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    <title>Transport Research International Documentation (TRID)</title>
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
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    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Transport Research International Documentation (TRID)</title>
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    <item>
      <title>Long-Term Construction and Maintenance Cost Comparison for Road Stream Crossings: Traditional Hydraulic Design vs. Aquatic Organism Passage Design</title>
      <link>https://trid.trb.org/View/1515590</link>
      <description><![CDATA[The design and installation of road stream crossings to accommodate fish and aquatic organism passage is increasingly becoming a priority for state and federal regulatory agencies throughout the United States to meet the mandates of the Clean Water Act, and in the case with federally protected migratory species, the Endangered Species Act. While progress has been made in providing fish passage at dams on many river systems, these agencies realize that road crossings are much more numerous than dams and may have a greater impact on fish passage than dams as supported by inventories of road crossings conducted to assess aquatic passage in the Pacific Northwest. In addition, extreme weather events and other climate change concerns are driving discussions toward a new paradigm for infrastructure investment decisions that considers the overall life-cycle costs of structures. The higher costs of installing effective aquatic organism passage structures are often a concern for designers and transportation agencies. While it is clear that the upfront costs of larger structures may increase with effective aquatic organism passage designs, long term savings may be achieved by reducing the risk of road failure, reducing the need for periodic maintenance, increasing the life span of the structure, and reducing the cost of mitigation for open water and wetland impacts. There are three general approaches to the drainage design of culverts that are in use across the nation, though variations in application occur: (1) Traditional or conventional hydraulic design; (2) Aquatic organism passage (AOP) design (HEC-26 and Bankfull width times a safety factor); and (3) Stream simulation design (geomorphic design). Multiple states and federal entities have developed guidance regarding stream crossing design approaches, but the guidance focuses primarily on design approaches mentioned above and design options. While design options have been studied, research is needed to evaluate the long-term costs and benefits of aquatic organism passage design which can support decision making on project design and funding. The objectives of the overall Task 93 project research are to: (1) Quantify the long-term costs of road stream crossings that span the bankfull width of a waterway (aquatic organism passage design) in order to provide an accurate picture of the total life-cycle cost of the structure; and (2) Compare costs of aquatic organism passage design-based structures to the costs of traditional hydraulic design structures.]]></description>
      <pubDate>Mon, 18 Jun 2018 12:26:54 GMT</pubDate>
      <guid>https://trid.trb.org/View/1515590</guid>
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      <title>Approximate simulation of storm water runoff over pervious pavement</title>
      <link>https://trid.trb.org/View/1448388</link>
      <description><![CDATA[The approximate simulation of storm water run-off over pervious pavement is carried out using both experimental method and numerical simulation. The slope and flow rate changeable flume and uniform porous media are used to approximately simulate the pervious pavement. A 3D computational fluid dynamics – discrete element method is used for numerical simulation of interaction between pervious pavement and fluid. The effects of variation of parameters, including inflow rate, infiltration outflow rate and slope on surface run-off are analysed. The average flow velocity within the surface run-off region and shear velocity increases with the increasing permeability of pervious pavement. The turbulent kinetic energy distribution along depth in the free-flow region is more uniform than empirical relationship for flow over impermeable surfaces. Equations for flow depth and velocity over pervious pavement have been deduced. The results of this study are helpful for the hydraulic design of pervious concrete pavement.]]></description>
      <pubDate>Sun, 19 Mar 2017 18:01:48 GMT</pubDate>
      <guid>https://trid.trb.org/View/1448388</guid>
    </item>
    <item>
      <title>Enhancements to the FHWA-FST2DH Model for Simulating Two-dimensional Depth-averaged Flow and Sediment Transport</title>
      <link>https://trid.trb.org/View/1328367</link>
