Pavement Preservation Compendium II
The Seven Stallers
by Katie Zimmerman, P.E. and David Peshkin, P.E.
Highway agencies are increasingly turning to pavement preventive maintenance programs. Preventive maintenance slows the rate of pavement deterioration, essentially delaying the need for pavement rehabilitation by several years (see Fig. 1). The delay in rehabilitation needs, combined with the fairly low cost of preventive maintenance treatments, can result in dramatic cost savings for pavement preservation. Other benefits of a preventive maintenance program include:
- Higher customer satisfaction with the road network;
- The ability to make better, more informed decisions on an objective basis;
- The more appropriate use of maintenance techniques;
- Improved pavement conditions over time;
- Increased safety; and
- Reduced overall costs for maintaining the road network.
Figure 1. Use of preventive maintenance treatments to defer the need for rehabilitation.
Although there are significant reported benefits from preventive maintenance, starting such a program is not a trivial undertaking; implementation often requires a fundamental shift in the philosophy of the transportation agency. To a large degree, the challenges agencies face when initiating these changes are caused by misconceptions about pavement preventive maintenance. This article addresses seven of the most deadly misconceptions about pavement preventive maintenance. These misconceptions are deadly because any one of them is enough to stop a program in its tracks. Therefore, suggestions for addressing each misconception also are provided, based on the authors' experiences working with agencies that have been using preventive maintenance concepts for years as well as agencies that are just beginning to implement these programs.
The seven bullets
We can't start a preventive maintenance program until our backlog is gone.
Any agency that has inadequate funding to address its pavement rehabilitation and reconstruction needs is faced with the challenge of a continuously growing backlog of identified, but unfunded, projects. As long as there are roads that need rehabilitation, agencies find it difficult to move away from an improvement program that is primarily oriented towards addressing the worst roads first. This is especially true when the agency is considering dedicating a portion of its improvement funds to a program that includes the application of preventive maintenance treatments to roads in good condition.
An effective way to counter this argument is to use a pavement management system to demonstrate the effect of each improvement program (one that addresses the worst roads first and the other that includes rehabilitation and preventive maintenance treatments) on overall network conditions. Agencies that have used pavement management to demonstrate the importance of starting a preventive maintenance program to help reduce the size of an agency's pavement backlog have found that the results take time to be realized. But, as shown in Fig. 2, eventually a preventive maintenance program results in dramatically different network conditions because of the reduced rate in which the backlog grows with preventive maintenance. Since preventive maintenance treatments are applied to roads in good condition, they remain in good condition for a longer period of time; thereby reducing the rate at which the backlog grows while a portion of the program is targeted to addressing those roads already in a backlogged condition.
Figure 2. Impact of two preservation strategies on overall network conditions.
We're already using preventive maintenance treatments.
Many agencies report they are already using the types of treatments normally included in a preventive maintenance program, such as those shown below:
- Crack filling or crack sealing;
- Joint resealing;
- Surface treatments such as fog seals, sand seals and chip seals;
- Slurry seals and microsurfacing;
- Thin hot-mix asphalt (HMA) overlays;
- Diamond grinding;
- Joint spall repair;
- Load transfer restoration; and
- Maintenance of drainage facilities.
The key to the use of these treatments as part of a preventive maintenance program is the early application of the treatment before major structural deterioration has taken place. In most cases, this means applying these treatments while the roads are in fairly good condition, instead of applying the treatment as a corrective treatment until more substantial treatments can be applied.
For most agencies, the early application of pavement preventive maintenance treatments represents a marked difference in the way road networks are managed. Traditionally, most agencies have followed programs in which no treatments were applied until rehabilitation or reconstruction activities were required (after pavement conditions fell below an acceptable level). Some routine maintenance may have been performed, but the funding for the maintenance activities was usually unreliable and the highest priority for funding came from stopgap, or safety, maintenance needs.
Agencies with preventive maintenance programs in place are including preventive maintenance treatments as part of a planned strategy to slow the rate of pavement deterioration, thereby deferring the need for rehabilitation. It is this early, planned application of the preventive maintenance treatments that marks one of the primary differences from the way these treatments have been used in the past.
