CHAPTER 4
Linking Roadside Vegetation Asset Management to TAMP and Alternative Strategies

4.1 Introduction

Given that roadside vegetation asset management tasks directly relate to bridges and pavement life cycles and the integrity of other roadside vegetation safety features, it is preferable to link roadside vegetation asset management to the state TAMP. For instance, if vegetation is not managed properly near structural assets (e.g., bridges), the resulting erosion can cause failures. If roadside vegetation asset management assets (e.g., guardrails, culverts, turfgrass, native vegetation, pollinator habitats, and trees) are added to the state TAMP, state DOTs can help mitigate issues with these assets more readily. Including roadside vegetation asset management assets in the state TAMP can provide the impetus for state legislatures to fund work pertaining to vegetation and roadside assets.

Assets within the state TAMP are required to meet asset condition rating requirements. However, many state DOTs do not have a condition rating system for vegetation assets and roadside vegetation safety features. Before vegetation assets and roadside vegetation safety features are added to the state TAMP, rating information for asset conditions must be developed. Ideally, each state will have four to five condition ratings for assets. Example rating conditions are “A, B, C, D, F” or “excellent, good, fair, poor.” Using asset condition naming conventions like those used in the state TAMP for bridges and pavement can lead to easier adaptation. During development, these asset conditions can be reviewed by field staff to ensure that the markers listed in the asset condition rating systems are achievable and on par with the typical goals for vegetation along the right-of-way.

States do not need to use the same asset condition rating system across the country because states have different goals, growing conditions, and vegetation seeded along the right-of-way. Asset conditions for vegetated areas will differ depending on the location and surrounding structural assets (e.g., vegetation management surrounding a guardrail is different from vegetation management within a wetland mitigation area). As a result, asset condition rating information may differ among types of assets.

Three of the five case studies have successfully added assets into their state TAMPs. At the direction of the state legislatureʼs passage of Senate Bill 1, Caltrans included culverts in their TAMP. Following this, Caltrans staff developed an in-house proprietary system to assess asset conditions and track assets across the state. Caltrans maintenance staff then began updating the systems developed for culverts to create a separate system for irrigated landscapes, because the roadside vegetation asset management plan will soon require the inclusion of asset conditions. Caltrans staff determined they would use culverts in developing a system for tracking and assessing the condition of the irrigated landscapes because culverts were the most like irrigated landscaped areas. During this process, similar terminology and condition definitions were used for irrigated landscapes as for culverts, with irrigated landscapes given ratings of “good, fair, poor,” or “other.”

ODOT has included conduits in their state TAMP as discretionary assets. Conduits include both culverts and storm drains. The inclusion of conduits has ensured funding for management of these assets across the state. The rating system for conduits is based on the bridge rating system with ratings from 0 through 9. If the condition is 7 or above, it is considered in good condition; between 5 and 6 means fair condition; 4 or less is considered poor condition.

WSDOT has multiple vegetation assets and roadside safety features within the state TAMP in addition to the federally regulated bridges and pavement. These additional vegetation assets and roadside safety features include but are not limited to roadside vegetative land use (e.g., trees, turfgrass), culverts, signs, roadway delineation, and chronic environmental asset deficiencies (e.g., noxious weeds, tree limbs in need of being removed/trimmed). WSDOT identified outcome thresholds for all assets included within the TAMP. For example, noxious weeds are required to be identified and assessed along the roadway; these assets must be graded “A, B, C, D, or F” based on the percentage of the roadside with noxious weeds in a designated area. This is one of few instances during the case study interviews where a state DOT identified clear markers to rate conditions of vegetation along the right-of-way. WSDOT initially developed the stateʼs asset condition rating system in 1998.

