|FHWA > Engineering > Construction > Quality > FHWA-HIF-07-012 > The Case for Performance Standards|
Highway Quality Compendium
The Case for Performance Standards
by Cheryl Allen Richter
Ambitious, but achievable, expectations are the first step to improve safety, to reduce construction-related congestion, and to enhance quality.
What if the highway community were to gauge the success of a highway construction project not from the perspective of engineers and public officials, but from the perspective of highway users? What might standards for customer service in the areas of safety, construction-related congestion, and quality look like? What if the government agencies and contractors responsible for highway construction were to use customer-focused performance standards-standards addressing characteristics such as smoothness, noise, longevity, and congestion-to define the highway infrastructure without being prescriptive about how it is built? How might such standards contribute to achieving a highway community that is more focused on meeting the needs of users and more open to new technologies that can improve highway safety, reduce construction-related congestion, and enhance the quality of our highway infrastructure?
The Federal Highway Administration (FHWA) has identified customer-focused performance standards as one measure that could contribute to significant advancement in highway construction practices.
Specifications Versus Performance Standards
While specifications define or provide a recipe for getting to a specific final product, performance standards tell what level of performance is expected for that product and then leave it up to the targeted organization to work out how to get there. In essence, performance standards represent a step beyond end-result specifications. The primary benefit is that an organization is allowed to use its expertise and experience to come up with innovative ways of obtaining the desired performance, rather than simply doing what has always been done before.
Skeptics who doubt that performance standards can be used effectively might look at the relationship between the Federal government and the automobile industry. Although the Federal government does not dictate specifically how manufacturers build their cars, several agencies are involved with making sure those vehicles are designed and built to certain levels of performance.
For example, the National Highway Traffic Safety Administration is charged with maintaining crashworthiness standards, so the agency developed standards such as the frontal crash compliance test, which calls for a
The U.S. Environmental Protection Agency (EPA) regulates standards for motor vehicle pollution. As EPA's Office of Mobile Sources indicates on one of its Web sites (http://www.epa.gov/otaq/invntory/overview/solutions/vech_engines.htm), EPA standards direct how much pollution autos may emit, but automakers decide how to achieve the pollution limits. The emission reductions of the 1970s came about because of fundamental improvements in engine design, plus the addition of charcoal canisters to collect hydrocarbon vapors and exhaust gas recirculation valves to reduce nitrogen oxides. Car companies are left to determine how best to meet the standards while delivering the best value to their customers. The result is an automobile industry that is responsive to the needs of the public, yet free to make use of innovation and imagination to compete in the marketplace. The standards actually appear to drive quality up!
The highway infrastructure analog to the three performance standards for automobiles-crashworthiness, CAFE, and emissions standards-might be safety, quality, and congestion resulting from construction. As with the auto world, in highway construction, performance standards should not spell out a recipe for building a section of highway or a bridge, but rather give the contractor the levels of safety, quality, and the like that are expected, and then allow the contractor to use its own abilities to meet that challenge. Another important parallel is that it would not be sufficient to meet only one or two of the standards; safety, quality, and congestion minimization are all necessary to customer satisfaction.
Finally, although the focus here is on construction, it must be recognized that just as the production of safe, fuel-efficient, low-emissions automobiles begins well before the manufacturing process starts, highway construction projects that meet demanding standards for safety, construction-related congestion, and quality begin with plans and designs that consider the needs and behavior of highway users in addition to the host of issues and factors that affect the highway construction process and the quality of the end product.
Why Performance Standards?
The most obvious rationale for performance standards is reflected in the preceding discussion of auto safety, CAFE, and emissions standards. They work! Automobiles coming off the assembly line today are safer and more fuel efficient and produce fewer emissions than those built a decade or two ago, not because someone dictated how they should be built, but because the desired end result was defined, and the industry was given the freedom to innovate and figure out how that result could be achieved. Consequently, lives and fuel have been saved, and the air that Americans breathe is cleaner than it would otherwise be.
The success of the auto safety, CAFE, and emissions standards demonstrates that such standards are highly effective drivers of change. Faced with this success, why would the highway construction community not want to adopt a proven approach to addressing the pressing challenges of highway construction? Why not establish specific targets to drive improvements in safety, construction-related congestion, and quality?
