WSDOT’s Pavement Program Provides Model for Improving the Reliability of its Bridge Cost Estimates

Appendix

Below, we directly compare details of the pavement and bridge estimating processes. The comparisons are in three categories in the tabs below.

Best Practices

Does WSDOT's estimating approach follow best practices?

WSDOT uses best practices to estimate current and long-term pavement needs, and partially does so for bridges. Below, we directly compare details of pavement and bridge estimating practices. The consultant’s detailed report addressing WSDOT’s use of best estimating practices is available for pavement and bridges. For this area, JLARC’s consultants addressed three practices, shown in the table below.

Does WSDOT: Pavement Bridges
  1. Project the deterioration rate?
 Yes Partial
  1. Know the effectiveness of its maintenance and preservation projects?
 Yes Partial
  1. Have the tools to analyze condition and long-term needs?
 Yes No

1. Does WSDOT project the deterioration rate?

Pavement Yes Bridges Partial
WSDOT can project pavement deterioration WSDOT has not developed deterioration models for all bridge elements

Best practice

State DOTs use performance models to predict pavement condition over time and determine the appropriate time for maintenance or preservation work. By projecting the rate that pavement conditions will change over time, a DOT can perform a life cycle cost analysis to compare the costs of different preservation alternatives.

WSDOT status

WSDOT develops site-specific performance models for three measures (pavement surface condition, profile condition, rutting condition) to characterize and predict performance. Every time WSDOT collects new condition data, staff enter it into the Washington State Pavement Management System (WSPMS). This updates performance models to help determine when different sections are due for treatment.

Best practice

State DOTs develop deterioration models for bridge elements to forecast the probability of different conditions and deterioration over time. These models allow states to:

  • Forecast the cost of needs caused by deterioration for a 10-30 year period;
  • Forecast network conditions at the end of the period, and
  • Perform life cycle cost analysis.

Needs assessments are based on an analysis of data at the bridge element level. An element is a bridge component, examples of which include bare concrete decks, uncoated metal bridge railings, or reinforced concrete columns.

WSDOT status

WSDOT maintains an inventory of over 160 elements, with each bridge having an average of about ten elements.  WSDOT has not developed deterioration models for all bridge elements.  It has analyzed steel coating systems, which includes estimates of paint and steel deterioration rates. These estimates, prepared from a combination of data analysis and judgment, are in the form of typical lifespans of coatings and of steel elements whose coatings have failed. WSDOT has also developed rules of thumb for the increase in deck deterioration that occurs during the period after an inspector discovers deck distress until a repair action can be completed.

WSDOT reports that its use of the steel coating and bridge deck analyses is ad hoc and not routine, primarily used at the project level (rather than for the inventory as a whole), and rarely documented.  A more comprehensive and systematic process is needed to support routine analyses of preservation and maintenance needs.
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2. Does WSDOT know the effectiveness of its maintenance and preservation projects?

Pavement Yes Bridges Partial
WSDOT can estimate the effectiveness of planned pavement work With a few exceptions, WSDOT has not measured the effectiveness of maintenance or preservation bridge work

Best practice

State DOTs forecast the effectiveness of a proposed program or set of preservation projects, and estimate its impact on the condition of the pavement network.

WSDOT status

After WSDOT completes preservation work, staff update the details in WSPMS. This ensures that the performance models and other data are specific to the type of work completed. This results in continuous re-calibration of the models, improving their accuracy in forecasting long-term needs.

Best practice

State DOTs use effectiveness measures to forecast the performance of the bridge inventory if it implements a proposed program of preservation projects. DOTs measure the condition of an element, such as metal bridge railings, before and after it completes maintenance or preservation work.

WSDOT status

Unlike its pavement preservation work, WSDOT has not measured the effectiveness of maintenance or preservation work for bridges in Washington, with few exceptions. WSDOT has:

  • Tracked before-and after data for paint and for certain types of deck overlays and patches.
  • Developed, but not yet tested, a method to evaluate the effectiveness of steel bridge washing.

In 2013, WSDOT provided the Legislature with a report that identified over $2.5 billion of preservation needs in excess of projected revenue for the ten-year period beginning with the 2013-15 biennium, $504 million of which was for bridge preservation. This report, known as the “Orange List,” forecast the condition of the bridge network at different funding levels (97 or 99 percent of bridges in fair or better condition). WSDOT based this condition forecast on professional judgment. The agency did not conduct a validated, quantitative analysis of deterioration or the effectiveness of treatments. It is not common practice to use judgment for this type of network-level forecast, and this approach is not supported by industry guidebooks.
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3. Does WSDOT have the tools to analyze condition and long-term needs?

