Dennis Polhill

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

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 formerly a city engineer for 10 years.

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 Shortfall, 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 5y 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.

To delay addressing this issue is to make the problem larger. 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.