Most would agree that making highways safer, reducing construction-related congestion, and improving the quality of our highway infrastructure are laudable and appropriate goals. But what-specifically-do these goals mean? To be meaningful, lofty goals such as these must be translated into specific targets-performance standards-that clearly define and communicate expectations for improved safety, reduced construction-related congestion, and improved quality. A performance standard can serve not only as a "target to shoot at" but also as a benchmark against which success can be assessed. As such, these standards can provide a basis for gauging the value of specific tools, materials, and technologies, and construction or contracting practices, and the success, strengths, and weaknesses of individual construction projects or groups of projects.
A side benefit of performance standards is that they bring the construction contractor into the customer satisfaction equation. Rather than simply giving a contractor a set of specifications and waiting for the contractor to build a highway in an information vacuum, the owner agency focuses the contractor's efforts on specific customer-related needs, such as minimal traffic disruption, speed of completion, smoothness level, quiet level of ride, or increased level of safety. Thus, the contractor and owner agency become a team aimed at satisfying the needs of the customer, rather than simply getting a road built.
Performance Standards in Practice
Although the proposed role for performance standards goes well beyond current highway construction practice, performance standards for highway construction are nothing new. Because pavement smoothness is widely recognized as important from a standpoint of both user satisfaction (no one likes to drive on a rough road) and long-term performance (because smooth roads last longer and are often of higher overall quality than rough roads), performance standards for pavement smoothness have seen widespread use. Most State highway agencies use smoothness specifications of one form or another. These specifications establish target values (standards) for smoothness as measured using standard engineering test methods that have been related to user perceptions. Many include incentives and/or disincentives to encourage achievement of the high levels of smoothness that result in reduced operating costs for highway users and reduced maintenance costs for the owner agencies. Current performance standards for smoothness and the results obtained with them are illustrated by examples from Arizona, Virginia, and Kansas.
For new construction, Arizona has a target International Roughness Index (IRI) value of 41, with smoothness expressed as IRI in inches per mile. Incentives are earned for values below 38, and disincentives are assessed for values in excess of 48.
For rehabilitation projects, the target, incentive, and disincentive values vary as a function of highway type, the nature of the work to be performed, and (in some cases) the smoothness of the existing pavement. Ranges are as follows:
Removal and replacement (as opposed to other corrective action) is required for smoothness values that exceed the target plus 45.
Incentives Earned. In general, typical pavement smoothness incentives paid by the Arizona DOT average approximately $7,500 per lane mile or approximately
Typical or Average Levels of Smoothness Actually Provided. Average contractors in Arizona produce IRI smoothness values in the mid 30s. Some very good contractors consistently achieve IRI smoothness values in the low 30s, with substantial areas often in the 20s.
Virginia has smoothness special provisions for new construction and maintenance resurfacing, with smoothness expressed as IRI in inches per mile. For new construction, payment of 100 percent is for an IRI between 55 and 70 inches/mile. Bonus payments are earned for achieving IRI values less than 55, and penalties are incurred for IRI values greater than 70, to a maximum of zero payment at IRI values greater than 160 inches/mile. Corrective action is required when the average IRI for a section exceeds 100 inches/mile.
For maintenance resurfacing, a maximum 10 percent bonus based on the AC surface cost is possible for interstate sections with an IRI less than 45 and for noninterstates with an IRI less than 55. Additionally, 100 percent payment is for interstates from 55 to 70, while noninterstates must have an IRI between 65 and 80 for 100 percent payment.
Unlike new construction projects, most resurfacing projects are tested prior to and after paving. These projects are either a straight overlay or a mill-and-replace. The before-and-after testing is used to determine the amount of improvement in ride quality. If the contractor is able to improve the quality by more than 30 percent, then the contractor is guaranteed 100 percent payment for ride.
Incentives Offered by These Specifications. For new construction, the contractor can receive an incentive of up to 5 percent based on IRI results. The amount of the incentive is based on the unit cost for all AC layers or the square yard unit cost for the PCC.
Maintenance resurfacing contracts allow up to a 10 percent bonus. This amount is based on the AC surface cost.
Typical or Average Levels of Smoothness Actually Provided. Virginia has been actively using a ride special provision since the late 1990s. Most of the ride data have been collected on maintenance resurfacing projects. With more than
In addition to improved ride quality, Virginia has seen other benefits through use of these special provisions. During the mix-design process, contractors are developing mixes that better balance mix production costs and level of effort to achieve good quality field placement. These mixes result in better ride, better density, less tendency to segregate, less permeability, and more liquid asphalt for durability. When the ride special provision is applied to the project, more attention to detail is given during the paving process through use of a materials transfer vehicle, continuous feed of material, no stopping of the paver, and proper rolling techniques. The use of the ride special provision provides initial monetary incentives to the contractor and longer lasting pavements for the taxpayer.
