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Suggested Citation:"Chapter 2 - Literature Review." National Academies of Sciences, Engineering, and Medicine. 2019. Landscape Development and Management Practices for Urban Freeway Roadsides. Washington, DC: The National Academies Press. doi: 10.17226/25508.
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Suggested Citation:"Chapter 2 - Literature Review." National Academies of Sciences, Engineering, and Medicine. 2019. Landscape Development and Management Practices for Urban Freeway Roadsides. Washington, DC: The National Academies Press. doi: 10.17226/25508.
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Suggested Citation:"Chapter 2 - Literature Review." National Academies of Sciences, Engineering, and Medicine. 2019. Landscape Development and Management Practices for Urban Freeway Roadsides. Washington, DC: The National Academies Press. doi: 10.17226/25508.
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Suggested Citation:"Chapter 2 - Literature Review." National Academies of Sciences, Engineering, and Medicine. 2019. Landscape Development and Management Practices for Urban Freeway Roadsides. Washington, DC: The National Academies Press. doi: 10.17226/25508.
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Suggested Citation:"Chapter 2 - Literature Review." National Academies of Sciences, Engineering, and Medicine. 2019. Landscape Development and Management Practices for Urban Freeway Roadsides. Washington, DC: The National Academies Press. doi: 10.17226/25508.
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Suggested Citation:"Chapter 2 - Literature Review." National Academies of Sciences, Engineering, and Medicine. 2019. Landscape Development and Management Practices for Urban Freeway Roadsides. Washington, DC: The National Academies Press. doi: 10.17226/25508.
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Suggested Citation:"Chapter 2 - Literature Review." National Academies of Sciences, Engineering, and Medicine. 2019. Landscape Development and Management Practices for Urban Freeway Roadsides. Washington, DC: The National Academies Press. doi: 10.17226/25508.
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Suggested Citation:"Chapter 2 - Literature Review." National Academies of Sciences, Engineering, and Medicine. 2019. Landscape Development and Management Practices for Urban Freeway Roadsides. Washington, DC: The National Academies Press. doi: 10.17226/25508.
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Suggested Citation:"Chapter 2 - Literature Review." National Academies of Sciences, Engineering, and Medicine. 2019. Landscape Development and Management Practices for Urban Freeway Roadsides. Washington, DC: The National Academies Press. doi: 10.17226/25508.
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Suggested Citation:"Chapter 2 - Literature Review." National Academies of Sciences, Engineering, and Medicine. 2019. Landscape Development and Management Practices for Urban Freeway Roadsides. Washington, DC: The National Academies Press. doi: 10.17226/25508.
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Suggested Citation:"Chapter 2 - Literature Review." National Academies of Sciences, Engineering, and Medicine. 2019. Landscape Development and Management Practices for Urban Freeway Roadsides. Washington, DC: The National Academies Press. doi: 10.17226/25508.
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Suggested Citation:"Chapter 2 - Literature Review." National Academies of Sciences, Engineering, and Medicine. 2019. Landscape Development and Management Practices for Urban Freeway Roadsides. Washington, DC: The National Academies Press. doi: 10.17226/25508.
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10 The literature review for this synthesis covers the issues within the project scope. Several of the sources reviewed describe sustainable landscape development and maintenance prac- tices for the urban environment, the use of an integrated vegetation management approach to roadsides, establishment of cooperative agreements, management of illegal or unauthorized use of the ROW, and protection of maintenance workers. However, very little documenta- tion exists that specifically addresses the issues for high visibility urban freeways with limited pedestrian access, such as wider medians, interchanges, and overpasses. The majority of refer- ences to urban conditions were in the context of urban arterials and collectors, streetscapes, and complete streets. Sustainable Urban Landscape Development and Maintenance The UFR is a difficult and unique environment to design for and sustain at the level required for these highly visible locations. These roadsides are more prone to ecological, physical, or social disturbances than other state lands. Local stakeholders can often influence their design, establish- ment, and maintenance. Disturbances within the UFR are more intense, frequent, varied, ubiqui- tous, and disruptive than disturbances typically experienced by other state lands (Robertson and Smith 2011). The construction of a roadway can be in direct conflict with developing a healthy roadside environment able to sustain vegetation. From an engineering perspective, the road base and associated embankments need to be compacted to meet state DOT standards. Depending on the soil’s plasticity index (PI), the typical range of compaction is between 95% and 98%. The residual soils can be inhospitable for planted vegetation. Table 1 shows the comparative soil physical, chemical, and biological properties affected by highway construction. The post-construction soil structure and health require amendment to enable a sustainable plant community that can perform necessary UFR functions. As intensified land use increases in the urban environment, so does the need for using the environmental processes found in self- sustaining and self-sufficient plant communities flourishing on their own outside the ROW. In urban situations, the larger ROW areas within interchanges are often used for material stock- piles, equipment storage, and servicing (Jones et al. 2007). Figure 7 demonstrates the inherent problems associated with providing a suitable area for landscape development within the UFR. These same highly structured and manipulated embankments, interchanges, frontage roads, overpasses, and large median areas are the available locations for landscape development in limited access UFR. The UFR needs to be a low maintenance, aesthetically pleasing roadside that is acceptable to stakeholders, end-users, and entities tasked with maintenance. The available locations for landscape development are often minimal at best. C H A P T E R 2 Literature Review