Pavement Yes Bridges No
WSDOT has systems to analyze pavement data and estimate needed work WSDOT does not have a bridge management system to assist in identifying needs

Best practice

The American Association of State Highway Transportation Officials (AASHTO) outline the key capabilities of pavement management systems. These include:

  • Enhanced planning ability at all levels, including network and project;
  • Decision-making based on observed and forecasted conditions rather than opinions; and
  • The ability to generate alternate scenarios for long-term pavement conditions based on different budget scenarios or management approaches.

WSDOT status

Consultants found that WSDOT’s pavement management system meets industry standards. They note that WSPMS generates accurate and reliable estimates at the planning and project levels through an objective, data-driven process that includes the opinions of WSDOT regional and State Material Laboratory staff.

Best practice

State DOTs use current inspection data, forecasting models for future deterioration and costs and life cycle cost analysis to estimate bridge needs. Most state DOTs use a bridge management system for this purpose. This analysis is often supplemented with agencies’ own judgment and knowledge of program plans, environmental issues, and other site-specific information affecting the feasibility of projects.

WSDOT status

Unlike most states, WSDOT does not have a bridge management system to assist in identifying needs. WSDOT’s approach, which relies on current condition data and professional judgment, is labor intensive, cannot be easily replicated, and is not able to produce alternative scenarios that would allow policy makers to optimize investments in bridges.  WSDOT uses its pavement management system to perform such work for its pavement estimates.

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Life Cycle Costs

Does WSDOT's estimating approach minimize life cycle costs?

WSDOT uses best practices to minimize pavement life cycle costs, but does not do so for bridges. Below, we directly compare the agency’s use of life cycle cost analysis for pavement and bridges. The consultant’s detailed report addressing WSDOT’s approach to minimizing life cycle costs is available for pavement and bridges. For this area, JLARC’s consultants addressed four practices, shown in the table below.

Does WSDOT: Pavement Bridges
  1. Use Life Cycle Cost Analysis (LCCA) at the project level?
 Yes Partial
  1. Use LCCA to manage the network?
 Partial No
  1. Consider the tradeoffs between earlier, routine maintenance and preservation work later in life?
 No Partial
  1. Estimate its backlog and estimate different fiscal scenarios?
 Yes Partial

1. Does WSDOT use LCCA at the project level?

Pavement Yes Bridges Partial
WSDOT has determined the most cost effective time and type of work to maximize pavement life WSDOT uses maintenance and preservation strategies that are not specific to Washington

Best practice

State DOTs use software to conduct a detailed life cycle cost analysis to determine the most cost-effective pavement design for new pavement, reconstruction, and major rehabilitation projects.

WSDOT status

WSDOT routinely uses Federal Highway Administration software to perform project-level life cycle cost analyses on all new design, reconstruction, and major preservation projects to determine the most cost-effective project. WSDOT’s approach to planning pavement preservation treatments builds lowest life cycle cost analysis into the pavement management process. From in-house studies and its application of the pavement management program, WSDOT has determined the optimal time to apply pavement preservation treatments. If the work is done after that time, the pavement will require more expensive work. If the work is done before then, work may not yet be necessary, resulting in higher long-term costs.

Best practice

State DOTs keep up-to-date with industry research, methods, and products to find preservation and maintenance strategies to minimize the life cycle costs of individual structures. Most DOTs also conduct their own research to determine which treatments work best under local conditions. Bridge inspectors use this information to recommend treatments for specific structures based on the conditions they see in the field. The same decision rules are used in life cycle cost analysis to create life cycle activity profiles, where DOTs use the forecasted future condition of a bridge to identify long-term projects and their costs.

WSDOT status

Unlike the pavement program, which has conducted in-house studies, WSDOT’s bridge analyses rely on industry publications and best practices, using preservation activities shown by other DOTs to minimize life cycle costs. Examples include its painting and bridge deck programs. WSDOT has not documented its analysis to show whether the lifespans of paint and steel and bridge decks presented in industry publications agree with lifespans derived from historical WSDOT inspection data. There is no process to extend a similar analysis over all the diverse bridge elements in the Washington inventory. Because WSDOT’s current approach is very labor-intensive, the department lacks a practical way to analyze alternative program scenarios or to model the effect of uncertainty.

return to Life Cycle Costs questions

2. Does WSDOT Use LCCA to manage the network?

Pavement Partial Bridges No
WSDOT uses life cycle cost analysis to determine its long term funding needs, but may be able to further extend pavement life WSDOT does not have models or software to help estimate long-term maintenance and preservation costs

Best practice

When an agency considers different maintenance and preservation strategies, including preventive maintenance, a life cycle cost analysis approach will help determine the most cost effective strategy over the long term.

