U.S. Department of Transportation
Federal Highway Administration
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Washington, DC 20590
202-366-4000
The Federal Highway Administration (FHWA) and the American Association of State Highway and Transportation Officials (AASHTO) conducted a study under the International Technology Scanning Program on the topic of superior materials, advanced test methods, and specifications. The study included visits to several European nations. During the visits, representatives of the United Kingdom, Denmark, Germany, and the Netherlands discussed their unique approaches to introducing, approving, and specifying new materials and manufactured products employed in highway construction. Issues discussed ranged from high-level policy issues to specific material evaluation procedures. The visits proved helpful in meeting the overall objectives of the scan, which ultimately will benefit the highway industry in the United States by identifying how processes for introducing new and innovative materials and products might be improved.
The scan focused on the use of superior materials in the highway infrastructure. For the purpose of this scan, “superior materials” were defined as those materials and manufactured products that do the following:
Furthermore, projects on which the superior materials can be employed include the following:
Over the past several years, most of Europe has seen a migration in process and specification. Many countries are transitioning from methods-based specifications, and are developing and adopting more functional requirements for their construction materials. Functional specifications are similar to end-result specifications used in the United States, but tend to incorporate elements of a performance specification. The objective of a functional specification is to ensure that the end product was constructed to meet the function for which it was intended (e.g., the noise level, smoothness, and safety that the public expects or demands). The use of these specifications and contracting methods has resulted in the introduction of more innovative materials, since a material that meets the specified function is deemed acceptable.
The formation of the European Union (EU) has had a profound impact on most facets of government. By working to eliminate barriers to free trade, the EU has created opportunities for vendors and owners to move toward standardized functional specifications rather than conventional prescriptive specifications. To assist in this effort, the European Committee for Standardization (Comité Européen de Normalisation, or CEN) was established to coordinate and manage the specification standards.
While the CEN standardization process is moving forward, it is not without difficulty. As part of the harmonization process, each member country must debate the details of its previously independent specifications. In addition to the CEN, the European Organisation for Technical Approvals (EOTA) provides a common testing and evaluation forum for products that do not have a standard specification.
Development of the CEN specifications can be contrasted with AASHTO specifications. While AASHTO has produced guide specifications that States may opt to adopt or modify, the EU is in the process of combining current specifications into a common binding specification for use across Europe. It should be noted that within the CEN, quality classifications allow for varying thresholds and tolerances on the material test results.
The Europeans used warranties and performance contracts as part of everyday practice. The specific elements of these contracts varied, ranging from short-term (1-to-3 year) materials and workmanship warranties to long-term (more than 30year) design-build-finance-operate (DBFO) contracts. While these types of contracts were common, levels of comfort associated with them varied. Some agencies appeared more willing to relinquish control because they have seen an obvious increase in quality, while others appeared more cautious in their adoption. The same was sometimes true in a given agency, where one division was more receptive to using warranties, while another was more averse. Another interesting finding was that each of the countries visited employed a performance-based component in its contract award process. This, along with other decision-making criteria, meant that the low bidder on the job was not necessarily the successful bidder.
While an increase in quality often resulted, innovation through the use of superior materials was not always realized merely because of a warranty mechanism. Their use was more common on longer-term warranties in which the contractor had more latitude in the materials and processes it could use. Where superior materials were used, it was found that the specifications were much more performance based. It was also found, however, that some difficulty remains in how to define the performance standard, including what to measure, how to measure it, and when it should be measured.
The scanning team observed a variety of models for product evaluation and certification. While most countries had well-established systems in place, officials stressed that European standardization was changing this with the EOTA process serving as the coordinated organization for considering materials for which no standard exists.
In the United Kingdom, the Highways Agency (HA) uses an innovative process termed the Highway Authorities Product Approval Scheme (HAPAS). Administered under an independent certification agency, the British Board of Agrément (BBA), the HAPAS process involves working with the private sector to establish functional specifications to replace conventional method specifications. Existing performance and quality data for a product classification is gathered from the private sector to assist in functional specification development.
For certification, a vendor presents its existing product data to the BBA. A formal evaluation process is initiated that, if successful, results in a BBA certification that the product meets the quality and performance intent of the specification. In British terms, the product is deemed “fit for purpose.” Trade secrets such as constituents and manufacturing details are not released, but instead sealed by the BBA for use during subsequent quality audits. The HAPAS process appears to be successful, eliminating the need for routine on-site testing and continual surveillance for these material categories. It also provides the vendor with confidentiality as well. Certifications are available to the agency or owner on the Internet.