Literature Review 11 The Tennessee DOT Landscape Design Guidelines suggest asking the following questions during the design development process (Camp et al. 2010): • What are the available staff, equipment, and funding resources for maintenance? • What level of maintenance will be required to maintain the landscape to meet safety require- ments (clear zone, sight lines, etc.)? • What level of maintenance will be required to maintain the landscape to achieve the intended function and project goals? The planning, design, and maintenance issues for the UFR are numerous and considerations include roadside performance and function as well. These can include, but are not limited to, the following: • Access for maintenance personnel and equipment • Adjacent land uses • Air pollution and particulate deposition • Carbon sequestration • Cooperative development and maintenance agreements Undisturbed Soil Post-Construction Soil 40 % to 55% Compaction 95% to 98% 1.1 to 1.4 g/cc Bulk Density 1.5 to 2.0 g/cc Aggregate Stability Decreases Porosity Reduced Adequate Organic Matter Reduced or Absent Present and Active Micro-organisms Reduced 35% Stormwater Infiltration 15% 15% Stormwater Runoff 55% to 70% Water-holding Capacity Reduced Available Water Reduced Yes Available Nutrients Very Reduced pH Altered Electrical Conductivity Reduced Cation Exchange Capacity Reduced Rooting Penetration Resistant Table 1. Impacts of highway construction on soil properties (Jones et al. 2007). Figure 7. Typical urban ROW construction areas.

12 Landscape Development and Management Practices for Urban Freeway Roadsides • Cost-effectiveness • Disturbances caused by roadway repair, renovation, and expansion • Effects of de-icing agents, snow storage, and ice • Effects of structure shadowing • Erosion control • Fire risk • Fixed object issues • Graffiti opportunities on roadside art, retaining walls, noise barriers, and other structures • Headlight glare reduction • Heat island effects of pavements, structures, and buildings • Highway alignment and design speed • Illegal or unauthorized use of the ROW • Integration of historic, cultural, and scenic themes • ITS technology placement, usage, and maintenance • Lighting • Multimodal accommodations • Noise and vibration • Noxious and invasive weed management • Outdoor advertising and other signage • Plant species selection—native and adaptable • Roadside appurtenances • Safe access for maintenance workers • Safety clear zone • Sight distance • Soil requirements for pavement, subbase drainage, and other infrastructure • Soil requirements for sustainable landscape development • Stakeholder expectations • Stormwater management for quality and quantity • Traffic volumes • Utilities • Views and screening • Visual complexity • Water and resource conservation • Windbreak protection (New York State Department of Transportation 2013, Jacobs et al. 2002, Arizona Department of Transportation 1988, California Department of Transportation 2016, Texas Department of Transportation 2017) Instead of trying to accomplish a statewide approach to landscape development, the Nevada DOT (NVDOT) developed a series of corridor master plans. Many of these discuss the UFR applications. The individual plans contain recommendations for various corridors throughout the state regarding the following: • Guidelines for the design of highway facilities including themes, levels of treatment, cost goals, and priorities for further development, design, and construction • ROW design and planning guidelines • Cooperative planning in association with local governments along each corridor • Continuing community involvement • Long-range, cost-effective solutions to solve operation and maintenance issues The corridor plans include the following: • I-15 • I-80 and Northern US 95

