Dennis Polhill

Prepared for Presentation to
29th Annual Highway Engineering Conference,
Las Cruces, New Mexico, March 24 and 25, 1983

By Ralph Haas, PhD., P.Eng.,
Chief Executive Officer,
The PMS Group, Paris, Ontario, Denver and Calgary,
and, Professor of Civil Engineering, University of Waterloo

 

and
Dennis Polhill, NIS, MPWA, P.E.,
President, PMS (Colorado), Inc.,
Denver, Colorado

SUMMARY

We have billions of dollars invested in our roads and streets. This investment has to be preserved through timely and cost-effective maintenance and rehabilitation. However, we are faced with fiscal restraint. Good pavement management provides a means for obtaining maximum value for the limited funds available.

This paper describes the major elements of pavement management for both the network and project levels. The network level starts with good inventory data and should produce priority programs of capital and maintenance work. The project level is concerned with detailed design and construction.

Three basic classes of pavement management users: elected representatives, administrators and technical people are considered in the paper, as well as their particular requirements.

Several other issues or questions are addressed, including the relationship between pavement management and road needs studies, the private sector role in pavement management, the effect of size of agency, the benefits to be expected from pavement management and the costs.

The paper suggests that the essential ingredient for successful pavement management implementation is a staged approach, including a pre-implementation planning stage and useable “products” available from each stage. These should be modular and stand-alone.

The role of consultants is explored, including advantages and disadvantages. An evaluation procedure is provided, and some of the problems faced by consultants are outllined.

Finally, some suggestions are made as to how to get started in pavement management.

INTRODUCTION

Conditions of restraint spur the need for good management. Limited available dollars have to be spent wisely. Nowhere is this more important than in transportation. The investment is large and it must be preserved.

The paved road network represents a particularly large portion of the total transport investment. In New Mexico alone this portion amounts to several billion dollars.

To preserve this investment, cities, counties and the State require at least several hundred million dollars each year for rehabilitation and maintenance. That is aside from the sums required to catch up on a backlog of needs.

Pavement management can certainly help in effectively spending even the limited available dollars for rehabilitation and maintenance. The question for most people is what does this term pavement management mean, how can it help us and what does it cost?

It is the purpose of this paper to answer that question, to explore the potential role of consultants, and to offer some suggestions to those who want to get started in pavement management.

PAVEMENT MANAGEMENT

Basic Objective and The Major Questions

The objective of pavement management has already been implied: preserve the investment and make the best possible use of limited available dollars. Nobody would disagree with that, but they would want to know how the objective is actually accomplished; in other words:

1. What are the key elements of pavement management?
2. What sort of answers should it provide for the elected, administrative and technical levels of a local authority or the State?
3. What is the role of the private sector: contractors, suppliers, consultants?
4. What are the benefits to be expected, and the costs?
5. How do we get started, what’s the first step?

Key Elements of Pavement Management

Pavement management is a process for carrying out in a co-ordinated, systematic way a11 those activities that go into providing pavements (1 to 3). It can be viewed in terms of two basic working levels: (a) network and (b) project. Figure 1 lists the major activities occurring at both levels.

Network level management has as its primary purpose the develop-ment of a priority program and schedule of work, within overall budget constraints. Project level work thus comes “on stream” at the

appropriate time in the schedule. Since the network level of management is usually based on more approximate data and analyses, considerable “fine tuning” may be required when it comes to detailed project design and construction or section maintenance.

The ‘Users’ of Pavement Management and Their Requirements

The actual “users” of pavement management, whether the network or project levels are concerned, whether the State or a local authority is involved, can conveniently be classified as follows:

1. Elected representatives
2. Administrators
3. Technical people.

Each type of user has certain requirements from a pavement management system and these are summarized in Figure 2. Obviously there is some overlap but what Figure 2 shows is that pavement management is not just done by administrators. In order to function successfully it has [o rely on people ranging from the technician who plans and carries out a testing program to the elected representative who approves or modifies a budget request.

Relationship Between Pavement Management and Road Needs Studies

The purpose of a road needs study is to arrive at inventory or appraisal of the total road system and provide a basis for planning and development policy. It should also provide a comprehensive assessment of road and bridge needs, the priority rankings attached to them and the costs of meeting those needs in various time periods; i.e., now, L to 5 years and 6 to 10 years.

