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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Public Roads - Summer 2020

Summer 2020
Issue No:
Vol. 84 No. 2
Publication Number:
Table of Contents

Communication Product Updates

Communication Product Updates


Below are brief descriptions of communications products recently developed by the Federal Highway Administration's 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 website at 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: 703–605–6050
Toll-free number: 1–888–584–8332

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

R&T Product Distribution Center
Szanca Solutions/FHWA PDC
700 North 3rd Avenue
Altoona, PA 16601
Telephone: 814–239–1160
Fax: 814–239–2156

For more information on R&T communications products available from FHWA, visit FHWA’s website at, the FHWA Research Library at (or email, or the National Transportation Library at (or email

Analysis Procedures for Evaluating Superheavy Load Movement on Flexible Pavements, Volume VI: Appendix E, Ultimate and Service Limit Analyses

Publication Number: FHWA-HRT-18-054

The movement of superheavy loads (SHLs) on the Nation's highways is an increasingly common, vital economic necessity for many important industries, such as chemical, oil, electrical, and defense. Many superheavy components are extremely large and heavy (gross vehicle weights in excess of a few million pounds), and they often require specialized trailers and hauling units. Often, SHL vehicles have been assembled to suit the load being transported, and therefore, the axle configurations have not been standard or consistent. Accommodating SHL movements without undue damage to highway infrastructure requires the determination of whether the pavement is structurally adequate to sustain the SHL movement and protect any underground utilities. Such determination involves analyzing the likelihood of instantaneous or rapid load-induced shear failure of the pavement structure.

The goal of this project was to develop a comprehensive analysis process for evaluating SHL movement on flexible pavements. As part of the project, a comprehensive mechanistic-based analysis approach consisting of several analysis procedures was developed for flexible pavement structures and documented in a 10-volume series of FHWA reports.

Volume VI of the series details the analysis procedures for investigating the risk of ultimate and localized shear failure under SHL-vehicle movements. The report also presents a deflection-based service limit analysis for limiting the amount of pavement surface deflection under an SHL-vehicle.

This report is intended for use by highway agency pavement engineers responsible for assessing the structural adequacy of pavements in the proposed route and identifying mitigation strategies in support of the agency's response to SHL-movement permit requests.

The document is available to download at

Simulator Assessment of Alternative Lane Grouping at Signalized Intersections (TechBrief)

Publication Number: FHWA-HRT-19-034

This technical summary presents the study results for research conducted in a highway driving simulator to evaluate driver behavior and sign comprehension during reversible-lane operations compared to conventional-lane operations.

Throughput at signalized intersections with high left-turn demand is a common cause of bottleneck for traffic flow. Dynamic lane-grouping strategies offer cost-effective methods for increasing operational efficiency within existing rights-of-way. Previous traffic simulations suggest that reversible left-turn lanes can significantly increase throughput at intersections where left-turn demand is high. However, the operational benefits offered by reversible-turn-lane designs depend on safe and proper use by drivers.

Because reversible lanes make use of existing infrastructure and are dependent on time of day, they require clear and adaptive signs and signals to indicate the active or closed status of a reversible lane and to control alternative-lane assignment during active periods. Reversible-lane designs may also expose drivers to unfamiliar situations, such as sharing a lane with opposing traffic waiting at the far side of the intersection. In these cases, appropriate signs can mitigate unsafe driving behaviors and driver discomfort or confusion. In addition, improved signs and markings may aid in minimizing issues observed at existing reversible-lane interchanges, such as incorrect or missed turns and lane changes within the intersection.

The document is available to download at