Literature Review 13 • US 93, East US 6, and East US 50 • Central US 95, West US 6, and Central US 50 • Southern US 95 and US 93 • US 395, West US 50, SR 28, SR 207, and SR 431 (Nevada Department of Transportation 2017) More recent components of the UFR are the placement of and maintenance requirements for ITS technology, and the potential affects ITS may have on UFR design and maintenance. As the Internet of Things, Smart Cities, automated and connected vehicles, and other ITS technologies grow, so will their presence within the ROW. Florida DOT (FDOT) includes provisions in its documents that directly address ITS. Landscape development and maintenance plans require that plant materials used be compatible with existing and proposed ITS devices and above- and belowground utilities. The designs must also consider size at maturity to ensure they will not block visibility to signs, ITS cameras, sight lines, and so forth. The use of as-built plans can deter- mine accurate locations for ITS and utility components (Florida Department of Transportation 2018, Florida Department of Transportation 2015). The process for achieving a balance between community requests and a sustainable landscape development starts early in the project planning stages. The use of CSS addresses coordination among stakeholders during the planning and design process. This is particularly useful in the UFR environment. Urban Integrated Vegetation Management Plans Implementation of integrated vegetation management (IVM) plans has proliferated through- out state DOTs. The concept is a “coordinated decision-making and action process that uses the most appropriate and effective vegetation management methods and strategies, along with a monitoring and evaluation system, to achieve roadside maintenance program goals and objec- tives in an environmentally and economically sound manner” (Robertson and Smith 2011). The IVM methodology uses many approaches including cultural, mechanical, structural, bio- logical, and chemical practices. For the UFR, treatments are determined according to specific site conditions that can include the level of maintenance required, vegetation types, and extent of landscape development, presence and type of noxious and invasive plants, safe, reasonable, and practical accessibility for equipment and workers, proximity to public spaces, and adjacent land uses. Robertson and Smith’s Sustainable Roadside Design and Management for Urban Freeways in Western Washington identified two specific key issues for the UFR: (1) the presence of noxious and invasive plants and (2) illegal use of the ROW. Implementation of IVM starts early in the planning and design process and is facilitated through communication among those associated with the design, construction, and mainte- nance of the UFR. The design and maintenance staff need to work in concert from the early stages of planning and design to prioritize the levels of maintenance required for specific UFR sites. Training for personnel associated with the UFR is crucial for understanding the design intent, function, and goals; performance expectations and capabilities; and importance of IVM for achieving a healthy, sustainable urban roadside (Robertson and Smith 2011, Berger 2005). Nowak and Ballard proposed a six-step system, shown in Figure 8, as a framework for the cycle of activities needed to guide those stakeholders and managers tasked with communicating, organizing, and conducting an IVM plan (Nowak and Ballard 2005). In NCHRP Synthesis 341: Integrated Roadside Vegetation Management, DOTs in the United States and Canada were surveyed to determine the state of the practice for IVM (Berger 2005). The use of local and regional resources for those tasked with roadside management can be beneficial in meeting maintenance needs. The other take away from this synthesis is that one

14 Landscape Development and Management Practices for Urban Freeway Roadsides size does not fit all. IVM practices work well when applied to regional conditions. Berger (2005) did not specifically address the UFR environment in this synthesis; however, many of the concepts discussed are applicable to the UFR. The Oregon DOT (ORDOT) adopted water conservation techniques for roadside irrigation to comply with the Oregon Sustainability Act (State of Oregon 2017). Irrigation systems incor- porate “smart” controllers and sensors to meet plant needs and have rapid response for irriga- tion system malfunctions to avoid wasting water on leaking systems. (Oregon Department of Transportation 2018). Caltrans has implemented similar techniques by using non-potable water for irrigation in many locations to meet expectations of the Executive Order B-37-16, Making Water Conservation in California a Way of Life. A memorandum issued to Caltrans in 2016 included the following compliance goals: • Implement practices to continue to meet our 50% water use reduction goal compared to 2013 usage. New planting added to the state ROW may modify this goal in some districts. • Implement policies and practices to expedite converting our irrigation systems to non- potable water sources, with a goal of 100% conversion to non-potable water by 2036 (California Department of Transportation 2016). Illegal or Unauthorized Use of Urban Roadsides The illegal or unauthorized use of state-owned ROW has become a greater focus of state DOTs, in particular within the UFR. Robertson and Smith identified the incursion of illegal or unauthorized use of the ROW as one of state DOTs’ major problems. Of the 12 urban sites studied, six had problems with illegal or unauthorized occupation. Robertson and Smith Figure 8. Six-step IVM plan process cycle (Nowak and Ballard 2005).