The question is how does pavement management fit m with the Road Needs Studies? First, it should be pointed out that the studies are not a management tool, per se. They provide an inventory, a first cut estimate of needs, and, perhaps most important, the basis for financial planning. The next step is to actually spend those dollars in the most cost-effective way, starting with a determination of “real needs”.

In other words, for the pavement portion, a pavement management system can take over where the road needs study leaves off (i.e., it can “fine tune” the needs study results. As well, the objectively based data collected for pavement management purposes at the network level (i. , roughness, surface condition, geometrics, deflection, etc.) can be used directly to update the road needs studies. Thus, a pavement management system can and should be entirely complementary to the road needs study, and to higher level highway and transportation management in general.

STAGED IMPLEMENTATION

There are several essential ingredients to having a successful pavement management system (PMS) and one of the most important is staging. This step by step approach, if it is done as part of an overall, long term plan, has the following advantages: (a) it provides a modular system with useable, stand-alone products at the end of each stage, (b) the PMS can start to be used fairly quickly, (c) it can be accommodated to resources, (d) it recognizes the “learning curve” and time required for acceptance by an organization.

The major considerations in staged implementation are described in the following paragraphs.

Stages and Produces

Figure 3 shows the major stages which can be used in implementing a PMS. Also listed are the key products.

A pre-implementation planning stage is shown in Figure 3 as the beginning of the process. This can be most valuable in facilitating the actual implementation and is further discussed in the next section.

The first three stages of Figure 3 occur at the network level while the next three occur mainly at the project level

A description of the six stages of Figure 3 , and actual examples of the products,is beyond the scope of this paper. However, there are some good references which illustrate these in some detail. For example, Idaho (4) and Alberta (5) have very well developed Stage 1 systems. These include performance prediction models so that future needs can be estimated. Both agencies are in the process of developing and implementing Stage 2. Alberta has plans [o develop the remaining four stages listed in Figure 3, while Idaho already has implemented Stage 4 as part of their pavement management system (4).

There are good examples of working priority programming systems for rehabilitation, Stage 2, in Ref. (6, 7) while Ref. (8) contains an example of a Stage 3 maintenance programming system.

There are many examples of good structural design and life cycle costing systems for new pavements (3), Stage 5, which have already been developed. However, there are far less examples of how they have been integrated or modified to fit into an overall PMS.

The operational deficiency and improvement analysis system, Stage 6, which relates to safety, capacity, geometrics, etc. is usually treated at the broader highway level. Explicit integration with a PMS represents a major challenge which to date has not apparently been accomplished by any agencies.

There is some flexibility in carrying out the stages of Figure 3, with the exception of Stage 1 which is the foundation for all other stages. Stage ? would normally be nest; after that, the sequence can vary, but it is essential that it be properly planned.

Pre-Implementation Planning

Pre-implementation planning (Stage “0″ of Figure 3) can result in a much easier, efficient implementation, and enhance the acceptability of the PMS. Its purpose is to let the client knew exactly what their

PMS will do, how it will operate, what answers it will provide, what resources will be required, etc. Then, when they agree, or after any desired modifications are made, the actual implementation can proceed. The pre-implementation procedure has been very successfully used for both State and city level PMS projects by the authors of this paper and their colleagues.

It essentially consists of the following:

1. Detailed planning (identification and articulation of the – client’s goals and objectives, finalization of the work plan, detailed project schedule),
2. Evaluation of the client’s existing conditions, resources . and procedures (characteristics of the road network and existing data, organizational structure, physical resources including equipment, human resources, facilities including computer hardware and software,operating procedures, documentation system, maintenance facilities, equipment and operations, etc.)
3. Functional design of the staged PMS (required stages and components, examples of products, staffing and resource requirements, cost estimates, etc.)
4. Recommendations and approval to proceed (report, presentations to senior officials of results of 1. to 3. above, modifications if necessary, final acceptance).

The pre-implementation stage should take no longer than two or three months and would normally range in cost from about $10,000 to $30,000 depending on the type of client, nature of the job, etc. It is desirable that such pre-implementation be carried out by a group with comprehensive knowledge and experience in the pavement management field. The results should be “stand alone” in that they can be used for the actual implementation by the client’s own people (i.e., in-house), or by another consultant.

