Executive Summary
A vibrant and well-maintained urban forest provides significant environmental, social, and economic benefits that improve quality of life for residents. Multiple City departments are responsible for maintaining trees under the care and control of the City: Board of Public Works Bureau of Street Services/Urban Forestry Division (Public Works); Department of Water and Power (DWP); and Department of Recreation and Parks (RAP). Collectively, these departments spent approximately $49 million on tree maintenance activities in FY2017-18.
“Street trees” are located in parkways (i.e., landscaped areas between the curb and sidewalk) and median islands. Overgrown or damaged street trees present a public safety risk because they can: (1) impede the public right-of-way; (2) cause harm to pedestrians or property as a result of fallen trees/branches or sidewalks buckled by tree roots; or (3) interfere with power lines.
Although many of these trees are considered to be “owned” by the adjacent property owner, the City is responsible for caring for street trees and ensuring the public right-of-way is clear of tree-related hazards.
The City is falling short on caring for the trees that line our streets.
- In 2015, the City rated the health of the street tree population with a “D” letter grade.
- Approximately 30% of trees in the region are at risk of dying in the coming years due to factors such as drought, disease, and pests.
- Street trees in the City were proactively trimmed on a 14- to 18-year cycle in FY2017-18, urban forestry experts typically recommend a 5-year cycle.
- Public Works proactively trimmed only 43,000 of the City’s 600,000 – 700,000 street trees in FY2017-18.
- On average, the City paid approximately $2.5 million per year in tree-related settlements during the three-year period ending June 30, 2018.
- The City has not conducted a comprehensive street tree inventory since 1996.
Because street trees are such a valuable and visible public infrastructure asset, we reviewed Public Works’ tree maintenance operations. The information and recommendations in this report are intended to assist the City in three critical areas: (1) conducting a citywide street tree inventory; (2) using data to improve street tree maintenance; and (3) potential contracting strategies to meet future needs.
Public Works arborists are responsible for protecting the health of the City’s street tree population and provide a broad range of maintenance services including, but not limited to, tree trimming, removal, emergency response, and clearance of obstructions. In contrast, DWP’s mission is narrow and focused on preventing power disruptions caused by trees near power lines and other equipment.
Many of the same management principles that apply to public infrastructure, such as streets, can be applied to trees. Generally, regular preventive maintenance is more efficient and maximizes the overall value of the urban forest. A tree that is trimmed or inspected annually requires less time and effort than a tree that is trimmed once every decade. Prolonged periods of deferred maintenance increase the likelihood of tree failure or other conditions that require emergency response, which is often more expensive.
Public Works’ ability to effectively maintain street trees has been challenged during the previous decade. Over the course of a four-year period beginning in 2009, Public Works’ street tree maintenance budget was reduced by almost 40% and nearly all proactive street tree trimming was suspended. Between 2010 and 2012, Public Works’ proactive trim cycle exceeded 50 years, which was more than 10 times greater than what is recommended by urban forestry experts. As the City’s financial outlook improved, funding for street tree maintenance has slowly recovered and Public Works has worked to rebuild the City’s proactive tree trimming capacity.
These factors, along with environmental factors beyond the City’s control, are contributing to the continued deterioration of the City’s street tree population. City Policymakers and Public Works have recently taken important steps to overcome these challenges, however, much work Remains.
KEY ISSUES
We found that Public Works needs to revamp its approach to managing street tree maintenance operations. The lack of basic inventory data and outdated management tools prevented our ability to determine whether the program was operating efficiently and effectively. These issues require urgent action so that the City can make informed decisions to reverse ongoing urban forestry trends.
During the FY2018-19 budget cycle, the City Council approved a proposal to eliminate the use of contractors and hire new in-house crews for proactive tree trimming activities. When fully implemented, Public Works projects the five in-house crews will proactively trim approximately the same number of trees as FY2017-18.1
Maintaining the current service level (14- to 18-year trim cycle) is not enough. Moving forward, the City should prioritize proactive trimming as much as possible; it will cost the City less in the long term and allows Public Works arborists and tree surgeons to take actions that prevent emergency situations from occurring. Shifting to an in-house model also provides Public Works managers with increased control and flexibility; different approaches (e.g., prioritizing specific tree species) should be considered and tested to determine whether they increase efficiency.
An urban forestry consultant engaged by City Plants recently completed an assessment of the City’s need for a comprehensive management plan.2 The consultant estimated that overall urban forestry funding (which includes maintenance of street trees) for Public Works and RAP needs to be increased by $40 to $50 million in order to make significant improvements.
As City Policymakers make funding decisions, it should prioritize investment in a citywide street tree inventory and centralized management system so that each additional dollar allocated to the program provides the greatest possible value to Angelenos.
I. Conducting a Citywide Inventory of Street Trees
Street trees, like roadways and sidewalks, are an element of the City’s public works infrastructure and require ongoing planning, maintenance, and improvement. To accomplish this, the U.S. Forest Service and American Public Works Association recommend maintaining an inventory of the street tree population.
Public Works gradually stopped maintaining data collected during the 1996 inventory due to staffing constraints, concerns about data reliability, and the burdensome process of manually inputting information from paper records into an obsolete management system.
To ensure that Public Works can develop appropriate maintenance plans and priorities, it urgently needs up-to-date information about its street tree population such as:
- tree location (GIS-based), species, diameter and height, current condition, maintenance needs and priority level, proximity to other infrastructure; and
- impacts of drought, pests, diseases, and the rates at which dead trees are replaced.
Public Works will need to evaluate inventory development opportunities to determine which approach is best suited for collecting data about the City’s street tree population. First and foremost, Public Works has opportunities to collect important information each time it dispatches in-house crews or outside contractors to perform street tree maintenance activities. There are opportunities to supplement these data collection efforts by using technology-based
and collaborative strategies.