Literature Review 15 determined that the preferred areas are flatter, heavily vegetated roadsides, located at large intersections, secluded (not visible from freeways, on- and off-ramps, or adjacent properties), and where there is easy access to food and drink services. Less commonly occupied locations are on steep slopes immediately adjacent to busy freeways. Consider the impacts of potential ille- gal or unauthorized uses of urban roadsides with regard to functional design solutions, visual surveillance, and maintenance regimes early in the UFR design process (Robertson and Smith 2011). Figure 9 shows examples of illegal or unauthorized occupation of the UFR. For many states, management of illegal or unauthorized use of the ROW in urban areas is at the municipal level through local policing and enforceable ordinances. The social, political, safety, and public health issues associated with these illegal or unauthorized uses are ever increasing and far-reaching. Concerns for state DOTs include the following: • Safety, including that of motorists and other users of state DOT facilities, state DOT personnel, and the illegal or unauthorized occupants themselves • Damage to public structures, land, and landscaping • Debris and unsanitary conditions, including an accumulation of hazardous waste that is costly to remove • Displacement of intended users and users with behavior that disrupts the activities for which the site was originally developed • Theft of supplies and equipment (Bassett et al. 2012) Because of the high visibility associated with the UFR, Bassett et al. suggest soliciting partner- ships or relationships with adjacent businesses and residents, local elected officials or their staff, other interested groups, and the media. These relationships may provide assistance with public relations. Research by Chamard (2010) details some approaches to solving issues related to illegal or unauthorized uses that are applicable to the UFR. Changing the physical environment by clear- ing overgrown vegetation provides law enforcement safer access and removes potential shelter areas, by making the area less attractive for illegal or unauthorized use of the ROW. Clear- ing the overgrown vegetation along an Interstate in San Diego resulted in a reduction in calls- for-service, crime, out-of-service time for law enforcement, citations, arrests, and community complaints. An area known for illegal and unauthorized ROW usage in Anchorage, Alaska, showed similar results after the removal of low-growing vegetation. Clearing vegetation may take coordination with other agencies and communication with adjacent land users, and it is a reactive solution. The proactive approach comes through planning and designing the UFR to minimize problematic areas. Figure 9. Illegal or unauthorized occupation within UFR (Courtesy of WSDOT).

16 Landscape Development and Management Practices for Urban Freeway Roadsides Disbanding established illegal or unauthorized occupation of the ROW is effective and requires planning and specific protocols for such action. Chamard outlines the following steps for this process: • Establish a memorandum of understanding (MOU) specifying which agency is responsible for law enforcement, safety, and environmental protection, and their role in implementation. • Provide all illegal or unauthorized occupants with a written notice advising the following: – Their actions are in violation of the law – Remaining occupants are subject to further law enforcement – Alternate shelter location arrangements are available – Specific date by which occupants must vacate the area • Return to the area of occupation and issue citations to those remaining at that location after the date of vacation passes. Inform them of the date by which they must vacate and that they will be subject to arrest and seizure of property if they do not leave by then. • Use available law enforcement agencies (state DOTs are not law enforcement agencies) if necessary, to remove those remaining at the property post-evacuation date and store their belongings. – Other agencies or government departments may be required to remove personal property. – Ensure that there are no constitutional violations regarding searches of property. • Establish another MOU detailing the parties responsible for ensuring that the illegal or unauthorized use does not return. – Consider having each agency contribute some resources for regular patrols of the affected areas. – Ensure there is the capacity to clean up an area if reestablishment occurs. • Routinely remove vegetation that provides a screen for the potential occupation of areas. • Post signage in the former illegal or unauthorized occupation area indicating that camping is not permitted in the area (Chamard 2010). Figure 10 shows an example of deterrent signage on structures from WSDOT. Many state DOTs are recognizing that the illegal or unauthorized use of the ROW has numer- ous difficult issues, and many of these are highly sensitive. The Landscape Design Guide of the Maryland DOT State Highway Administration (MDOT SHA) calls for using the principles of CPTED to avoid designs that create hazards or provide refuge (Maryland Department of Transportation State Highway Administration 2016). This collaborative process mirrors CSS by including “relevant stakeholders to a specific project; owners, architects, engineers, planning and land use boards, law enforcement officials, security professionals, and citizens working together Figure 10. Deterrent posting on structures (Courtesy of WSDOT).

