10 For more information, see section 2, Telephone Interviews.

11 For more information, see section 2, Telephone Interviews.

12 For more information, see section 2, Telephone Interviews.

13 For more information, see section 2, Telephone Interviews.

14 For more information, see section 2, Telephone Interviews.

15 For more information, see section 2, Telephone Interviews.



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