It can't be cost-effective if you're applying treatments more frequently.
A preventive maintenance program requires the early application of treatments, while roads are still in relatively good condition. Admittedly, the life of a preventive maintenance treatment is not as long as the expected life of a rehabilitation treatment, so can it still be cost-effective to apply more frequent treatments without causing increased disruptions to the traveling public? The answer is yes.
A life-cycle cost analysis is one way of comparing the costs associated with maintaining a pavement facility over an analysis period that includes at least one rehabilitation cycle. An example of this application is provided.
In the first application, represented by strategy A, an initial treatment is constructed at a cost of $400,000. A minor rehabilitation treatment is applied in years 8 and 16 at a cost of $80,000 for each application. Routine maintenance costs associated with this strategy are $500 per year and the salvage value associated with the last application of the year 16 treatment is $40,000 (since half of the life of the treatment is used at the end of the analysis period, half of the cost of the strategy is considered the salvage value). The expenditure stream diagram associated with this strategy is shown in Fig. 3.
Figure 3. Expenditure stream diagram for Strategy A.
The second strategy, represented by strategy B, is presented in Fig. 4. This strategy is comprised of the same initial treatment, with a $12,000 preventive maintenance treatment applied in years 4, 8, 12 and 16. Annual maintenance costs associated with this strategy are $800/year and there is no salvage value since the life of the last treatment is used up at the end of the analysis period.
Figure 4. Expenditure stream diagram for Strategy B.
The present worth values associated with each strategy are presented below. Both examples are based on a 20-year analysis period and a discount rate of 4%. The example demonstrates that strategy B, which included more frequent applications of a lower cost treatment, resulted in a lower life-cycle cost, and that preventive maintenance treatments can reduce the cost of preserving the pavement network. The more frequent application of preventive maintenance treatments typically doesn't interfere with normal traffic operations because many of the treatments can be applied at night, or during a relatively short closure.
Decision-makers will never support this type of program.
Once an agency can demonstrate the cost effectiveness of preventive maintenance to decision-makers, it is easier to convince these individuals of the benefits associated with such a program. Consider the following when promoting preventive maintenance program to management:
- Don't oversell the program: Several agencies have determined that preventive maintenance programs greatly reduce their overall cost of maintaining a pavement network. However, when reporting the cost savings to decision-makers, these agencies have been conservative in reporting the benefits that the agency will realize. As a result, the agencies are much more confident of their ability to meet their targets.
- Remember that it takes time for the benefits to be realized: Although some benefits associated with the use of a preventive maintenance program may be immediate, the improvement in network conditions and overall reduction in life-cycle costs may take time to be realized by the agency. For example, it took the Georgia DOT about 15 years to achieve a "steady state" condition for their pavement network. It is important that decision-makers understand this so that support for a program is not suspended before the results are realized.
- Communicate the preventive maintenance concept in terms that decision-makers can understand: Most of us are familiar with the use of preventive maintenance concepts in their every day life, from routine visits to the dentist to maintenance schedules for cars and other vehicles. The application of these concepts to pavements is very similar. We don't postpone maintenance on our cars until the engine seizes; why would we apply this approach to pavement preservation? Communicating the message in a way that decision-makers can understand helps to secure their support.
- Set goals for the program: An effective preventive maintenance program should be established with clearly defined, measurable goals that can be achieved within a stated timeframe. Over time, progress towards the goal should be monitored and reported to the decision-makers to continually build support for the program. An example of an effective goal is to have at least 70% of the pavement network in good condition within a five-year period. A pavement management system can be used to help establish a reasonable goal for a preventive maintenance program.
Preventive maintenance is solely the responsibility of the maintenance department.