Exhibit 4 illustrates the investment costs associated with performing preservation work earlier while the pavement is still in good condition as compared to completing work when conditions have deteriorated—treatment costs increase as the pavement ages and its condition deteriorates.

Exhibit 4 - Work completed earlier in asset life can avoid much more expensive work later
Maintenance and preservation work, performed when Pavement Condition Index (PCI) is above 60, cost less per square foot than reconstruction work that is required at lower PCI values
Source: JLARC staff adaptation of chart by Los Angeles County Department of Public Works.

WSDOT status

WSDOT reports that its primary objective for managing pavement at the network level is to manage to the lowest life cycle cost.  WSDOT began using LCCA in the early 1990s to estimate the total pavement network maintenance and preservation needs in a cost-effective manner.  JLARC’s consultants noted that “WSDOT’s methods stood out from other states’ practices” because it determines funding needs using pavement preservation strategies that produce the lowest life cycle cost and satisfy the performance criteria. 

While JLARC’s consultants note that WSDOT has LCCA built into its analysis for future needs, they also note that the agency could benefit by considering earlier, additional pavement strategies. Doing so may defer costlier preservation work and further reduce life cycle costs.  WSDOT’s current approach is to apply preservation work later in the life of the pavement.   WSDOT would need to analyze these treatments in Washington to determine their effectiveness in local conditions. JLARC’s consultants offer a suggestion in the following section to improve this aspect of pavement management.

Best practice

Treatments that are appropriate and effective for a specific condition found on a given bridge are not necessarily treatments an agency can afford to perform statewide. Similarly, strategies that minimize project life cycle costs are not necessarily the same strategies that minimize network life cycle costs.

WSDOT status

For pavement, WSDOT uses Washington State Pavement Management System (WSPMS) to assist with estimating long-term pavement maintenance and preservation costs. For bridge estimates however, it does not have a similar model or software to compute life cycle costs, and lacks the ability to generate alternatives and optimize them. As a result, WSDOT cannot determine whether bridge life cycle costs are minimized at the network level.
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3. Does WSDOT consider the tradeoffs between earlier, routine maintenance and preservation work later in life?

Pavement No Bridges Partial
WSDOT has not integrated maintenance and preservation activities for its analyses, but WSDOT is working to do so WSDOT completes maintenance work to reduce future costs, but has not determined the optimal allocation between maintenance and preservation

Best practice

Few states include maintenance costs in pavement life cycle cost analysis. These costs are relatively low (see Exhibit 4) and are often not tracked in a manner that allows for their incorporation in network level life cycle cost analysis.  However, incorporating maintenance and preservation is a best practice. Applying earlier, preventative maintenance treatments may extend the service life of pavement, as compared with doing preservation work later in pavement’s life.

WSDOT status

WSDOT has not incorporated maintenance costs into its life cycle cost analysis. It is working to do so, and completed a pilot project in its Olympic Region to include maintenance costs in LCCA. WSDOT is implementing a new Highway Activity Tracking System, which may allow it to include routine maintenance costs in its analyses.

Consultant's Observation

WSDOT may be able to lower pavement life cycle costs by considering earlier treatment timing for asphalt and chip seal pavements and by incorporating maintenance costs into the analysis.

Best practice

Life cycle cost analysis is most useful for extending bridge service life and postponing replacement. State DOTs can also use it to design maintenance policies and analyze the tradeoff between preservation and maintenance:

  • A disciplined maintenance policy, such as bridge washing, can slow the deterioration rate and promote a less frequent need for preservation work.
  • Well-timed preservation work can improve the effectiveness of a maintenance program and extend the life of a structure.

When integrated, these programs can minimize life cycle costs for a given level of investment.

WSDOT status

WSDOT completes maintenance work with the intent of reducing future costs, such as bridge washing, bridge deck maintenance, and annual expansion joint cleaning. However, without a model to compute life cycle costs, WSDOT does not have a means to quantify the optimal allocation of funding between maintenance (operations funding) and preservation (capital funding).  WSDOT may be able to reduce long-term costs by placing more emphasis on one category or the other, but the agency lacks quantitative evidence to support such a decision.
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4. Does WSDOT estimate its backlog and estimate different fiscal scenarios?

