Below are brief descriptions of communications products recently developed by the Federal Highway Administration’s (FHWA) Office of Research, Development, and Technology. All of the reports are or will soon be available from the National Technical Information Service (NTIS). In some cases, limited copies of the communications products are available from FHWA’s Research and Technology (R&T) Product Distribution Center (PDC).

When ordering from NTIS, include the NTIS publication number (PB number) and the publication title. You also may visit the NTIS Web site at www.ntis.gov to order publications online. Call NTIS for current prices. For customers outside the United States, Canada, and Mexico, the cost is usually double the listed price. Address requests to:

National Technical Information Service
5301 Shawnee Road
Alexandria, VA 22312
Telephone: 703–605–6000
Toll-free number: 1–888–584–8332
Web site: www.ntis.gov
Email: customerservice@ntis.gov

Requests for items available from the R&T Product Distribution Center should be addressed to:

R&T Product Distribution Center
Szanca Solutions/FHWA PDC
13710 Dunnings Highway
Claysburg, PA 16625
Telephone: 814–239–1160
Fax: 814–239–2156
Email: report.center@dot.gov

For more information on R&T communications products available from FHWA, visit FHWA’s Web site at www.fhwa.dot.gov, the FHWA Research Library at www.fhwa.dot.gov/research/library (or email fhwalibrary@dot.gov), or the National Transportation Library at ntl.bts.gov (or email library@dot.gov).

Performance-Based Contractor Prequalification As an Alternative to Performance Bonds (Report)

Publication Number: FHWA-HRT-14-034

State departments of transportation often rely on construction contractors to build, rehabilitate, and replace infrastructure assets. This report discusses a study that evaluates a performance-based process for prequalification that can help DOTs select qualified contractors.

Researchers examined relevant literature and evaluated the benefits and costs of performance bonds, which are issued by an insurance company to guarantee satisfactory completion of a project by a contractor. The study examined performance-based contractor prequalification and recommended a more robust three-tiered model.

In the highway industry, one of the main methods to prequalify a contractor is to determine whether a performance bond can be secured. The current performance bonding system does not differentiate between a high-performing and a marginally performing contractor, as long as the two companies have the same level of financial assets. This gives both companies the same opportunity to bid on a project, regardless of performance. In a low-bid environment, the result may be a situation where a State DOT subsidizes marginal performance, which reduces the incentive for top performers to continue superior performance.

After a detailed review of case studies and surveys of contractors, State DOTs, and sureties, researchers found that the rate of default on performance bonds for the industry is less than 1 percent. The research team suggested that the minimum contract value that requires a performance bond be raised to somewhere between $1 million and $10 million from the current minimums set by each State’s bonding regulations. Researchers also found that the cost of performance-based prequalification is low compared to the cost of performance bonds.

This document is available to download at www.fhwa.dot.gov/publications/research/infrastructure/14034/index.cfm. Printed copies are available from the PDC.

Use of Radio Frequency Identification Tags in Pavements (Report)

Publication Number: FHWA-HRT-14-061

This report discusses a study evaluating how inexpensive radio frequency identification (RFID) tags can be used in a set of pavement construction applications. Researchers examined the use of RFID tags during construction to identify the spatial location along a roadway for placing truckloads of hot-mix asphalt and portland cement concrete.

In addition to tracking the placement of pavement materials, researchers studied applications for real-time measurement of pavement temperature versus depth and time during intelligent compaction, and early detection of reflection cracking in overlays. They also reviewed guidelines for integration of data on material property, construction, and pavement performance during service using RFID-assisted geolocation.

The first and second phases of the three-phase project addressed the development of techniques for making RFID tags sufficiently rugged to withstand the harsh thermal and mechanical conditions of hot-mix paving and for evaluating survival and read performance of the tags after construction. Researchers identified additional applications of RFID technologies to pavements for assessment. The additional applications include the evaluation of potential problems caused by surfaced tags and the exploration of surface acoustic wave RFID technology for improved performance of small format tags. The third phase of the project focused on evaluating these additional topics.

Researchers found that RFID tracking of hot-mix asphalt placement was the more successful application and the one with the potential for immediate commercial implementation. Tracking of portland cement concrete placement proved to be more of a challenge due to the dielectric properties of concrete. Other applications show promise but need additional research or development. Ongoing followup research funded by FHWA is focusing on expanding the data-gathering capabilities of RFID linked tags.

This report is intended for transportation engineers involved in pavement design, construction, and management, as well as quality acceptance testing of paving materials. The document is available to download at www.fhwa.dot.gov/publications/research/infrastructure/pavements/14061/index.cfm. Printed copies are available from the PDC.

Lightweight Concrete: Shear Performance (Technical Brief)

Publication Number: FHWA-HRT-15-021

Current provisions for lightweight concrete in the American Association of State Highway and Trans-portation Officials’ LRFD [Load and Resistance Factor Design] Bridge Design Specifications are based on research from the 1960s. The lightweight concrete that was part of this research used traditional mixes of coarse aggregate, fine aggregate, portland cement, and water. Over the past 50 years, broad-based advancement in concrete technology has enabled significant progress in the mechanical and durability performance of lightweight concrete.

The AASHTO specifications do not cover concrete with a unit weight between that of traditional lightweight concrete and normal-weight concrete. As part of an effort to address this and other perceived shortcomings in how the specifications address lightweight concrete and how lightweight concrete is deployed in bridges, FHWA conducted research to assess the shear performance of these concretes with varying densities. The research team completed 30 full-scale precast, prestressed girder tests and developed a database of shear performance results that covers a wide range of concrete densities. As a result, researchers developed proposed revisions to AASHTO’s LRFD Bridge Design Specifications as part of a framework that addresses the performance of structural concrete as a function of density. The AASHTO Subcommittee on Bridges and Structures recently debated, refined, and approved these proposed revisions, which will be reflected in future versions of the AASHTO LRFD Bridge Design Specifications.

This technical brief describes shear tests on lightweight concrete prestressed girders, summarizes the database of lightweight concrete and normal-weight concrete shear tests, describes a reliability analysis, and presents potential revisions to the LRFD Bridge Design Specifications relating to the shear resistance of lightweight concrete.

The document is available to download at www.fhwa.dot.gov/publications/research/infrastructure/structures/bridge/15021/index.cfm. Printed copies are available from the PDC.