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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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      <link>https://trid.trb.org/</link>
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    <item>
      <title>The Rational Method, Regional Regression
Equations, and Site-Specific Flood-Frequency Relations</title>
      <link>https://trid.trb.org/View/1584751</link>
      <description><![CDATA[A study of 20 undeveloped watersheds with drainage areas from 1.26mi² to 124mi², watershed main channel length from 10,300ft to 175,000ft, and dimensionless main channel slope from 0.003 to 0.02, was undertaken to examine the relation between drainage area and appropriate technology for estimating watershed hydrologic response. The rational method, the existing set of regional regression equations, and two new sets of regional regression equations were applied to estimate 5-, 10-, 25-, 50-, and 100-year discharges. In addition, either the four-parameter kappa distribution or the generalized logistic distribution was fit to the annual series of maximum discharges for each watershed. The fitted distribution served as the basis for comparison of the other methods. Watershed area was not a discriminator for appropriate hydrologic method. The Kerby and Kirpich equations for time of concentration produced reasonable results, consistent with results reported in other work. Estimates of discharge using newly developed PRESS-minimized regression equations were subject to less bias than either the regression equations currently in use or the logarithm-transformed equations developed as part of this study. Additional work is required to extend results from the 20 study watersheds to a larger database, including watersheds subject to urbanization.]]></description>
      <pubDate>Thu, 28 Feb 2019 16:37:08 GMT</pubDate>
      <guid>https://trid.trb.org/View/1584751</guid>
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    <item>
      <title>Synthesis of TxDOT Storm Drain Design</title>
      <link>https://trid.trb.org/View/1584742</link>
      <description><![CDATA[The Texas Department of Transportation (TxDOT) currently uses the Rational method for development of design peak flow rates for its highway storm drainage design. Watersheds for which it is used have drainage areas less than 200 acres. The Rational method is an "instantaneous" peak discharge method that is popular due to its simplicity. The Rational method assumes a linear relation between rainfall rate for the time of concentration of the watershed and peak instantaneous discharge. The drawback of the Rational method, however, is that the time distribution and accumulation of flow cannot be precisely accounted for through each node (inlet) and run (conduit) of the system. Instead, the accumulated effects of all contributing sub-basins and branches are assumed to be “lumped” into a single equivalent basin when designing or analyzing each successive node or run. Use of peak discharge values also limits the hydraulic design and analysis of the system to the assumption of simple steady-state flow conditions. While this may result in a simple design process, the inability to consider unsteady flow and the inherent storage available in these systems may result in the missed opportunity to develop more cost-effective designs. Simple steady-state flow assumptions may also be inadequate to address the complex hydraulics that could be associated with the need to include non-traditional hydraulic features, such as in-line water quality basins. Therefore, the proposed study is intended to be the first phase in evaluating TxDOT procedures for storm drain design, not only in terms of the adequacy of current TxDOT practice relative to new directions in the field, but also in anticipation of the need to evaluate more complex features that might be required by changes in water quality regulations. The study is accomplished by completing two tasks: (1) a literature review to synthesize both the technical approach (Rational method versus other hydrological methods) and modeling efforts of drainage networks with various computer software packages, and (2) use of modeling tests on simple cases to examine storm drainage design.]]></description>
      <pubDate>Mon, 25 Feb 2019 11:46:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/1584742</guid>
    </item>
    <item>
      <title>Empirical Support for the Rational Method</title>
      <link>https://trid.trb.org/View/881252</link>
      <description><![CDATA[The Rational method is widely used in the design of hydraulic structures, such as storm sewers and culverts.  Many engineers consider the Rational formula a “rule-of-thumb” method and dismiss it in favor of regional flood frequency equations.  This paper presents analysis of 72 gaged watersheds in Kansas, ranging in size from 0.17 to 29.6 mi2, to provide empirical support for the Rational method.  It is shown that the Rational equation can be derived using regional flood frequency analysis.  The resulting Rational equation actually explains more of the variance in flood quantities than the standard form of the USGS regional flood frequency equations that are used in Kansas.]]></description>
      <pubDate>Mon, 16 Mar 2009 07:22:47 GMT</pubDate>
      <guid>https://trid.trb.org/View/881252</guid>
    </item>
    <item>
      <title>Don't Use an Elephant Gun to Shoot Flies</title>