Literature Review 17 to ensure that the built environment maximizes desirable use of the property while simultane- ously impeding potential undesirable use and opportunities for criminal activity” (Connecticut Housing Finance Authority 2017). CPTED typically refers to the planning, design, and mainte- nance of housing areas; however, the use of CPTED has application for the UFR environment as a deterrent for illegal or unauthorized uses of the ROW. Deterrents are most effective when considered early in the design process. The TxDOT’s Landscape and Aesthetic Design Manual addresses deterring vandalism and unauthorized use of irrigation systems. The manual states that irrigation systems in areas “not visible from routine traffic or those which have structures like bridges or culverts that provide shelter in inclement weather should have no above ground parts and include lockable covers on valves to discourage vandalism by persons using the water for drinking or bathing.” The manual further states not to use brass valves and nozzles due to the historically high incidence of theft for salvage value (Texas Department of Transportation 2017). Arizona DOT (AZDOT) states in its Right of Way Procedures Manual that it “as an owner of public lands, reserves the right to protect itself and the public from unauthorized use of its property. In the interest of public health, sanitation or quiet enjoyment, it is necessary from time to time to take the actions . . .” AZDOT may post “No Parking” and “No Trespassing” signs. AZDOT relies on the local city police department for enforcement (Arizona Department of Transportation 2016). The Minnesota DOT (MnDOT) Policy OP014 Unauthorized Encampment Removal from MnDOT Property outlines procedures for effective, humane, and environmentally sound removal of unauthorized encampments from MnDOT-managed state-owned property. MnDOT defines an unauthorized encampment as “a site on MnDOT Property where one or more persons use the property for a non-transportation purpose including, without limitation, preparing meals, storing personal belongings, or sleeping. Unauthorized encampment includes illegal use of rest area property” (Minnesota Department of Transportation 2018). The ORDOT 734-020-0095 Prohibited Activities on State Highway Right of Way states that camping or staying overnight, or any establishment of occupancy or of a residence, whether temporary or permanent, and the erection of any building or facility, including but not limited to tents, shacks, lean-tos, stands, or shelters of any kind are prohibited. Violation of these rules may lead to citation for criminal trespass under the laws of this state (Oregon Department of Transportation 1981). The Pennsylvania DOT (PennDOT) Maintenance Manual contains a section titled the Relocation of Human Beings. “When other circumstances exist, assistance should be sought through the County’s Department/Office of Human Services. If it is determined that PennDOT will assist with the relocation, the appropriate local or State Police shall be asked to provide a protective escort. PennDOT may assist with disposing of debris on the right-of-way that the County’s Department/Office of Human Services does not clear from the site” (Pennsylvania Department of Transportation 2012). Damage to the UFR can range from destruction of vegetation and irrigation systems to pilfer- ing technology and infrastructure located on site. Damage to traffic control components, ITS technology, closed-circuit television (CCTV) cameras, public property, and other associated problems can be costly for state DOTs. Figure 11 shows damage to a control cabinet. Managing the UFR for illegal or unauthorized uses of ROW is relevant for many state DOTs. Sustainable landscape development and maintenance includes effective deterrents and other management methods for illegal occupation and other unauthorized ROW uses. Although this is an ever-growing issue in the urban ROW environment, few state DOTs have addressed a