Other testing and evaluation organizations include the Building Research Establishment (BRE) and Transport Research Laboratory (TRL) of the United Kingdom, Danish Road Institute (DRI), Bundesanstalt für Straßenwesen (BASt) of Germany, and Dienst Weg-en Waterbouwkunde (DWW) and the Information and Technology Centre for Transport and Infrastructure (CROW) of the Netherlands. These organizations are prominent, well respected, and trusted in the highway community. When a vendor desires consideration of a material by an agency or contractor (e.g., on a warranty job), it many times will seek the approval of one of these organizations.
In the Netherlands, transportation officials presented a novel approach to exploring long-range solutions for meeting future highway demands. A contest was held in which a number of highway functional requirements were defined, such as noise reduction and paving windows. To meet these demands, contractors were invited to offer solutions, no matter how unconventional. The agency was surprised by the tremendous response. It selected a small number of contractors for further evaluation on a highway test section. The contractors tried four techniques, including options with precast polymer surfaces that were laid down from rolls (like carpeting). This radical experiment resulted in a paradigm shift from the traditionally conservative thinking of the Dutch highway industry. Funding for this effort was equally divided between the agency and the contractors, resulting in both shared risk and reward. One of the more notable aspects of this experiment was the timeframe. The idea went from concept to final placement in 2 years.
The scanning team found that the highway community in the European countries, through the use of both accelerated load testing and various forms of field testing, evaluated superior materials for both properties and performance. The national testing laboratories with access to the requisite equipment and facilities, especially for the accelerated testing, commonly used these procedures. Vendors that wished to evaluate the performance of their product before seeking certification or specification sometimes initiated the demand for performance testing. Testing under accelerated loading allowed long-term performance to be assessed in a limited timeframe. In addition, because the conditions were carefully controlled, this eliminated much of the inherent uncertainty of a field trial on an active highway.
The various countries visited used a number of unique test methods for evaluating materials. While many have been used to some degree in the United States, the scan team believes that consideration should given to a renewed evaluation. These methods include the following:
The European hosts presented a variety of materials to the project team that met their definition of superior. Like the test methods, a number of these materials have been introduced in the United States already, but are listed here to highlight their more widespread use (in some cases) in Europe. The scanning team believes that some of these materials show promise for U.S. use as the pressure to better meet the needs and desires of the traveling public begins to dominate the decisionmaking process. Materials of interest include the following:
Additional observations include the following:
In the Netherlands, a novel approach to exploring long-range solutions for meeting future highway demands impressed the scan team. In a program called “Roads to the Future,” the government integrated long-term perspectives with short-term test projects and demonstrations through a cooperative, split-funded effort with industry. The intent of the program was to examine road surfaces of the future and to develop demonstrable concepts for tomorrow's road surface. The agency's other goals were to stimulate out-of-the-box thinking in both the agency and Dutch companies.
Because of the expense and logistics associated with field-testing of lane markings (stripes), Germany has developed a laboratory facility for accelerated lane marking evaluation. This facility is capable of evaluating tape, temporary paint, and permanent paint markings, and hot and cold plastic systems.
The scan team identified several key processes worthy of additional examination. They include the EU, the British HAPAS program, and the French Charter for Innovation. Each has potential merit for implementation in the United States.
The European public roads agencies face many of the same staff and funding cutbacks experienced by State departments of transportation (DOTs) in the United States. In addition, they seek both innovative and cost-effective execution of their maintenance operations. All four countries visited have experience with functional (performance-based) maintenance contracts. The United Kingdom is looking at awarding these contracts solely on quality. The Netherlands is working almost exclusively with these types of contracts and has moved to the second generation of specification. In Denmark, municipalities are beginning to use 10-to-15-year functional contracts for pavement surface renewal and restoration.
Materials and pavement engineers need guidance on rational approaches to addressing noise in pavement design, mix design, construction, and maintenance. This and other scans have identified noise generated in the highway environment as a problem of significant concern in Europe that requires innovative and sometimes expensive solutions. While U.S. DOTs have established procedures for designing and installing noise walls, only a few have addressed noise attributed to pavement type, material, construction, and maintenance techniques. Several DOTs are now addressing this problem, using modified pavement surface texturing such as diamond grinding or longitudinal tine texturing, or modified mixes such as crumb rubber, stone-matrix asphalt (SMA), or open-graded asphalt friction courses as noise-attenuating surfaces.
Drivers' expectations and those of abutters to the highways are different in Europe than they are in the United States, but with an increasing number of DOT material and pavement engineers considering noise, a more rational approach to pavement and mix design is needed to address the issue.
The scan team identified numerous products, specifications, and tests that the European countries are using or developing that may be of interest to DOT engineers in the United States. For a select number of these, we believe that the logical step is to collect additional European background information. After reviewing this information and comparing it to U.S. practice, researchers can identify potential benefits and develop a plan for possible introduction and evaluation in the United States. Items the team believes show promise include the following:
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