Size of Agency and the Usefulness of Pavement Management

Good pavement management is certainly applicable and indeed necessary at the State level. In fact, even Canada’s smallest Province, PEI, implemented one of the mast comprehensive systems in North America several years ago for its network of highways (6). This network is comparable in size to the average District in a State Highway Department.

Cities and counties of various sizes, ranging from only a hundred or less miles of roads and streets to over a thousand, have either made excellent use of a well developed and smoothly functioning pavement management system (7, 9) or are currently implementing a PMS, such as Pima County and the City of Phoenix in Arizona.

Thus, the size of agency should not be a deterrent to the useful-ness or applicability of pavement management. The scale may differ but the principles are the same from the State level through to small cities or counties.

Benefits to be Expected, and Costs

The benefits to any agency should generally include better chances of making the correct decisions, better use of available funds, improved coordination and use of technology and better communication (2). For senior management, these benefits can be more specifically identified to include the following:

1. A comprehensive, comparative assessment of the current status of the network.
2. Objectively based answers to:
   (a) What level of funding is required to keep the current status, or
   (b) The implications of greater or lesser budgets.
3. Being able to justify capital and maintenance program recommendations to the elected council, or legislature.
4. Having the assurance that the recommended program represents the best use of available dollars.

There are also benefits for elected representatives and they can include the following:

1. The program of pavement maintenance and rehabilitation is defensible;
2. It represents the best expenditure of the tax funds; and,
3. It may in fact put less pressure on them to make arbitrary program modifications.

Turning to costs, and using a county example, they might expect to pay between about $50 to $150 per lane-mile per year for a Stage 1 to 3 type of PMS, depending on size of network involved, whether its a first time or update run, the field tests required, traffic conditions, types of reports and recommendations desired, etc. For example, if an 800 lane-mile network at $50 per lane-mile were involved, the annual cost would be $40,000. This would represent an annual management fee” on the investment of about ~, to 17, (assuming a value of $80,000 to $320,000 per lane-mile).

The project level of pavement management of course costs more because this is where the normal engineering fees for detailed testing, design, quantity estimates, contract preparation and supervision, quality control, etc. are incurred.

The Private Sector Role in Pavement Management

The main users of pavement management are of course the State and the cities and counties. But the private sector (i.e., contractors, suppliers and consultants) also has a role.

Any contractor or supplier should not suffer when the client spends dollars in a cost-effective way. In fact they should benefit could mean less work and materials; as well, scheduled program of work provides stability suppliers know what’s ahead and can themselves plan accordingly.

Consultants can play a direct role in that they can provide testing, engineering and computing services. In fact, if they have sufficient experience and expertise, [heir services can be particularly valuable and more cost-effective than doing the work in-house.

However, particular caution should also be exercised. Since the tremendous popularity of pavement management all across North America in the last few years, a lot of “instant experts” have come forward. Pavement management is not easy, it requires a lot of technical knowledge, resources,facilities, at,., and it doesn’t consist of nice, easy-to-use black boxes or off-the-shelf methods. It has to be tailored to each individual client’s situation and requirements. Consequently, while good use can certainly be made of consultants, their credentials and because wasting dollars a carefully planned and in that contractors and experience in pavement engineering and technology should be carefully assessed. The following section further addresses the role of consultants.

ROLE OF CONSULTANTS

The obvious questions for any agency contemplating the use of consultants for PMS implementation would include the following: why hire a consultant; what are the potential advantages and disadvantages; who should we consider and how should we evaluate them; how do we prepare clear terms of reference; how do we ensure control and getting what we want and need?

The reasons for hiring a consultant (i.e., the potential advantages), can include the following:

1. Obtaining specialized expertise, and outside experience, in PMS development and implementation,
2. Obtaining outside objectivity,
3. Getting the implementation done if insufficient internal resources exist (i.e., equipment, software, people, etc.) or accelerating it,
4. Lower overall cost.

Potential disadvantages can also exist, such as the possibility of getting a less qualified consultant than possible, less control on the work, etc.

