Communication product updates.
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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 firstname.lastname@example.org), or the National Transportation Library at ntl.bts.gov (or email email@example.com).
Updating HEC-18 Pier Scour Equations
For Noncohesive Soils (Report)
Publication Number: FHWA HRT 16-045
Balancing safety and cost is critical to smart investment when estimating scour at bridge piers in noncohesive soils. This report summarizes a study to improve techniques for estimating scour under a broad range of conditions using quantitative measures of reliability and accuracy. The researchers focused on situations with higher uncertainty, including sites with coarse bed materials and bridge designs with pier groups. The study, conducted at FHWA's J. Sterling Jones Hydraulics Laboratory at the Turner-Fairbank Highway Research Center, aimed to provide improved guidance to bridge engineers involved with foundation design.
Researchers compiled a dataset of 594 bridge pier scour observations from 2 laboratory and 3 held studies. The dataset served as the testing ground for evaluating potential enhancements to the pier scour tools for noncohesive soils in Hydraulic Engineering Circular 18 (HEC-18). The current (fifth) edition of HEC-18 provides two primary equations for pier scour in noncohesive soils. One is the general equation applicable to most situations, including clear water and live bed conditions. The second is a coarse bed material equation recommended only for use under clear water conditions with coarse bed materials. The objective of this research was to determine if the coarse bed materials equation could be used for conditions beyond those to which it is currently limited, including live bed conditions (for example, the movement of sediment during storm events). To do so, researchers developed a framework for evaluating the equations using qualitative and quantitative tools.
To analyze the equation currently limited to use with coarse bed material, researchers partitioned subsets of the available data based on key conditions, including coarse bed criteria, gradation, and median grain size. The equation performed reasonably consistently in all partitioned datasets, leading to the conclusion that it may be used for a broader range of conditions. The study also assessed a subset of pier group scour observations to determine whether the equation also could be used for pier groups. The equation performed better for single piers but offered a basis for predicting local scour at pier groups.
Considering these findings, the researchers recommend the modified equation for use on a broader range of noncohesive soil conditions for pier scour. The document is available to download at www.fliwa.dot.gov/publications/research/infrastructure/structures/bridge/16045/index.cfm.
Investigating the Impact of Lack Of Motorcycle Annual Average Daily Traffic Data In Crash Modeling and the Estimation Of Crash Modification Factors (Report) Publication Number: FHWA-HRT-16-054
Motorcycle crashes, which account for more than 14 percent of all motor vehicle fatalities, continue to be a significant safety concern on U.S. highways. Developing safety performance functions (SPFs) and crash modification factors (CMFs) that measure the safety effectiveness of highway safety improvements requires data on traffic exposure. The analysis of motorcycle crashes can be especially challenging in this regard because few jurisdictions collect motorcycle traffic volume data systematically.
This report discusses a research project conducted to address this challenge. The project involved performing several analyses to explore how much predictive power for an SPF is lost when motorcycle volumes are unknown and how this lack of information may affect the development of CMFs for motorcycle crashes. The project also explored alternative methods for deriving accurate predictions of motorcycle crashes or motorcycle volumes.
Results of the analyses show that when motorcycle volumes are not known, using total average annual daily traffic on its own is sufficient for developing SPFs and CMFs. However, the project team's attempts to predict motorcycle volumes based on typically available roadway and county-level data were largely unsuccessful.
A more significant issue in developing motorcycle crash SPFs and CMFs is working with relatively rare crash types. In the analyses undertaken, SPFs could not be developed for all motorcycle crash types or site types. In estimating CMFs using simulated data, the CMF value varied significantly between simulation runs because of the low frequency of motorcycle crashes.
The report identifies several research gaps related to analytical methods and data limitations. This effort identified the need for a database that includes implemented countermeasures expected to affect motorcycle crashes, along with the location, date of treatment, and treatment description. This information would aid researchers in identifying treatments that are feasible for study.
