Official US Government Icon

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure Site Icon

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

The latest general information on the Coronavirus Disease 2019 (COVID-19) is available on For USDOT specific COVID-19 resources, please visit our page.

United States Department of Transportation United States Department of Transportation

Public Roads - Summer 2018

Summer 2018
Issue No:
Vol. 82 No. 2
Publication Number:
Table of Contents

Communication Product Updates

Communication Product Updates

by Lisa A. Shuler of FHWA's Office of Corporate Research, Technology, and Innovation Management

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 Web site 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 
Web site:

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 Web site at, the FHWA Research Library at (or email, or the National Transportation Library at (or email


Adjacent Box Beam Connections: Performance and Optimization


Publication Numbers: FHWA-HRT-17-093 (Full Report) and FHWA-HRT-17-094 (Tech Brief)

Precast, prestressed concrete adjacent box beams are widely used in short- and medium-span bridges in the United States. A recurring issue with this type of bridge is the deterioration of shear key connections, resulting in substandard performance of the overall bridge system. This report and technical brief present the results of research using full-scale structural tests to investigate four different shear key connection designs.

The designs include partial- and full-depth connections constructed with either conventional nonshrink grout or ultra-high performance concrete (UHPC). The researchers found that UHPC connections can be a resilient and innovative solution to prevent connection degradation in adjacent box beam superstructure systems, advancing the state of the practice in bridge construction.

The technical brief is available to download at The report with full results of the study is available at


Self-Enforcing Roadways: A Guidance Report (Report)

Publication Number: FHWA-HRT-17-098

The objective of this project was to develop guidance to identify methods that may produce self-enforcing roadways during the geometric design process. A self-enforcing road, also called a self-explaining roadway, is a roadway that is planned and designed, typically using geometric elements, to encourage drivers to select operating speeds consistent with the posted speed limit. The ideal is for operating speeds and posted speed limits to be in harmony with the roadway’s geometric design speed. While safety performance associated with these methods is not well understood yet, an implied outcome of effective speed management is that less severe crashes will result.

Speeding is a complex issue that involves many factors, including public attitudes, vehicle performance, posted speed limits, and enforcement strategies. Addressing the issue requires integration and coordination among many groups: engineering, enforcement, and education. The report describes six self-enforcing road concepts and the processes needed to implement them when designing or evaluating existing two-lane rural highways. The six methods are (1) the speed feedback loop process, (2) the inferred design speed approach, (3) design consistency methods, (4) applying geometric design criteria, (5) using a combination of signs and pavement markings, and (6) setting rational speed limits.

Highway engineers can apply these methods individually or in combination for planned or existing two-lane rural highways. The report examines implementation methods and presents two case studies of existing two-lane rural highways. As the application of self-enforcing roadway design concepts becomes more commonplace in the United States and elsewhere, FHWA recommends that future research be undertaken to evaluate the effects of these practices on speed and safety.

The report is available to download at