Turning to the question of who should be considered and how- should they be evaluated, the first part can easily be done by asking other agencies, professional organizations, etc., who they know of in this field. It may be informal but is simple and effective. Evaluation is a bit more difficult, and can be done in two parts: (a) screening by asking for a statement of qualifications, or screening by actually carrying out an evaluation, and then (b) asking for a sole-source proposal, or evaluating proposals from qualified consultants (which assumes that terms of reference or request for proposals, RFP, have preceded). A convenient procedure for actually carrying out a consultant evaluation is given in Table 1. If this is used, and backup information or examples are obtained from the consultant for the various questions, then the most qualified one(s) can be identified fairly quickly.

TABLE 1	Yes	No	?
CONSULTANT EVALUATION PROCEDURE A. PAVEMENT MANAGEMENT 1. Is their PMS fundamentally sound, and practical? 2. Does their interest and expertise cover both network and project levels? 3. Will their PMS really assist us, administra-tively and operationally? 4. Are their programs and procedures such that we will know at all times what is going on, through regular consultation? 5. Is there provision far client input during implementation, and support afterwards? 6. Is the PMS sequential and modular to allow for maintenance, future updates and client operation? 7. Can the PMS be tailored to a client’s specific needs? 8. Can and will the firm do a pilot implementation on a portion of the client’s network? B. EXPERTISE AND PERSONNEL 1. Do they have sufficient years of experience in pavement evaluation, design and management? 2. Is pavement management their primary business? 3. Do they have known and respected senior professionals with sufficient experience and training? 4. Have their people contributed in a meaningful way to professional and technical organizations? 5. Have their people been recognized by awards, citations, etc., in the pavement management field? C. FIELD AND OFFICE EQUIPMENT 1. Is their PMS based on objective field data? 2. Do they have sufficient equipment to evaluate a11 pavement performance parameters? 3. Do they have sufficient computer equipment and staff to handle field data? 4. Does their computer hardware and software capabilities allow for flexibility in data treatment? 5. Have they shown initiative in developing equipment, software packages, new techniques, etc. D. SOFTWARE AND DATA ANALYSIS 1. Can they do performance prediction modelling, tailored to region and agency; are the procedures sound? 2. Do they work with objective data, such as roughness, surface distress, deflection, skid, geometrics, etc.? 3. Can they take into account such factors as subjective u opinion, alternative rehabilitation strategies, budget variations, user costs, etc.? 4. Does their priority analysis produce a truly optimized program of work and can it allow for testing of different budget levels? 5. Can the analysis results be provided in graphic. and tabular formats tailored to the needs of different users? 6. Will they provide user manuals for specific programs? 7. Will they install a data bank and ancillary software on the client’s computer? E. COST AND TIME FRAME 1. Does their priority analysis take into account deferral of work and timing alternatives? 2. Do they have the staff and in-house facilities to implement a complete PMS within one year? 3. Can their system be “tailored” to our needs and operated by our people after training? 4. What are the costs of the specific products and services they can provide, and what would it cost us to run the PMS in terms of people, hardware, software, etc.? F. TRACK RECORD 1. Can they provide evidence of growth and financial stability? 2. How many proven pavement management systems have they actually implemented? 3. Do they have experience with systems of different size and complexity? 4. Do they have a PMS which is technically up to the leading agencies and state of technology in the field? 5. Can they document and describe the steps in any work done for the client? 6. Can they provide testimonials from clients as to their work on various pavement management projects?

Clear terms of reference or RFP’s are essential to consultants

if they are to prepare a good proposal. This requires careful thought on the part of the client as to what they want, what they can provide in terms of resources and what money they have available. A good way to proceed is by stages, where, after screening of consultants,a pre-implementation RFP is firstly put out. This respesents a modest expenditure and allows for a “go” or “no go” decision at the end of the stage.

Similarly, control can be exercised on the project by incorporating decision points after each stage and by having a steering committee to meet regularly with the consultant.

