4.1 Introduction to Life Cycle Management

All transportation infrastructure assets have a life cycle, which includes several stages from initial construction to removal or replacement (see figure 4.1). Life cycle management is an investment approach that considers maintenance, renewal, replacement, or repair options through an asset’s service life with the intent to maximize the benefit provided by the asset at the minimum practicable cost. It employs data on asset condition, treatment options, costs, deterioration rates, replacement cycles, and other factors to evaluate trade-offs between possible investment strategies and treatment timings. Effective life cycle management requires knowledge of the agency’s strategic priorities and an understanding of the performance criteria driving investment decisions, so the right management strategy can be identified and implemented for each asset class. Aligning asset management measures with agency priorities ensures the investments made to extend asset service life provide the maximum impact to the agency’s long-term goals.

Figure 4.1 illustrates a variety of interventions that occur over an asset life cycle. The larger circles represented in the figure are service life altering, and represent a capital investment in infrastructure. Capital investments provide significant life extension, and may alter or enhance the operational nature of the asset, e.g. expand capacity, without fully replacing the asset. Maintenance (reactive, interval based and routine) activities are required throughout the life cycle to ensure the asset achieves its service life.Preservation treatments restore condition or performance to achieve service life, and may extend service life as well, but do not significantly alter the operational nature of the asset. Some agencies may capitalize investment in these preservation activities; however, regardless of the timing and character of the selected interventions, all of them are part of the life cycle management process. More (lower cost) maintenance interventions can offset the number and cost of the larger (and more costly) interventions. Balancing the right intervention, at the right time, can greatly reduce the overall investment needed for infrastructure to be reliably available for providing service.

Life cycle management can be used at both network level and at project level. At network-level, life cycle management considers the needs of an entire asset class, as well as the available funding, to determine the most appropriate life-cycle strategies. For example, analysis can establish the optimal proportions of overall investment that should be allocated to different types of interventions over the network, to minimize investment to achieve performance targets or an average condition level. At a project level, life cycle management is commonly used to develop asset-specific strategies. Project level life cycle plans provide input into the network level life cycle plans. Large bridges or other distinct network components are often planned and managed in this manner.

Life Cycle Cost Analysis (LCCA) is an engineering-economics approach that can be used to quantify the differential costs of alternative design approaches. Network level life cycle management, while a more wholistic process that manages every stage of an asset’s life, may employ LCCA or other forms of analysis to inform management decision-making. Figure 4.2 highlights some of the major differences between life cycle management and life cycle cost analysis. At the network level, LCCA can be used to understand how to best manage the network as it ages. At a project level, it is used to understand what are the most effective actions to be taken on the assets within the project scope at the time of project delivery. Both network level and project level analyses contain many aspects of engineering economic analysis, such as consideration of user benefits, user costs, and the time-value of money to identify alternatives that represent the lowest practicable life cycle cost over the analysis period to achieve the desired objectives.

Decision Making Context

Life cycle management is driven by the need for owners to provide consistent service to those that use the transportation system with the resources available. Infrastructure decision making can take place at several levels within an organization, and in each case, considers different but often interrelated factors. These are illustrated in table 4.1.

Table 4.1 - TAM Decision-Making Contexts
Key Questions and Connections to Other Chapters

Establishing Desired Levels of Service

Before a whole-life strategy can be developed and implemented, an agency must determine what they seek to achieve. In many transportation agencies, the desired level of service (or asset management organizational objectives, in ISO 55000 terminology) provides the linkage between what the goals of an agency are, and what investments and interventions should take priority when managing assets. High level goals should directly influence investment choices when resource allocation decisions are made. Service levels help establish when gaps need closing to achieve a goal, and merits investment. Chapter 2 discusses ways to create linkages between goals and investment decision making.