With smoothness expressed as profile index in millimeters/kilometer (mm/km), Kansas specifications, in general, require an average profile index of 475 mm/km or less per 0.1 km section as measured with a California-type profilograph, a wheeled instrument for measuring smoothness by amplification of any variations from the plane. For PCC pavements, a higher value of 710 mm/km is allowed for roadways with a posted speed of 45 miles per hour (mph) or less and ramps. For flexible pavements, an exception is made for ramps and acceleration and deceleration lanes, for which a profile index of 630 mm/km or less is required. In addition, PCC pavement areas within each section having high points with deviations greater than 7.5 mm and flexible pavement areas within each section having high or low points with deviations greater than 10 mm in a length of 7.5 meters are to be corrected regardless of the profile index.
Incentives Offered by These Specifications. Pay adjustments are based on the average profile index determined for the sections prior to any corrective work such as grinding. If the contractor elects to remove and replace the sections (or overlay flexible pavements) to meet the smoothness specification, pay adjustments will be based on the average profile index obtained after replacement or overlay. See tables labeled "Schedule for Adjusted Payment-Flexible Pavements" and "Schedule for Adjusted Payment-PCC Pavements" for pay adjustment schedules.
Typical or Average Levels of Smoothness Actually Provided. Although some fluctuation has occurred from year to year, Kansas has seen a substantial increase in the percentage of pavements built with high levels of smoothness (0 to
How Might Performance Standards Look?
In highway construction, "the devil is in the details," and so it is with performance standards for highway construction. Although the smoothness specifications discussed in the preceding paragraphs represent important and successful steps toward customer-focused performance standards, they address only one aspect of performance. A complete set of customer-focused performance standards would address not only smoothness (which might be thought of as one element of quality), but also safety, congestion, and other aspects of quality. Moreover, an effective set of customer-focused performance standards would be founded on extensive input and participation from stakeholders throughout the highway community. Criteria that might be considered in formulating performance standards include:
To be truly effective, standards should be set at a level of performance well above average, but within the bounds of what has been achieved with current best practices and technologies. That is, they should require that agencies and contractors strive for excellence without setting a goal that cannot be achieved.
Several candidate performance standards are identified in the tables labeled "Possible Performance Standards for Safety," "Possible Performance Standards for Construction-Related Congestion," and "Possible Performance Standards for Quality." Identification of these candidate standards was guided, but not wholly driven, by the criteria outlined above. Identification of appropriate, nonprescriptive standards and performance measures for overall quality and longevity is especially challenging because the most obvious measures require long-term monitoring of performance. In practice, it may be appropriate to identify a small number of surrogate "quality indicators" in lieu of true quality standards.
Application of the Performance Standards
How might performance standards be applied in practice? A good place to start, after completing the development of a preliminary set of standards through dialogue with highway stakeholders, would be to apply them on some pilot projects that include the collection of data prior to, during, and after construction to support evaluation and refinement of the performance standards.
Customer-focused performance standards have the potential to be a key driver of innovation in the highway construction business. Such standards could establish elevated expectations for achievement in the areas of highway safety, minimization of construction-related congestion, and highway quality, all of which are of vital importance to the users of the national highway system.
Cheryl Richter, P.E., Ph.D., is the pavement technical coordinator in FHWA's Office of Infrastructure. Prior to her current assignment, she served as the team leader for Portland Cement Concrete Pavement Research and Development and as part of the Long-Term Pavement Performance Program staff at FHWA's Turner-Fairbank Highway Research Center in McLean, VA. Prior to joining FHWA, she worked for the Strategic Highway Research Program and the New York State DOT. She earned her B.S. and M.S. from Cornell University and her Ph.D. from the University of Maryland. She is registered as a professional engineer in Maryland.
The author would like to thank Lorenzo Casanova, Ken Davis, and Kirk Fredrichs of the FHWA Virginia, Arizona, and Kansas Divisions for gathering information for this article.
For more information on performance standards, contact Cheryl Richter at 202-366-3039 or firstname.lastname@example.org.
Reprinted from Public Roads, May/June 2004.