The document is available to download at www.fhwa.dot.gov/publications/research/safety/16054/index.cfm.
Implementation of Remaining Service Interval Concept (TechBrief) Publication Number: FHWA HRT-16-066
This TechBrief discusses a research project focused on demonstrating and validating with real data the application of the concept of remaining service intervals for pavements. The document describes the concept and then addresses the following key questions: Does the concept work? How can applying the concept of remaining service interval benefit highway agencies? What do agencies need to do to implement the concept?
Remaining service interval is based on the idea that pavement maintenance and rehabilitation requirements cannot be defined by a single value representing the end of life of the pavement. Instead, pavements should be described based on intervals used to communicate the amount of time before a treatment type is required to provide acceptable or above acceptable level of service at the lowest practical life-cycle cost.
The remaining service interval concept does not provide an alternative to assessing the health of the network or making decisions about how to spend available hinds. It simply provides clear terminology and a logical process that will create a consistent construction event-based terminology and understanding. An added benefit of adopting the remaining service interval terminology is that it provides a readily available way to communicate impacts of alternate budget scenarios.
The concept unifies the outcome of different approaches for determining needs by focusing on when and what treatments are needed as well as the service interruption created. The concept uses a structured sequence of maintenance, preservation, rehabilitation, and replacement actions through life-cycle cost considerations to provide acceptable service over the life cycle of the assets at minimum practicable cost.
Results from the validation efforts support the conclusion that the remaining service interval represents a valid approach to determining and communicating the flit Lire maintenance and rehabilitation needs of a pavement. Optimal pavement management decisions should not be predicated solely on condition-based threshold values for treatments, but instead may include the application of treatments well before a threshold condition is reached, in order to minimize life-cycle costs.
This document is available to download at www.fhwadot.gov/publications/research/infrastructure/pavements/16066/index.cfm.
FHWA Research and Technology Evaluation Program Summary Report Spring 2016 (Report) Publication Number: FHWA HRT-16071
The Federal Government has the responsibility to fund and conduct research and technology (R&T) activities of national interest that will lead to solutions to highway transportation issues. These efforts aim to significantly advance technological innovation with a clear public benefit when private investment is neither present nor sufficient. In 2003, FHWA leadership adopted a strategic-management framework called the Corporate Master Plan (CMP) for Research and Deployment of Technology & Innovation. Performance evaluation and measurement together form a major part of the CMP.
FHWA shapes and executes a national R&T program comprising eight research components. Four of these components take place under the guidance of the Turner-Fairbank Highway Research Center in McLean, VA. The research center's leadership has adopted a strategic plan to guide the center's continued development and capitalize on its significant accomplishments. The research evaluation efforts described in this report focus directly on goal 5 of the strategic plan, which specifies that research activities and outcomes are appropriately advanced through effective alignment of resources, dissemination of knowledge, and technology transition.
In support of the CMP and the strategic plan, FHWA's R&T program developed a research agenda to communicate to external customers, stakeholders, and within FHWA; provide a means for input and comment across the entire FHWA R&T portfolio; open opportunities for greater coordination of and collaboration on research and development; provide support system performance measures; and guide the investment of FHWA resources.
This report furthers the research agenda, summarizing 16 evaluations currently being conducted by staff at Volpe, the National Transportation Systems Center, and sponsored by FHWA's R&T program. The evaluations are grouped into two waves. The first wave consists of six retrospective and four prospective evaluations, while the second wave involves six prospective evaluations.
This report should be of interest to program managers, office directors, and executives within FHWA, as well as others within USDOT or other parts of the Federal Government interested in the outcomes and impacts of FHWA research.
The document is available to download at www.fliwa.dot.gov/publications/research/randt/evaluations/16071/16071.pdf.
Compiled by Lisa A. Shuler of FHWA's Office of Corporate Research, Technology, and Innovation Management
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|Author:||Shuler, Lisa A.|
|Date:||Mar 1, 2017|
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