When managing the life cycle of existing assets, performance targets are commonly established as a way to manage service levels for the transportation network. How to determine the expected level of performance may vary depending on the type of asset being managed. Level of service targets that are part of performance framework typically are a mixture of both customer focused performance measures, and technical service measures that help those responsible for the asset assess what types of interventions might be required and when. Customer focused service measures are important to road users and other stakeholders that require mobility. Travel time reliability, safety, load capacity and clearances, and lane availability are all examples of service targets that are customer focused. Condition, strength, regulatory compliance and examples of technical service attributes are commonly of greater interest to asset stewards than asset users. Both types are service level targets that are important to evaluate the efficacy, effectiveness and efficiency of a transportation system.

For pavements and bridges, and other assets managed using a condition-based approach, asset condition is commonly used to establish expected technical levels of performance, but also is relevant to customers. For example, condition is employed as a proxy in this way for pavements because it is objectively measurable, deterioration has some predictability. It is a valuable service attribute because often, user experience is also directly connected to condition as well. Potholes, rutting and roughness all reduce quality of service from a pavement. Performance measures, such as those discussed in Chapter 6, are used to establish the desired long-term performance and to set short-term targets that can be used to track progress towards the long-term objectives. For other highway assets, including those managed using interval- or time-based maintenance approaches, performance may be linked to the expected service life, the ability of the asset to fulfill its intended function, and/or other operational factors. For these other highway assets, performance targets are often established as part of a Maintenance Quality Assurance (MQA) program in terms of desired maintenance levels of service (MLOS) and integrated with operational service targets that may also be customer focused.

Risk can also be used as a measure of performance. As described in chapter 2, risk considers both the potential impact and consequence of failure. This can be particularly useful when the potential consequences of failure impact other assets or facilities. An example of how Colorado uses risk to manage rockfalls is included in section 4.3 of this chapter. Additional details on how to track risk-based performance measures is included in Chapter 6.

Establishing a desired level of performance is typically a collaborative process that considers existing conditions, available funding, expected demands on the system, policy goals and guidance, and stakeholder priorities. The desired level of performance is typically established once baseline data is available, so performance trends can be evaluated. The desired level of performance may be adjusted over time to reflect changes in agency performance, changes in asset condition, capacity, safety, resiliency and other factors.

Three types of service expectations are often used in combination to manage asset performance:

• Performance target – the level of performance beyond which additional performance gains are not desired or worth the additional cost. When performance is measured based on condition, the desired performance may describe the desired state of good repair. There may be an expected specific time frame to achieve this desires performance target.
• Current Performance – an intermediate level of performance achieved by the organization and is usually reported relative to the desired target. Target setting is described in more detail in Chapter 5.
• Minimum acceptable performance – the lowest level of performance allowed for the asset or asset class to still function as designed.

Performance expectations may be set for the road network, a road corridor, for individual assets or for a group of assets. Commonly, performance expectations are set using a combination of asset class or subclass or sub network, such as:

• Key network corridors.
• Bridges on the National Highway System.
• Interstate pavements.
• Culverts larger than 10 feet in diameter.
• Traffic signals serving more than 10,000 vehicles per day.

The nature of performance expectations can be either strategic or tactical or operational. Strategic expectations support freight movement; for example, the long-term goal of providing unrestricted flow of legal loads is supported by a performance expectation of no load-posted or restricted bridges on interstate highways. This expectation cannot be accomplished without the tactical delivery of work to address factors contributing to the physical condition of bridges. Thus, an agency may include tactical expectations to perform maintenance and repair on structural members on a routine basis or as conditions warrant. These enhancements can be also integrated with renewal and other rehabilitation interventions to help improve both tactical performance metrics, as well as achieve higher level goals and objectives. Operational improvements such as more responsive snow clearance, and better signage are all integrated treatment options to achieve the strategic objective.

Life cycle management analysis, and the decisions it supports, require service levels, performance targets and other objectives to be able to determine the optimal choices for agencies to select during resource allocation. Over an asset life cycle, a range of interventions are possible, from reactive, routine and preventative maintenance, to large investment associated with renewal, replacement, or removal. Having targets helps select the right interventions and investment option while balancing risk, service and cost.