18 Landscape Development and Management Practices for Urban Freeway Roadsides solution through an official policy or procedure. Many rely on local governmental agencies for authority and enforcement. Using trespass law is a practicable method for discouraging the establishment of illegal occupants within the state DOT-owned ROW. “For DOTs, the issue of trespass is particularly difficult to enforce, as the property is publicly owned. However, in some cases, particularly for properties not intended for regular access by the public, some restric- tions may be possible. Public agencies have begun to enact trespass laws that only prohibit certain specific actions (e.g., sleeping) or prohibit them only at specific times (e.g., overnight). Such laws can be enforced using signage that references the local statute or ordinance, which is less resource-intensive and can give law enforcement more discretion” (Bassett et al. 2012). Appendix D contains examples of state DOT policies, procedures, and practices for illegal or unauthorized use of the ROW. Work Zone Safety for Urban Roadsides In the NCHRP Synthesis 509: Highway Worker Safety, Gambatese et al. (2017) identified five common factors as areas or situations in which workers operate at the highest level of risk (see Figure 12). Workers maintaining the UFR routinely meet all the identified risks: • Urban locations • High average daily traffic • Vehicle parked on the shoulder • Roadside work near the shoulder • Employee on foot (Gambatese et al. 2017) The Georgia DOT (GDOT) turned to social media to improve its worker safety. Not only does it issue press releases regarding work zone safety, GDOT uses Facebook and Twitter to get the message to the public. The following is the GDOT press release Roadside Vegetation Management Work Continues in Pickens dated Tuesday, January 31, 2017: JASPER, Ga. - As part of its integrated roadside vegetation management program, Georgia DOT routine maintenance crews resume today their work on trimming overgrown vegetation along State Route (SR) 515 in Pickens County. Work will proceed daily Tuesday through Friday between the hours of 7:30 a.m. and 5:30 p.m., weather permitting. Integrated roadside vegetation management is a method to bring together social and cultural elements, biological concerns, and mechanical treatments to economically manage roadsides for motorist safety, environmental health and visual quality. Figure 11. Damage to state DOT property within UFR (Courtesy of WSDOT).

Literature Review 19 Each day, hundreds of Georgia Department of Transportation employees and contractors work on dozens of highway, bridge and intersection improvements throughout the state. Their work often brings them and heavy machinery in close proximity to travel lanes. Fifty-seven Georgia DOT personnel and many more motorists, passengers and contractors’ workers have been killed in highway work zone accidents since 1973. Please help us prevent these tragedies by slowing down; being especially attentive and cautious as you pass through construction work zones; and always driving responsibly. Safer Driving; Safer Work Zones; For Everyone. For information on the Department of Transportation, visit http://www.dot.ga.gov. You also may follow us on (www.facebook.com/GeorgiaDOT-Northwest) and Twitter (https://twitter.com/GDOTNW) (Georgia Department of Transportation 2017). Many state DOTs have some sort of criteria for work zone safety and associated specifica- tions and plans. Few have these for landscape maintenance workers. The Hawaii Department of Transportation’s (HDOT’s) Highway Manual for Sustainable Landscape Maintenance contains a chapter entitled Safety and Temporary Traffic Control in the Landscape Maintenance Zone. This chapter outlines procedures for landscape maintenance and provides diagrams for traffic controls for landscape maintenance (Hawaii Department of Transportation 2011). The MDOT SHA addresses maintenance worker safety in their Landscape Design Guide (Maryland Department of Transportation State Highway Administration 2016). Designers follow plant materials setback distances “to reduce vegetation growth into shoulder or travel lanes, to reduce sightline impacts, or to avoid conflicts with maintenance operations.” Figure 13 shows an example of design criteria that incorporates maintenance worker safety. Examples of UFR worker safety documents are in Appendix E. Cooperative and Partnering Agreements The use of local and regional sources can mitigate the burden of maintaining the UFR. The types of cooperative agreements identified by Williams in NCHRP Synthesis 337: Cooperative Agreements for Corridor Management consist of resolutions, MOUs, intergovernmental agree- ments, and public-private agreements. Of these agreements, the MOU was the most common type used. Maintenance agreements for utilities and landscaping were the most common type of intergovernmental agreements. Public-private agreements mainly dealt with access, easements, landscaping, joint occupancy of public ROW, and maintenance. The public-private agreement Figure 12. Maintenance workers within the UFR (Courtesy of WSDOT).