Some Irritants from the Consultant’s Viewpoint

Among the most common irritants or problems consultants face are the following:

1. When-the client says “we can do it cheaper”. On a total accounting basis this is rarely if ever the-case. Consultants face stiff competition and they have to run an efficient operation to survive. As well, people who make the above statement usually forget any cost items that don’t come directly out of their budgets, but which nevertheless have to be paid for by the taxpayer.
2. Asking for proposals from a large set of consultants. This is wasteful and inefficient. It is not uncommon to see 10 or 15 proposals on a fairly small job. Consultants have to recover the costs of preparing these proposals from somewhere if they are to stay in business, and it is reflected in their prices. Why not do a screening and then invite the 3, 4 or 5 most qualified consultants to submit proposals?
3. Asking consultants for interviews with no consideration of costs, size of job, etc. Not too long ago, a city asked four firms to come for 15 minute interviews, after their proposals had been reviewed. The size of job was $30,000. Because they a11 had to come from some distance, the actual cost to each in terms of travel and time was about $2,000. Thus, the total interview costs alone to the consultants, aside from the costs of preparing the proposals, was $8,000, which is ridiculous when compared to the size of the job.
4. Asking consultants for a proposal, but not giving out a contract. There are few consultants who have not been “burned” in this way, where the prospective client either did not have the money approved to start with, or never did have any intention of hiring the consultant.
5. Assuming that the consultant can do extras for nothing. Some clients are very prone to ask for all kinds of extras and do not appreciate that there is a very fine line between profit and loss on almost all jobs. A 10% profit is, for example, quite common, which means that a $10,000 profit on a $100,000 nroject can very quickly “evaporate” if the client asks for free extras, or if there is any kind of overrun.

GETTING STARTED IN PAVEMENT MANAGEMENT

“How do we get started” is the first question from those making a decision to get into pavement management. While a comprehensive set of implementation guidelines is available (2, 3), the key to getting started is a pre-implementation stage (see Figure 3) if at all possible, including a plan of field inventory measurements. Good inventory data is the foundation for good pavement management., This would apply to either doing the work in-house, hiring a consultant, or some combination of both.

The inventory can include measurements for and evaluation of (a) structural adequacy, (b) ride quality, (c) surface condition and (d) skid resistance. It should also include data on: (e) geometrics and layer thicknesses, (f) rehabilitation and maintenance costs, and (g) traffic.

The inventory data provides a means for assessing the current status of the network, and identifying current needs, in Stage 1 (Figure 3). It also provides a basis for predicting when currently adequate sections will reach an “action level” in the future. This requires the development of a performance prediction method.

But what about setting up the inventory plan? How much of the network should be covered and with what measurements and frequency? What equipment and manpower are required, and/or should outside help be sought? How is the data to be handled? [Shat are the costs: Specific answers to these questions depend upon the available resources and management needs of each particular agency; thus the importance of the pre-implementation stage. Considerable experience has been accumulated which points out that the inventory can be staged and tailored [o the agency. Anyone getting started in pavement management would be wise to look at the experience of others and to examine the feasibility of bringing in outside expertise and/or help.

Let’s consider the questions of equipment and manpower require-ments, and costs, a bit further. A large highway department might buy much of its own deflection, roughness, skid, computer and other equipment, and be able to hire people to work mainly on pavement management. Conversely, a city or county might purchase all the required services. While size of organization certainly has an influence, what’s really important is the unit cost of doing the work and management use of the inventory data.

In summary, a pre-implementation stage with a good inventory scheme is the key to getting started. But it is not sufficient by itself. It should 6e part of a carefully developed and staged overall implementation plan, with “stand-alone” and useable products at the end of each stage.