      <description><![CDATA[The objectives of this research is to enhance the FHWA-FST2DH Model for Simulating Two-dimensional Depth-averaged Flow and Sediment Transport. The research will address the following needs: (1) Improve Equation Solution Schemes - Implement parallel versions of several popular iterative methods for solving systems of equations.  This will allow much faster computation times thus increasing productivity and the application of more complicated solutions to complex surface water flows. (2) Update and Testing of Sediment Transport Algorithms - Existing sediment transport algorithms will be tested using both hypothetical cases and comparison to measured data from both laboratory experiments and onsite studies of scour at river bends and constrictions (such as bridge openings).  Sediment transport formulas not currently included in the existing formula library will also be added. (3) Update of Bridge Pier Local Scour Calculations - Bridge pier local scour calculations will be updated to include the most recent HEC-18 procedures, as well as other optional local scour calculation methods not currently coded in the model. (4) Update FST2DH Manual that would include the following: (a) Descriptions of improved sediment transport algorithms. (b) An added appendix that describes sediment transport test applications and new sediment transport formulas. (c) An added appendix that describes use of new equation solution schemes. (d) An added appendix that describes solution parameter uncertainty estimate calculations and how they can be used in practical design of hydraulic structures such as bridges and river training works. (e) Conversion of current WordPerfect electronic format to Microsoft Word electronic format.  This encompasses much more than an import/export operation from either WordPerfect or Microsoft Word since all equations will need to be re-typed and the document will need to be reformatted completely.]]></description>
      <pubDate>Tue, 21 Oct 2014 01:02:06 GMT</pubDate>
      <guid>https://trid.trb.org/View/1328367</guid>
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    <item>
      <title>HDS 2-Peak Rates of Runoff from Small Watersheds</title>
      <link>https://trid.trb.org/View/1214051</link>
      <description><![CDATA[A problem in the design of bridges and culverts is that of estimating the volume of streamflow to be expected at peak periods. It has long been realized, among hydrologists, that differences in watershed area alone are insufficient to explain the wide variations in peak rates of runoff found to exist among watersheds. This is true even when these variations are limited to those within the boundaries of an area where the principal physiographic characteristics of watersheds are similar. While area alone has been found lacking as a measure of peak runoff, it has been discovered that if one or more precipitation indexes and some topographic index based on the length and slope of the principal stream channel were added to the watershed area factor as independent variables, the unexplained variation in the magnitude of the peak rates of runoff could often times be reduced to workable limits. Although this method was an improvement over the the results obtained by the consideration of watershed area alone, it still did not explain the large differences that many times occurred between some of the estimated peaks and the corresponding actual values derived from stream measurements. In these cases the differences might be no more than plus or minus 20 percent of the estimate for 68 percent of the gaged watershed sample, but would be over 100 percent for 5 to 10 percent of the sample. This would suggest the action of some additional variables that remained fairly constant for most of the gaged sample but differed significantly for the 5 to 10 percent. The research investigation reported here successfully determined the identity of these additional variables, and from there a procedure has been developed for predicting runoff peaks from small watersheds in most of the United States east of the 105th meridian, roughly, east of Denver, Colorado.]]></description>
      <pubDate>Wed, 19 Sep 2012 14:27:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/1214051</guid>
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      <title>Common Pitfalls in Hydraulic Design of Large Diameter Pipelines: Case Studies and Good Design Practice</title>
      <link>https://trid.trb.org/View/1113424</link>
      <description><![CDATA[When designing large diameter water transmission pipelines, some engineers rely on design rules-of-thumb or a previous project as a template, without recognizing the inherent differences of each project. For large-scale water supply projects, mistakes in hydraulic design, especially underestimating friction headlosses, can be magnified resulting in reduced system capacities, catastrophic failures, or potential litigation. One of the most common mistakes in hydraulic design of large-diameter pipelines is underestimating pipe resistance and friction headlosses. The Hazen-Williams equation is the most widely used method for calculating headlosses in pipelines because it is simple and easy to use. However, the Hazen-Williams equation is empirical and, for large-diameter pipelines, has a limited range of applicability. Conversely, the Darcy-Weisbach equation provides a better approximation of friction headlosses since it takes into account the pipe roughness and Reynolds Number for different pipe materials, and is valid for all pipe sizes and turbulent flow ranges. Although there is an abundance of evidence of the limitations of the Hazen-Williams equation, it is continually misused in the engineering industry. There are many other design issues that can cause serious performance problems with large-diameter pipeline projects if not taken into consideration during design. Additional common hydraulic design pitfalls include: underestimating effects of sediment and biological material in raw water sources, not accounting for aging of pipeline materials, inadequate pipe pressure class design, improper placement and sizing of air valves, lack of accurate transient and surge analysis, inadequate flow and pressure field measurement, and potential need for pipeline maintenance and cleaning. There have been numerous publications on the topic of hydraulic design and proper calculation of pipeline friction headlosses. However, the focus of this paper is to provide analysis through case studies of several major water supply systems that reaffirms the importance of utilizing proper hydraulic considerations. Common hydraulic design oversights and short-cuts can often result in capacity and maintenance problems for large water supply systems.]]></description>