Although in many agencies placing preventive maintenance treatments is primarily the responsibility of maintenance crews, a preventive maintenance program must be supported by individuals at all levels of the organization to be successful. At the policy level, dedicated funding will support the preventive maintenance program. At this level, managers can promote the preventive maintenance philosophy within the organization, support the program among political factions and provide the resources needed to embrace the philosophy within the organization.
|Present Worth of Strategy A|
|PW (routine maintenance)||=$ 6,567|
|PW (treatment 1)||=$ 58,455|
|PW (treatment 2)||=$ 42,713|
|PW (salvage value)||=$ -18,255|
|Present Worth of Strategy B|
|PW (routine maintenance)||=$ 10,507|
|PW (all four treatments)||=$ 32,928|
|PW (salvage value)||=$ 00|
The preventive maintenance program also must be supported by design, pavement management, research, planning and programming, and construction. Designers should consider the effect of pavement designs on maintenance needs and pavement performance. Pavement management should incorporate preventive maintenance treatments into the analysis of pavement maintenance and rehabilitation needs for planning and programming activities. Research can provide information on the optimal timing of preventive maintenance treatments based on agency performance studies, and construction can help ensure that the quality of preventive maintenance treatments is incorporated into the construction activities. Finally, individuals in planning and programming functions can help ensure that preventive maintenance treatments are applied on a timely basis, before too much pavement deterioration has taken place. In short, preventive maintenance is not the sole responsibility of maintenance, but represents a paradigm shift within the agency that must be supported by all.
The public will never understand why we're working on good roads.
Where there is a general mistrust of government and public employees, having treatments applied to roads in good condition will only further fuel that feeling. This is especially true if there are still plenty of roads in poor condition that are not being treated.
Since the public also wants government to be accountable, perhaps the best way to fend off the anticipated negative public response is to promote preventive maintenance among civic groups, special interest groups and the general public through presentations at meetings, press releases and material placed on the Internet. This is essentially a public relations campaign. The materials that are used should illustrate the cost-effectiveness of a preventive maintenance strategy and the resulting benefits in terms of network conditions, improved safety and better levels of service. As with the decision-makers, explaining pavement preventive maintenance in terms that the public understands, such as house or car maintenance, is an effective means of conveying the agency's philosophy to the community.
Our agency can't afford this type of a program.
In reality, your agency can't afford NOT to consider a pavement preventive maintenance program as a strategy for preserving its investment in its transportation assets. Not only have preventive maintenance programs been shown to reduce the overall cost of preserving the pavement network, but additional benefits have been realized in terms of improved safety, better network conditions and higher customer satisfaction. Many agencies have funded their preventive maintenance programs with new funds obtained through increased taxes or the reallocation of funds from other sources. However, several agencies have successfully implemented preventive maintenance programs without levying additional taxes. Granted, the benefits may come a little slower without additional funds, but any level of commitment to a preventive maintenance program will eventually result in benefits to both the agency and the traveling public.
The preservation of a pavement network is a challenge to both public and private transportation agencies. Pavement preservation strategies, including the use of pavement preventive maintenance treatments, have emerged in the last few years as a cost-effective means of maintaining the functional condition of a road network.
To be effective, a pavement preservation program requires a shift in the operations of most transportation agencies. Instead of using maintenance funds to address only stopgap measures, funds are allocated to the construction of preventive maintenance treatments while pavement is still in relatively good condition. To effectively implement this type of change within a transportation agency, the benefits of such a program must be demonstrated using available tools, such as a pavement management system.
Resources are available to assist agencies in implementing a preventive maintenance program. For example, the Federal Highway Administration's (FHWA) National Highway Institute (NHI) offers a series of training courses on pavement preservation activities such as preventive maintenance. Courses currently available or under development include topics on the preventive maintenance concept, selecting projects that are good candidates for preventive maintenance, the construction of quality preventive maintenance treatments and the integration of preventive maintenance treatments into a pavement management system. Information on NHI training courses is available at the NHI web site.
Other organizations actively promoting the use of preventive maintenance treatments are supported by a combination of governmental, private and academic agencies. The Foundation for Pavement Preservation (FP2) is one such example. Through its website and its support for pavement preservation forums and conference sessions, FP2 has been an early leader in providing resources to support agency practices in this area. In conjunction with the FHWA, the Foundation has recently supported the development of the National Center for Pavement Preservation at Michigan State University. The National Center for Pavement Preservation is expected to be involved in furthering research and training efforts in the area of pavement preservation. More information on the Center is available through the National Center for Pavement Preservation web site.
Reprinted from Roads & Bridges, December 2003.