Pavement Yes Bridges Partial
WSDOT can consider investment alternatives for the pavement network. WSDOT cannot link different investment scenarios to the expected condition of the network

Best practice

For a DOT to manage a pavement network at the lowest possible life cycle cost under financial and other constraints, an agency must use prediction models and prioritization tools to determine which projects will produce an acceptable condition that can be financially sustained. The agency should have tools to analyze a variety of scenarios that tie performance outcomes with fiscal alternatives.

Optimal condition is the set of network-wide conditions that are acceptable and that the agency can sustain over the long term at a constant funding level, at the lowest life cycle cost. Backlog is the extra cost that an agency would incur in order to bring the inventory to its long-term optimal condition. Determining this backlog requires models of deterioration, cost, and effectiveness.

WSDOT status

WSDOT has a process to consider network-level investment alternatives, including: optimizing the allocation of resources; estimating the cost of attaining a given set of performance targets; and estimating the performance and backlog which might result from a given investment level.

Best practice

For a DOT to manage a bridge network at the lowest life cycle cost under financial and other constraints, an agency must use prediction models and prioritization tools to determine which projects will produce an acceptable condition that can be financially sustained. The agency should have tools to analyze a variety of scenarios that tie performance outcomes with fiscal alternatives.

Optimal condition is the set of network-wide conditions that are acceptable and that the agency can sustain over the long term at a constant funding level, at the lowest life cycle cost. Backlog is the extra cost that an agency would incur in order to bring the inventory to its long-term optimal condition. Determining this backlog requires models of deterioration, cost, and effectiveness.

WSDOT status

WSDOT does not have the ability to analyze alternative scenarios for bridge preservation and maintenance that tie funding levels to performance outcomes. This limits WSDOT’s ability to manage the bridge network at the lowest possible life cycle cost given financial and other constraints.

WSDOT has estimated unfunded bridge preservation and maintenance work needs that it refers to as a backlog. Its estimates are based on treatments that it believes are best practices.  The treatments are a mixture of needs that it can safely delay and others that it cannot delay without increasing future costs. WSDOT did not base its backlog estimates on a life cycle cost analysis of optimal conditions, and cannot substantiate that proposed treatments will minimize system-wide costs.
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Risk

Does WSDOT's estimating approach address risk?

WSDOT uses best practices to incorporate risk in the estimating process for pavement, and partially does so for bridges. Below, we directly compare details of incorporating risk into estimates for pavement and bridges. The consultant’s detailed report addressing WSDOT’s approach to estimating risk is available for pavement and bridges. For this area, JLARC’s consultants addressed three practices, shown in the table below.

Does WSDOT: Pavement Bridges
  1. Quantify systemic risks (such as changes in material costs) and site-specific risks (such as floods or severe storms)?
 Yes Partial
  1. Analyze different investment alternatives based on various fiscal scenarios?
 Yes No
  1. Consider risk in prioritizing projects and long-term work?
 Yes No

1. Does WSDOT quantify systemic risks (such as changes in material costs) and site-specific risks (such as floods or severe storms)?

Pavement Yes Bridges Partial
WSDOT accounts for risk in its pavement cost estimates. WSDOT accounts for systemic risk in its estimates, but does not consider all of the site-specific elements

Best practice

JLARC’s consultants identified two varieties of risk:

  • Systemic risks:  examples include market fluctuations, budget restrictions, and insufficient or inaccurate data; and
  • Site-specific risks:  examples include sudden condition-related failure, natural hazards and climate change impacts, and man-made hazards.

For pavement, best practice is to minimize systemic risks and manage site-specific risks on a case by case basis.

WSDOT Systemic Risk Status

WSDOT routinely incorporates systemic risks into its long-term estimates of pavement needs. 

  • Risks to expenditures:  WSDOT tracks fluctuations in material costs, and has developed spreadsheet tools to assist in price adjustment calculations associated with pavement materials.
  • Risks to revenues: WSDOT developed vehicle miles travelled (VMT) projection models, which help the agency understand the impact of changes in VMT to its revenue projections. The forecasted trends suggest that that vehicle miles traveled has flattened in recent years, and that slower growth is projected for future VMT.

WSDOT Site-specific Risk status

WSDOT does not quantify site-specific risk in its long-term estimates, which is consistent with industry standards.  Site-specific risks are not expected to occur uniformly over the entire network.  WSDOT handles these risks on a case-by-case basis. Since instantaneous failure does not usually occur on pavements, these risks can be prioritized and managed on an as-needed basis.  The consultants do not recommend that WSDOT try to incorporate such risks in its long-term pavement needs estimates.