If a state DOT includes roadside vegetation asset management assets in the state TAMP and provides maintenance requirements instead of guidelines, staff can more easily adhere to maintenance requirements if the language mirrors the requirements for federally regulated assets in the TAMP. Whether the state DOT moves toward including roadside vegetation asset management assets in the state TAMP or these assets remain separate within a roadside vegetation asset management plan, ensuring the tools and technology are updated is essential to maintaining the right-of-way. Ideally, central office staff provide requirements to local staff while allowing local staff to provide input in developing the roadside vegetation asset management plan. Local staff will need access to all equipment, tools, and technology needed to complete roadside vegetation asset management tasks—local staff can help map and track these assets.

Vegetation assets could be added to the TAMP to increase the stability of the surrounding structural assets without depleting resources for FHWA-required assets. To ensure structural asset maintenance is not affected and to support the additional staff and personnel hours needed for their inclusion in the TAMP, additional funding may need to be provided for the maintenance of these roadside vegetation asset management assets.

4.2 TAMP Alternatives

The inclusion of roadside vegetation asset management within the TAMP is encouraged; however, a state DOT that does not support the inclusion of roadside vegetation asset management within the state TAMP can still create a fully developed roadside vegetation asset management plan. The roadside vegetation asset management plan can include requirements that must be met with the state DOTʼs goals. However, when pursuing this alternate route, state DOTs need to recognize that (1) the priorities may shift over time and (2) there is a possibility of receiving inadequate funding because assets listed within the state TAMP receive funding priority.

It is important to include rating scales for the included assets in the roadside vegetation asset management plan. Including rating scales or condition ratings for vegetation and safety assets facilitates the stateʼs ability to identify specific goals for these assets, improving the chances of locating and receiving funding for roadside vegetation asset management. If a state DOT decides to add these assets into the state TAMP in the future, the inclusion of rating scales or condition ratings for vegetation and safety assets would make the transition process easier (given that condition ratings are required in state TAMPs).

When developing the roadside vegetation asset management plan, central office staff can provide oversight and minimum management recommendations, with local staff providing input for the full roadside vegetation asset management plan. Regional roadside vegetation asset management plans are beneficial, especially in states that have various climate types. Including field and central office staff in developing a roadside vegetation asset management plan will ensure that the identified work aligns with state goals and can be met with the available staff and equipment levels.

Local staff will need access to all equipment, tools, and technology necessary to complete roadside vegetation asset management tasks to realize the benefits of a roadside vegetation asset management plan. The benefit of including field staff in the use of tools and technology will be seen in the knowledgeable input field staff can provide regarding the roadside assets, both structural and vegetative. States that limit the number and level of staff with access to roadside vegetation asset management data may find roadside vegetation asset management activities taking additional time.

4.3 Adaptable Practices

The following suggested roadside vegetation asset management practices can be implemented regardless of whether they are included in state TAMPs:

• Use similar terminology for structural assets (e.g., bridges and pavements), vegetation assets, and safety features, both within a state DOT and between state DOTs. Consistency in terminology can help reduce the number of software systems for each state DOT and can help state DOTs identify possible roadside vegetation asset management funding sources, given that funding providers may identify roadside vegetation asset management tasks as an essential part of the state DOT maintenance schedule.
• Use mile markers along with GPS points for mapping and tracking progress and completed work. GPS locations of safety features or vegetation assets can become inaccurate following road construction where the road has been relocated.
• Provide staff access to an app on a tablet or similar device that supports the use of GPS points, mile markers, and comments for recording roadside vegetation asset management data.
• Ensure tools and technology are updated at least every 5 years to stay current with advances and support the ability to be updated to avoid software obsolescence.
• Develop staff performance measures for achieving roadside vegetation asset management plan goals. These performance measures can be created with the input of local staff to ensure information accuracy and staff buy-in for the changes being enacted and to help state DOTs create goals for staff performance.
• Use already-established state DOT protocols and processes for structural assets within the state DOT or look to other state DOTʼs protocols and processes that are already established for vegetation assets.
• Ensure all information included with the state TAMP or roadside vegetation asset management plan complies with the state DOTʼs rules and regulations. (Not all terms, definitions, processes, and protocols will be used by multiple state DOTs or assets.)