      <pubDate>Tue, 21 Aug 2012 17:09:17 GMT</pubDate>
      <guid>https://trid.trb.org/View/1113424</guid>
    </item>
    <item>
      <title>Hydraulic Hybrid Vehicles</title>
      <link>https://trid.trb.org/View/869533</link>
      <description><![CDATA[This chapter describes how hydraulic hybridization is a solution for improving the fuel economy of heavier vehicles. It is cost effective, applicable today with off-the-shelf components, and has demonstrated greater savings than any other form of hybridization currently in use. The components are reliable and have been proven in years of experience in many industries. The results have been dramatic: the initial systems are proven at improving fuel economy by more than 25 percent in basic parallel hybrid systems and considerably more in series hybrid configurations. In addition, these systems produce much less pollution while improving vehicle performance and reducing operational and maintenance costs.]]></description>
      <pubDate>Wed, 27 Aug 2008 14:09:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/869533</guid>
    </item>
    <item>
      <title>Summary of Dimensionless Texas Hyetographs and Distribution of Storm Depth Developed for Texas Department of Transportation Research Project 0-4194</title>
      <link>https://trid.trb.org/View/811169</link>
      <description><![CDATA[Hyetographs and storm depth distributions are important elements of hydraulic design by Texas Department of Transportation engineers. Design hyetographs are used in conjunction with unit hydrographs to obtain peak discharge and hydrograph shape for hydraulic design. Storm-depth distributions can be used to assess the probability of a total rainfall depth for a storm. A research project from 2000–2004 has been conducted to (1) determine if existing Natural Resources Conservation Service (NRCS) dimensionless hyetographs are representative of storms in Texas, (2) provide new procedures for dimensionless hyetograph estimation if the NRCS hyetographs are not representative, and (3) provide a procedure to estimate the distribution of storm depth for Texas. This report summarizes the research activities and results of the research project. The report documents several functional models of dimensionless hyetographs and provides curves and tabulated ordinates of empirical (nonfunctional) dimensionless hyetographs for a database of runoff-producing storms in Texas. The dimensionless hyetographs are compared to the NRCS dimensionless hyetographs. The distribution of storm depth is documented for seven values of minimum interevent time through dimensionless frequency curves and tables of mean storm depth for each county in Texas. Conclusions regarding application of the research results are included in the report.]]></description>
      <pubDate>Tue, 26 Jun 2007 14:32:25 GMT</pubDate>
      <guid>https://trid.trb.org/View/811169</guid>
    </item>
    <item>
      <title>Geomorphic, Aquatic, and Engineering Design Considerations for Low-Water Crossings</title>
      <link>https://trid.trb.org/View/810130</link>
      <description><![CDATA[A wide variety of low-water stream crossings have been built on low-volume roads across the United States over the past 50 years with the primary objectives of traffic access and cost savings. They are generally a rigid structure in a dynamic stream system, so most have worked to varying degrees from a road use standpoint. Many have required maintenance, repairs, or design modifications to function as they exist today. In addition, most structures have caused problems with regard to stream sediment transport, promoting upstream aggradation or downstream scour and creating barriers or limitations to the passage of aquatic organisms. Three fundamental types of fords both maintain good stream function and provide for traffic use: simple at-grade fords, low-water bridges, and vented fords with a large waterway opening area, preferably with a natural stream channel bottom. Each has a large waterway open area that does not constrict most flow. Ideally the width is at least equal to that of the natural bankfull channel. This paper discusses the problems observed and the requirements for a ford to meet stream function needs, pass sediment appropriately, provide for the passage of fish and other aquatic organisms, and meet engineering design needs. Some fords are designed specifically to function in extreme dynamic conditions, such as in debris torrent or alluvial fan channels, in desert or other “flashy” hydrologic regimes, or where debris jams and overbank flooding are frequent. Fitting the structure to the site requires experience and sound geomorphic, hydraulic, and engineering design. The task should be undertaken with an interdisciplinary team approach.]]></description>