Connecting performance measures to higher level strategic goals also supports an agency’s ability to communicate how technical measures relate to system performance as experienced by highway users and other external stakeholders, thus tying asset management outcomes to system performance. Asset management measures are often very technical. Performance indicators like bridge ratings, pavement distress measurements, and risk ratings are not commonly understood by those outside transportation agencies. However, agencies can use these technical measures to support the performance indicators that are more commonly understood and prioritized by system users and external stakeholders. Communicating system performance and the status of the road network is discussed in Chapter 2, and is illustrated in several examples below. Customer service level targets are often established for this purpose, and give users an ability to understand the quality of service they should expect on the transportation system.

Adopting life cycle management can often achieve desired performance levels at lower life cycle costs than traditional strategies. Improved performance comes from analyzing the impact of various sequences of treatments on the future performance and costs of an asset class or subclass. By comparing the costs and benefits of long-term sequences of treatments, agencies can develop life-cycle strategies which provide the best practical long-term performance at lowest practical long-term costs. The implementation of life cycle strategies also enables an agency to better address its stewardship responsibilities and improve the alignment between agency investments and priorities.

By establishing sound long-term strategies, agencies can minimize the life cycle costs of preserving assets, while also managing asset performance to a defined target, the extent practicable with available resources. While strategies with a short-term outlook may provide better short-term performance, they can greatly increase the risk of higher future costs.

Life Cycle Strategies in Construction and Design Stages

Transportation infrastructure assets are expected to provide agencies with a desired level of performance over their design lives. To ensure the desired performance is achieved, decision-makers should consider factors that impact asset service life and future costs at the time of construction. This is commonly performed as part of the project development process to select a preferred design alternative. Factors to forecast should include design criteria, constraints, standards, and risks.

• Traffic
• Environmental and climatic conditions
• Material properties
• Design standards
• Operational constraints
• Construction practices
• Climate change
• Changing customer expectations
• Regional, state and national travel pattern changes
• Advancing technology

Because these factors contribute to asset performance, deterioration and the continued functionality of the asset, they must be considered when developing life cycle strategies in early and later stages of asset life. Life cycle strategies are based on an understanding of how these factors contribute to the rates of deterioration, how well the asset will accommodate future requirements and which treatments are effective in addressing deterioration or slowing the rate at which the asset deteriorates or underperforms.

Operation, Maintenance, and Rehabilitation Strategies

Treatment strategies consider how the asset, once constructed, will be managed to ensure it attains its design life, while maintaining the desired level of functionality. Special consideration should be given to long-life assets. There are three primary reasons short-term strategies are inefficient for long-life assets:

• As long-life assets age, deterioration accelerates, and there is greater risk of performance failing to meet current needs.
• As deterioration increases, the cost of treatments addressing deterioration tend to increase exponentially.
• Inexpensive treatments that restore condition but do not address the root cause of the deterioration will fail prematurely, leading to higher future costs.

These factors are reflected in Figure 4.4, which illustrates these concepts using a generic asset deterioration model. As shown in the figure, the average cost of treatment increases substantially as assets age. Additionally, the rate of deterioration tends to accelerate as assets age. Long-term strategies that use low-cost treatments early in an asset’s life cycle tend to improve asset condition very cost-effectively by deferring the need for most costly repairs.

Considering Transformational Changes in Life Cycle Management

Life cycle management requires an understanding of past performance to predict future performance and plan appropriate actions. However, as technology advances and society’s needs change, the inputs and objectives of life cycle management need to adapt. Technology can lead to new materials or techniques that allow agencies to get longer life from existing assets. However, technology can also lead to broader societal changes that may make the need for some assets obsolete. Similarly changes in standards and regulations, may make it necessary to replace or update some assets prior to the planned ends of their service lives. Asset managers should regularly review their assumptions about anticipated asset service lives, consider new treatment options, and adjust to technological and regulatory trends and adjust the life cycle approach accordingly. Much of the information to support this effort can be found in agency’s long-term planning documents, as discussed in Chapter 2.