REFERENCES

1. Haas, Ralph and Don Kohl, “Pavement Management: Why It’s Important and How to Accomplish It”, Paper Presented to APWA Kansas City, Missouri, Sept., 1980 .
2. Roads and Transportation Association of Canada, “Pavement Management Guide”, RTAC, Ottawa, 1977
3. Haas, Ralph and W. Ronald Hudson, “Pavement Management Systems”, McGraw-Hill, 1978
4. Karen, M.A., K. Longenecker, A. Stanley and Ralph Haas, “Implementation of Idaho’s Pavement Management System”, Paper Presented to Transp. Res. Bd., Washington, D.C., Jan., 1983
5. Karen, M.A., T.J. Christison, A. Cheetham and G. Berdahl, “Development and Implementation of Alberta’s Pavement Information and Needs System (PINS)”, Paper Presented to Transp. Res. Bd., !,’ash., D.C., Jan., 1983
6. Karen, M.A., Ralph Haas, and Thomas Walker, “Illustration Pavement Management, from Data Inventory to Priority Analysis”, IRS, Res. Record 814., 1981
7. Karen, M.A., Ralph Haas, D.A. Kobi and A. Cheetham, “Implementa-tion and Verification Examples of Successful Pavement Manage-ment”, Proc., Int. Conf. on Structural Design of Asphalt Pavements, Univ. of Mich., 1982
8. Haas, Ralph and Alan Cheetham, “Combined Priority Programming of Maintenance and Rehabilitation for Pavement Networks”, IRB, Res. Record 846, 1982
9. Smeaton, W. Kirk, G.A. Thompson, Clare Bauman and M.A. Karen, “The Payoff in Long-Term Management of the Investment in Paved Road Networks”, Paper presented to RTAC, Halifax, Sept., 1982

This was published in the Municipal Management, a Journal, Spring 1983, Vol. 5 No. 4.

By Dennis Polhill, P.E.

Dennis Polhill is president of Pavement Management Systems, Inc., a company that evaluates existing pavement structures and makes recommendations for maintenance and rehabilitation. He is a civil engineer and was a city engineer for ten years.

How can a city or town decide the best way to use what money it has available for repairing its infrastructure?

Three trillion dollars is needed to restore the United States’ infrastructure.

The infrastructure is all of the physical public works facilities which support the way of life, standard of living, and economic vitality which the U.S. has come to enjoy.

Investment in public works has declined at a rate of 4 percent per year. From 1965 to 1977 investment in public infrastructure declined 44 percent. Construction costs have inflated at twice the rate of consumer prices. Two thirds of the local governments in the U.S. cannot accommodate growth.

In a recent address, Representative Don Clawson of California suggested that “the pork-barrel mentality” of cutting capital projects in times of budget crunch is jeopardizing the economic vitality of the nation. Economic growth requires both an active public works and a strong transportation system.

The steady deterioration of the U.S. infrastructure is receiving increasing attention. Within the last year, leading news magazines have featured the problem; books have been written about it; TV documentaries have been aired about it; Congress has proposed legislation; and professional organizations have appointed study committees and issued position statements.

Best estimates of the infrastructure repair bill set the cost at $3 trillion. Some of the estimates that contribute to the $3 trillion figure are:

• $1,800 billion for roads and streets
• $33 billion for interstate highways (repairs only)
• $700 billion for non-urban highways
• $48 billion for bridges
• $110 billion for water systems in 750 major urban areas
• $40 billion for mass transit
• $31 billion for wastewater treatment
• $15 billion for prisons and jails
• $600 billion for city streets

John Wiedeman, president of the American Society of Civil Engineers, says “Virtually every part of the country has its own horror story. The full extent of the challenge of decaying public works is not yet known.”

• Poor roads cost the private sector $30 billion per year (Gasoline consumption increases 56 percent; tire costs increase 150 percent).
• Numerous lives are lost each year in accidents caused or aggravated by poor road conditions.
• In 1980, New York City paid $20,000,000 in liability claims for negligent maintenance.
• In 1980, $3,500,000,000 was paid by states in liability claims for negligent maintenance.
• 250,000 bridges (46 percent) are structurally deficient.
• 130 dams in highly populated areas are in danger of imminent collapse.
• 9,000 dams in highly populated areas are unsafe.
• 8,000 miles of interstate highway must be rehabilitated.
• 2,000 miles of interstate highway are wearing out each year.

Horror stories

Although these cost figures and horror stories are nationwide in scope, the concepts apply to every state, to every county, and to every city and town in the United States. Every governmental agency must develop an action plan which includes:

1) Inventory to determine the present condition of facilities and rank needs on the basis of objective criteria.

2) Financing to have sufficient resources to address the identified needs.

3) Implementation to ensure that financing is utilized efficiently and that resources committed to inventory efforts are not wasted.