      <pubDate>Thu, 07 Jun 2007 10:20:30 GMT</pubDate>
      <guid>https://trid.trb.org/View/810130</guid>
    </item>
    <item>
      <title>Hydraulic Design of Energy Dissipators for Culverts and Channels</title>
      <link>https://trid.trb.org/View/781657</link>
      <description><![CDATA[The purpose of this circular is to provide design information for analyzing dissipation problems at culvert outlets and in open channels.  The first five chapters of the circular provide general information to support the remaining design chapters.  These chapters discuss the design concept, erosion hazards, culvert outlet velocity and velocity modification, flow transitions, and estimating scour at culvert outlets.  Chapters 6 through 11 address hydraulic jump, forced hydraulic jump basins, Contra Costa energy dissipators, drop structures, stilling wells, and riprap basins.  The final chapter deals with design selection and presents examples of the application of each type of energy dissipator.  This manual should be considered a dynamic framework within which material will be added and deleted as new information becomes available.]]></description>
      <pubDate>Mon, 15 May 2006 15:14:38 GMT</pubDate>
      <guid>https://trid.trb.org/View/781657</guid>
    </item>
    <item>
      <title>A Better Design for Box Culverts?</title>
      <link>https://trid.trb.org/View/766994</link>
      <description><![CDATA[This article explores how the Federal Highway Administration (FHWA) and the South Dakota Department of Transportation (SDDOT) collaborated to study the affects of inlet geometry on water flow in cast-in-place and precast structures such as box culverts. The FHWA-SDDOT research project, "Effects of Inlet Geometry on Flow Capacity of Single and Multiple Barrel Box Culverts," examined the coefficients for straight and flared inlets. The researchers conducted nearly 700 tests at the Turner-Fairbank Highway Research Center (TFHRC) Hydraulics Laboratory. Among the results were that there is almost no gain to edge bevel shapes for unsubmerged inlet control flow since the top edge with the primary bevel is not exposed to the flow. The following are among the significant findings: (1) Based on the particle image velocimetry (PIV) flow visualization technique developed at the TFHRC laboratory, the researchers determined that the optimum edge treatment for the crown of a culvert is a rounded radius of 203 millimeters (8 inches). This is the full thickness of the crown for the models tested. (2) There was a distinct difference in performance between square-edged crowns, beveled crowns, and rounded crowns for box culvert models with straight wingwalls under submerged conditions. (3) Multiple barrels had a slight but negligible hydraulic advantage over single-opening culverts for the inlet tests. Researchers noted that highway agencies seldom design for headwater depths greater than 1.5 times the culvert height. (4) Wide span-to-rise models acted similarly to multiple barrels, except where there was a slight hydraulic disadvantage in the coefficients for the wide-span models compared to the 1:1 span-to-rise models for both the inlet control tests and the outlet control tests. (5) No hydraulic advantage or disadvantage to extending the inner walls of multiple-barrel culverts onto the apron were found. (6) Skewed headwalls were found to have a detrimental effect on culvert hydraulics. Data from this study will be incorporated into current hydraulic design software, and as such, box culvert designs should become more efficient and cost-effective soon.]]></description>
      <pubDate>Fri, 02 Dec 2005 11:18:20 GMT</pubDate>
      <guid>https://trid.trb.org/View/766994</guid>
    </item>
    <item>
      <title>Review of the Hydraulic Capacity of Bridges in a Coastal Area</title>
      <link>https://trid.trb.org/View/757309</link>
      <description><![CDATA[This technical note presents an analysis of the hydraulic capacity of several bridges in a coastal area in Mexico, following cyclonic floods. The heights and lengths of the bridges and the flow rates of the rivers were the comparison parameters used. The analysis showed that for floods occurring within a 100-year return period these bridges were insufficient in length and/or height. A comparative graph shows that the failed and nonfailed bridges are clearly separated by a tendency line and its equation was obtained. Without intending this equation to be taken as a universal rule, its application could be a useful point of departure in reviewing the design of bridges in coastal areas.]]></description>
      <pubDate>Wed, 06 Jul 2005 10:12:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/757309</guid>
    </item>
    <item>
      <title>HYDRAULIC DESIGN OF HIGHWAY CULVERTS, SECOND EDITION</title>
      <link>https://trid.trb.org/View/698061</link>