20 Landscape Development and Management Practices for Urban Freeway Roadsides may require landowners or developers to contribute to the services and resources needed as a result of development (Williams 2004). The Scan Team Report: Leading Practices in Large-Scale Outsourcing and Privatization of Maintenance Functions (NCHRP Project 20-68A, Topic 11-01) investigated state DOT mainte- nance activity methods (Duncan et al. 2014). Although roadside maintenance was not a focus, Duncan et al. did find that outsourcing some roadside maintenance activities was a lower cost to state DOTs. The study stated that WSDOT contracts out specialized work and infrequently performed tasks (e.g., large tree removal in particularly challenging locations) that are not cost- effective for state DOT staff to perform. Volunteer groups and prisoners used by other agencies perform unskilled maintenance tasks such as litter removal. TxDOT engages in state use con- tracts with persons with disabilities for highway maintenance services such as litter pickup and removal, mowing, tree trimming, picnic and rest area maintenance, metal beam guardrail repair and replacement, and landscape maintenance (Duncan et al. 2014). Several state DOT documents, policies, or agreements pertain to cooperation agreements between the DOT and other entities for the cost sharing and maintenance of landscape develop- ment, particularly in the UFR environment where landscape development typically requires a higher level. Some state DOTs will only establish vegetation required to meet regulatory compliance for site stabilization or minimal landscaping and will not proceed with any type of ornamental landscape development unless there is an agreement in place for perpetual maintenance of the site. Georgia, Illinois, Ohio, Minnesota, and Wyoming are among those states that require some level of maintenance agreement prior to any landscape development. These agreements include a plan for maintenance work to ensure an acceptable level of maintenance of the site (Georgia Department of Transportation 2011, Illinois Department of Transportation 2010, Ohio Department of Transportation 2017, Minnesota Department of Transportation 2017). Alabama, Ohio, Oregon, Pennsylvania, Virginia, and Wyoming have similar agreement policies for maintenance of the ROW by a local governmental agency, private parties, and volunteer groups (Alabama Department of Transportation 2017, Oregon Department of Transportation 2001, Pennsylvania Department of Transportation 2018, Virginia Department of Transportation Figure 13. Landscape development considerations for worker safety (Maryland Department of Transportation State Highway Administration 2016).

Literature Review 21 2016, Wyoming Department of Transportation 2009). Ohio states that communities conducting maintenance on the ROW without obtaining the necessary permit can be held liable and be made to perform restitution (Ohio Department of Transportation 2017). Georgia requires a limited landscape agreement if a “group or business proposes to mow a limited section of the rights of way adjacent to their frontage, exclusive of any landscape enhancement” (Georgia Department of Transportation 2011). Figure 14 shows a joint participation agreement (JPA) partnering project between Seminole County, Florida, and FDOT District 5 in Casselberry, Florida, designed by AECOM. Examples of cooperative agreements are in Appendix F. Figure 14. Joint participation agreement project in Casselberry, Florida (Courtesy of AECOM).

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Current practices used by state departments of transporttion to design and manage the urban freeway roadsides (UFRs) environment is the focus of National Cooperative Highway Research Program (NCHRP) Synthesis 539: Landscape Development and Management Practices for Urban Freeway Roadsides.

The urban freeway roadsides (UFRs) for this synthesis are those roadsides associated with high visibility urban freeways with limited pedestrian access, such as wider medians, interchanges, and overpasses.

The UFR is part of a greater urban environment with broad social, political, economic, and environmental implications for management. There are numerous UFR stakeholders, such as their respective municipalities, residents, adjacent landowners and businesses, traveling public, and state DOTs, and each has specific requests, requirements, and considerations. Among these are an acceptable level of maintenance and stakeholder expectations for aesthetics.

State departments of transportation (DOTs) recognize their roadway systems are assets that need management and acknowledge that pavements and other infrastructure routinely require resurfacing, restoration, and rehabilitation because their integrity degrades over time. However, the UFR and its respective urban freeway systems may not receive the same routine restoration. The vegetation installed at the time of roadway construction ages with the surrounding infrastructure. Decades after initial installation within the UFR, transportation agencies have mature landscapes that may be near the end of their life cycle.

The inability to adequately access and maintain these areas can result in failure of planted vegetation, loss of investment, and public criticism of state DOTs. The UFR is part of state DOTs’ highway system investment facing many challenges as freeway renovations and expansions encroach on limited right-of-way (ROW) areas available for landscape development. As the size of these areas decreases, so does the ability of maintenance workers and equipment to safely access and maintain them.

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