Best practice

JLARC’s consultants identified two varieties of risk

  • Systemic risks:  examples include market fluctuations, budget restrictions, and insufficient or inaccurate data; and
  • Site-specific risks:  examples include sudden condition-related failure, natural hazards and climate change impacts, and man-made hazards.

For bridge management, best practice is to address both types of risk.

WSDOT Systemic Risk Status

WSDOT routinely tracks its costs and can quantify past variances. It has the necessary information to develop estimates of long-term inflation and can analyze alternative scenarios.

  • Risks to expenditures:  WSDOT tracks fluctuations in material costs, such as steel reinforcing bar.
  • Risks to revenues: WSDOT developed vehicle miles travelled (VMT) projection models, which help the agency understand the impact of changes in VMT to its revenue projections. The forecasted trends suggest that that vehicle miles traveled has flattened in recent years, and that slower growth is projected for future VMT. 

WSDOT Site-specific Risk status

WSDOT quantifies two of three types of site specific failures identified by JLARC’s consultants. WSDOT quantifies and accounts for condition caused failures in its long-term estimates by providing an allowance for functionally obsolete bridges, and accounts for the risk of natural hazards such as earthquake, scour, and fire. WSDOT does not consider risk mitigation for man-made hazards, such as collisions, in its long-term estimates. It does not have the ability to estimate network level bridge “strengthening” or “raising” needs. Considering risk mitigation for man-made hazards is not a common practice among state DOTs, but is a best practice.
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2. Does WSDOT analyze different investment alternatives based on various fiscal scenarios?

Pavement Yes Bridges No
WSDOT can analyze the expected results of different investment levels WSDOT is not required to develop performance constrained scenarios and has not done so

Best practice

For long-term maintenance and preservation needs estimates to incorporate the impacts of market fluctuations, a DOT should be capable of analyzing “what-if” scenarios like:

  • What if funding levels are reduced by 50 percent or 75 percent?
  • What if interstate pavements are prioritized over principal arterials?
  • What if chip seal needs are funded before addressing other needs?

WSDOT status

The Washington State Pavement Management System helps WSDOT answer “what-if” questions, such as those posed above. WSDOT routinely tracks the investments made in pavement preservation efforts and the impact on overall network conditions.

Best practice

For long-term maintenance and preservation needs estimates to incorporate the impacts of market fluctuations, a DOT should be capable of analyzing “what-if” scenarios like:

  • What if funding levels are reduced by 50 percent or 75 percent?
  • What if bridges on critical freight routes are prioritized over other bridges?

WSDOT status

WSDOT states that it would be technically feasible to develop consistent scenarios of performance, cost, and funding if given the necessary data and tools. However, WSDOT reports that developing a performance-constrained bridge preservation and maintenance needs estimate has not been an institutional requirement expected of the Department, and such an estimate has not been completed. WSDOT has completed such work for its pavement program.
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3. Does WSDOT consider risk in prioritizing projects and long-term work?

Pavement Yes Bridges No
WSDOT uses risk to inform project prioritization Risk is not integrated into priority setting

Best practice

Very few highway agencies consider risk through a formalized framework within their pavement management system. Poor pavement conditions pose higher risks, both to users and the agency. However, it is not the only factor influencing the level of risk. Other factors, such as traffic levels, truck traffic, and the criticality of route, contribute to the overall level of risk.

WSDOT status

WSDOT is one of the few DOTs that formally considers risk during the project prioritization process.  Risk is considered as one of the performance measures within its pavement management system. WSDOT recently developed a risk register to account for the additional risk associated with deteriorated pavement.  This register considers the likelihood and consequences of a roadway failing so that WSDOT can direct resources to address potential high risks.

Best practice

A few DOTs have developed risk-based priority setting processes that incorporate all of the significant condition-based, natural, and man-made hazards in their state. Prioritizing these measures affects the number of bridges that will be allowed to remain in poor or vulnerable condition, rather than being mitigated or replaced, over the 10-year period. Without an objective way of prioritizing, the allocation of resources among risk categories is arbitrary or subjective.

WSDOT status

WSDOT does not have a method to consider risk in priority setting for bridges. JLARC’s consultants suggest that WSDOT would benefit from an objective process to determine how much each risk category needs over 10 years, consistent with other Department priorities and within fiscal constraints. This is not yet common practice among state DOTs, but it is best practice.
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