Robert H. Gooden, director of public works for Rockville, Maryland, and chairman of the APWA Committee on Revenue Shonfall, states, “Only proper maintenance and operation of facilities will assure that the planned service life will be realized. While with adequate care facilities can serve well beyond their service life, at some point almost every public facility will require replacement…”

The most significant investment owned by cities and counties is their pavement facility. It is more valuable, contributes more direct benefit to economic efficiency, and has a higher cost of replacement than sewer systems, water systems, public buildings, and treatment plants. Citizens are also more aware of the condition of pavements than of other infrastructure needs.

Research has shown that performance of pavement declines as the pavement ages, as illustrated in Figure One. Differing pavement structures, traffic loads, soil and environmental conditions, and maintenance practices affect the shape of this curve. Conceptually, however, the curve is always the same; the older the pavement gets, the more rapidly it deteriorates and the more it costs to repair.

The process of inventorying and evaluating pavement systems is complicated because several pavement parameters are important: strength, roughness, surface distress, skid resistance, and rutting. Governmental agencies are interested in maximum service as measured by all of these parameters but, under economic restraints as they exist today, cost is an overriding concern.

Scientific methods are now available for inventorying and making pavement decisions that can result in enormous cost savings.

Overlay decisions

To illustrate the cost significance of these decisions, take the typical overlay decision. The decision “to overlay” involves a myriad of decisions which affect cost and performance:

• How thick should the overlay be?
• When should it be placed?
• When will the next overlay be required?
• What material(s) should be used?
• What alternates to overlay are available and viable (recycle, fabrics, etc.)?

Concerning the thickness decision, too-thin overlay will fail prematurely and too-thick overlay will cost more money than is necessary (and restrict a community’s ability to deal with another need). Asphalt concrete costs about $40 per ton in-place, which is about $63,000 per two-lane mile for a two-inch thickness. If a 1 3/4 inch thickness can serve as well, a city can save $8,000 per mile.

Similarly, if two inches extends service by eight years and 2 1/4 inches would extend service by 16 years, trying to save the one-fourth inch (or $8,000) costs your city $55,000 in eight years, plus an accelerated reconstruction schedule to restore crown and curb height.

If the judgments of your engineer are 90 percent accurate, he is costing your agency about $10,000 per mile. Generally, judgment decisions are no better than 50 percent accurate. Agencies which do not use systematic and scientific methods of managing pavements are costing their taxpayers a lot of money.

The decision concerning the best treatment for a specific street must, of course, be tempered by the needs of the entire street network. In other words, treatment “D” may give 10 units of benefit for each dollar expended on Colorado Street; but what about Main Street? The optimum treatment on Main Street may yield twelve units of benefit for the same expenditure of dollars. The process of making individual projects compete with each other to receive priority for rehabilitation is called network level optimization.

Complex process
This process is complex. Optimum priorities may change from year to year because of different performance curves. In other words, Main Street may yield more benefit one year but Colorado Street may yield more benefit another year. To do network level optimization, all possible combinations for each year of a programming period must be computed and compared. These calculations require computerization. A management system with this level of sophistication has the capability of testing several policy-level “what if” questions.

Figure Two shows how maintenance costs increase with time as the service level gets closer and closer to a minimum acceptable level. The end result is that a lower level of service is maintained at a higher cost than if rehabilitation was programmed at an optimum time.

This fact has been verified by several studies. One such study was done by the Utah Department of Transportation, which was referenced in NCHRP Report #58 (see Figure Three). For all categories of roadway, the least costly strategy was “A,” where the highest service level was sustained. The most costly was strategy “D” at which rehabilitation was deferred until substantial increases in maintenance activity were required in response to public pressure to sustain serviceability at a minimum acceptable level. Strategy “D” was UDOTs current mode of operation.

By using a system of network optimization, Ottawa, Canada, on the other hand, was able to reduce its road budget by 14 percent in actual dollars, which equates to 43 percent in inflated dollars while at the same time improving service levels.

Summary

• Pavement needs are enormous and growing due to past policies of deferring needed maintenance.
• The number of specific examples of infrastructure failure is increasing.
• Public works infrastructure must be inventoried, funded, and implemented.
• Pavements are our largest infrastructure investment.
• Research has produced performance curves for pavements.
• Scientific management of pavements can result in substantial cost savings.

This article is reprinted from Colorado Municipalities/January-February, 1983 with permission.