      <description><![CDATA[Hydraulic Design Series Number 5 combines culvert design information previously contained in Hydraulic Engineering Circulars (HECs) No. 5, No. 10, and No. 13 with hydrologic, storage routing, and special culvert design information.  The result is a comprehensive culvert design publication. Hydrologic analysis methods are described, and references cited. Culvert design methods are presented for both conventional culverts and culverts with inlet improvements.  Storage routing techniques are included which permit the designer to account for ponding effects upstream of the culvert.  Unique culvert applications, erosion and sediment control, debris control, structural aspects, and long-span culverts are discussed and references cited.  Inlet control, outlet control, and critical depth design charts, many of which are newly developed, are included for a variety of culvert sizes, shapes, and materials. New dimensionless culvert design charts are provided for the design of culverts lacking conventional design nomographs and charts.  The appendices of the publication contain the equations and methodology used to construct the design charts, information of the hydraulic resistance of culverts, and methods of optimizing culvert design using performance curves and inlet depression.  Calculation forms are provided for most of the design methodologies in the manual.  The second edition has corrected minor errors and provided both SI and English (U.S. customary) units for all equations and design charts.]]></description>
      <pubDate>Fri, 28 May 2004 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/698061</guid>
    </item>
    <item>
      <title>CULVERT DESIGN SYSTEM</title>
      <link>https://trid.trb.org/View/169700</link>
      <description><![CDATA[This system can be used to hydraulically design a culvert or hydraulically review an existing or proposed culvert size.  The design or review process for drainage culverts is accomplished by routing a hydrograph through the culvert, thereby taking advantage of temporary upstream pond storage. Analysis employing the irrigation design alternative uses only the peak discharge.  Various hydrograph relationships, culvert shapes, material, and inlet types can be investigated.  The system provides certain environmental and flood hazard data in addition to the culvert hydraulics. The system can be used in any geographical region provided discharges, hydrographs and flood volumes can be identified. Although not part of the system, these practices will aid in identifying any "safety factors" and related cost benefits associated with the culvert design.  The system consists of 39 computer programs for computations and plotting and an executive program which controls the flow of the user designated execution of the program segment.  All programs are written in FORTRAN IV with the exception of one assembler routine ("GEN4") used in plotting.  The plotting programs require either a Xynetics, Calcomp, or similar type of software plotting package.]]></description>
      <pubDate>Sun, 23 Nov 2003 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/169700</guid>
    </item>
    <item>
      <title>HYDRAULIC ANALYSIS OF BROKEN-BACK CULVERTS</title>
      <link>https://trid.trb.org/View/484227</link>
      <description><![CDATA[A broken-back culvert is defined as a culvert in which one or more breaks occur in the culvert profile.  An analysis model called Broken-Back Culvert Analysis Program (BCAP) was developed to evaluate the hydraulic performance of such culverts.  BCAP uses design inputs of discharge, culvert shape, size, material, and inlet type, culvert profile and tailwater conditions to predict the headwater depth, water surface profile and outlet velocity of a broken-back culvert.  Using this information, the user can determine if the culvert is operating satisfactorily or if it needs to be modified by either altering the culvert design or adding an energy dissipator to the culvert.  An important feature of BCAP is the ability to predict the occurrence, location, and length of hydraulic jumps inside broken-back culverts.  Model results compared favorably to those from tests completed in the Hydraulics Laboratory at the University of Nebraska-Lincoln and to compatible tests from the Federal Highway Administration computer program HY8.]]></description>
      <pubDate>Sun, 16 Jun 2002 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/484227</guid>
    </item>
    <item>
      <title>FORCES ON EDGE-HINGED PANELS IN GRADUALLY VARIED FLOW</title>
      <link>https://trid.trb.org/View/635907</link>
      <description><![CDATA[This paper describes a mathematical model leading to experimental analysis to estimate the hydraulic forces on a prototype edge-hinged panel (wicket gate) in gradually varied flow.  The two-dimensional potential theory of hydrodynamics is used to model the effect of the mean water flow approaching a gate aperture controlled by a hydraulic wicket in a locks-and-dam system.  The mean pressure against a typical wicket partially blocking the aperture is then modeled using conformal mapping. The elastic reaction at the supporting shaft of the gate is derived from equilibrium considerations.  The effect of the fluctuations of the pressure field about the mean is obtained through an application of the theory of stationary random processes.  The total design reaction at the shaft of the wicket is cast in a first-order second-moment format.  The theoretical model is compared with experiments on a 1/25-scale physical model.  The application of the model in hydraulic design of wicket gates is illustrated by means of a practical example.]]></description>
      <pubDate>Sun, 27 Sep 1998 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/635907</guid>
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