- Advanced remote sensing technologies provide an opportunity to collect data that can be used to develop a street tree inventory. LA County officials are exploring the possibility of a pilot study for a hyperspectral & LiDAR-equipped flight to collect and analyze tree-related information in a limited geographic area. If the project is successful, the City should consider initiating its own flight or partnering with the County, other governments in the region, and non-governmental stakeholders.
- New York City has a street tree population that is similar in size to Los Angeles and its Department of Recreation and Parks (NYC Parks) developed its most recent tree census using a combination of in-house staff and volunteers. Volunteers received training and used mobile applications, online mapping tools, tape measures, and species guides to collect tree data. In total, more than 2,200 citizens donated 12,000 hours to the effort.
- Each year, DWP and Public Works crews inspect and maintain tens of thousands of street trees. The departments carry out their tree-related missions independently from one another, and street tree inventory/maintenance data remains in departmental silos. As Public Works develops its plan for an updated inventory of street trees, it should consider partnering with DWP to compile and share street tree data.
Whichever approach is selected, the City needs to engage in careful planning, execution, and monitoring of the effort.
To address these inventory issues, Public Works should:
- Develop a plan to implement a comprehensive street tree inventory system that will support future tree maintenance, planting, removal, and pest and disease mitigation activities.
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- Consider using existing software packages that can provide a cost-effective solution
for the necessary data platform, and can leverage mobile technology to support field-based input; and updates and support time/labor input and activity tracking to help identify resources spent on various maintenance activities.
- Consider using existing software packages that can provide a cost-effective solution
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- Present the implementation plan, recommended platform, and anticipated costs to
policymakers and stakeholders to help garner support for its success.
- Present the implementation plan, recommended platform, and anticipated costs to
- Assess the feasibility of:
- Implementing technology-based strategies (i.e., hyperspectral imaging and LiDAR) to collect street tree inventory data;
- Partnering with volunteers/other stakeholders and using mobile technology to develop a street tree inventory program; and
- Improving coordination with DWP to share street tree data.
- Conduct an updated inventory of street trees to account for changes that have occurred
since the last citywide inventory was performed in 1996. - Improve processes related to the ongoing collection, monitoring, and management of street tree data to ensure the comprehensive inventory system remains a dynamic, up-to-date resource for Public Works to make informed decisions.
II. Using Data to Improve Street Tree Maintenance
Public Works managers indicated that staff used an in-house system for inventory and work order management until approximately 2011. However, the system was obsolete because it did not integrate with mobile devices and allow crews to update inventory and maintenance records while working in the field. Currently, Public Works staff use a combination of paper logs and decentralized tracking systems.
Using a centralized, electronic management system would allow Public Works to improve its operational efficiency and make it easier to track critical information about street tree health and maintenance activities. RAP has made significant progress on this issue and Public Works should consider a similar approach.
An integrated forestry management system becomes increasingly important when resources are limited. Given that the City’s street tree maintenance program has been generally reactive in nature, monitoring data would provide current information about conditions in the field and improve Public Works’ ability to prioritize specific tree species or locations.
To address these data management issues, Public Works should:
- Develop and implement a centralized system to manage its street tree maintenance operations. At minimum, the system should perform the following functions.
- Integrate work order and inventory management functions in order to streamline
tree maintenance and inventory data collection. - Provide dynamic inventory and maintenance reporting capabilities, so that
managers can use tree data to prioritize maintenance and other urban forestry
improvement projects.
- Integrate work order and inventory management functions in order to streamline
III. Potential Contracting Strategies to Meet Future Needs
Public Works is in the process of shifting to an in-house model for proactive tree trimming, however, future needs may compel the City to consider a hybrid approach using some contractors. Should this scenario emerge, the City should leverage inventory and maintenance data to consider a different contracting approach than it has used in the past.
The City’s contracts for proactive street tree trimming paid contractors a flat rate, whereas some municipalities use a tiered pricing structure that is designed to align unit prices with the specific service being performed (e.g., trimming a palm tree). Setting stipulated prices based on the type or level of service, as well as having a group of pre-qualified contractors ready to perform ondemand or specialized services, may benefit the City.
To address these contracting issues, Public Works should:
- Consider different contracting strategies if City crews need to be supplemented by outside
contractors in the future.- Develop a pool of pre-qualified contractors that can supplement City crews for ondemand services with stipulated pricing for specific types of trimming services.
- Determine whether a service-specific, multi-tiered pricing structure would be more
beneficial to its overall strategy to maximize proactive trimming services citywide.
CONCLUSION
The health and sustainability of the City’s street trees are threatened, and resource constraints have limited the ability to perform proactive maintenance activities within recommended timeframes. These factors place increased importance on how Public Works makes decisions about which trees are prioritized for trimming, removal, planting, and health mitigation activities.
The City should prioritize completion of the first comprehensive inventory of street trees since 1996 and implement a centralized management system to guide Public Works’ day-to-day operations. Successful implementation of these core elements will improve the City’s ability to develop effective long-term strategies that ensure Angelenos will enjoy the benefits of a vibrant and well-maintained population of street trees.
We would like to thank the Board of Public Works and staff from other City departments for their time and expertise during this review. 3
1 Public Works’ projection includes trees trimmed using overtime funds authorized by the Council.
2 City Plants is a public-private partnership between the City, local non-profit organizations, community groups, residents, and businesses.
3 A draft of this report was provided to Public Works on October 29, 2018 and we met with Public Works management at an exit conference on November 15, 2018. We considered their comments as we finalized this report for issuance. Public Works’ formal response and action plan are included as an appendix to this report.