      <link>https://trid.trb.org/View/837049</link>
      <description><![CDATA[There are many software engines for stormwater design and modeling.  This article discusses how to choose the best software modeling method to meet the scope of the particular need and application.  Stormwater modeling methods fall into one of three tiers:  the fully dynamic wave method, hydrologic routing and the rational method.  Dynamic methods such as the fully dynamic wave method are often the most accurate, but are very complex.  Hydrologic routing is a simplified method that still offers dynamic analysis but considers fewer factors.  Third tier models use steady state rational method hydrology and are not dynamic.   However, they can be the best choice for some jobs since they often provide the most conservative analysis.  In choosing the most appropriate method, consideration needs to be given to the audience, agency requirements, modeling choice of other designers and the skill level of the designer.]]></description>
      <pubDate>Mon, 22 Oct 2007 10:15:36 GMT</pubDate>
      <guid>https://trid.trb.org/View/837049</guid>
    </item>
    <item>
      <title>Storage Effects at Culverts</title>
      <link>https://trid.trb.org/View/775610</link>
      <description><![CDATA[Temporary ponding of water on the upstream side of a culvert serves to reduce the peak discharge that the culvert must convey.  In most cases the discharge reduction resulting from detention storage is minor and can be neglected in design.  However, in some cases the storage effect is substantial, and accounting for it may result in a more economical design.  This report presents new methods for quickly estimating the effects of detention storage on the performance of existing culverts and the sizing of new culverts.  These methods, which do not require hydrograph routing, are applicable to pipe and box culverts operating under inlet control with no overtopping of the roadway.  Peak discharges can be computed by the Rational method, USGS regression equations or any other appropriate method.  Water-surface areas at two or more stages are needed to define an approximate depth-area relationship.  The required areas can be estimated from existing topographic maps or measured in the field by one person with a rotating laser level and a Global Positioning System (GPS) unit.  Analyses of seven pipe-culvert sites in Johnson County showed that detention-storage design would reduce the required pipe diameter by at least one increment at five of the seven sites, and by two or more increments at three of the sites.  Similar analyses of ten box-culvert sites showed that detention-storage design would reduce the required span by more than 10% at three of the ten sites.  Our test results indicate that storage effects are less likely to be significant for large culverts than for small culverts.  The design of a culvert for detention storage rather than peak flow generally requires another survey, extra design effort and the purchase of additional right-of-way or drainage easement for the storage area.  Detention-storage design is economically justifiable only if cost savings on the culvert exceeds these added costs.  In locations where storage effects are significant but detention-storage design is not economically justifiable, the culvert should be designed for peak flow.]]></description>
      <pubDate>Thu, 02 Mar 2006 10:01:48 GMT</pubDate>
      <guid>https://trid.trb.org/View/775610</guid>
    </item>
    <item>
      <title>ROUTE CHOICE BEHAVIOR MODEL BASED ON BOUNDED RATIONALITY</title>
      <link>https://trid.trb.org/View/662061</link>
      <description><![CDATA[This paper proposes a sophisticated framework of a route choice behavior model. The model has an explicit relationship between the environmental properties drivers refer to and their route choice criteria. Two experiments about route choice behavior were performed:  (1) experimental subjects choose the routes on a map when the destination is unfamiliar; and (2) they choose and drive the routes when the destination is familiar.  A protocol analysis is used for classification of the environmental properties and the route choice criteria.]]></description>
      <pubDate>Thu, 10 Jul 2003 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/662061</guid>
    </item>
    <item>
      <title>BENDING STIFFNESS OF CONCRETE FLEXURAL MEMBERS REINFORCED WITH HIGH STRENGTH STEEL</title>
      <link>https://trid.trb.org/View/717712</link>
      <description><![CDATA[Reinforcing bars with a minimum yield strength of 500 MPa (72.5 ksi) are currently in use in Australia.  The paper examines the effect of this high strength reinforcement on the bending stiffness of flexural members.  The influence of tensile steel ratio, concrete strength and shrinkage of concrete on the bending stiffness is studied using a parametric analysis.  It is found that for the same service load the bending stiffness of members with 500 MPa (72.5 ksi) reinforcement varies between 85 and 100% of that of members reinforced with 400 MPa (60 ksi) steel depending on tensile steel ratio.  Also shrinkage of concrete should be included in the bending stiffness calculations for members with tensile steel ratio less than about 0.008.]]></description>
      <pubDate>Mon, 04 Feb 2002 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/717712</guid>
    </item>
    <item>
      <title>INFORMATION AND RATIONAL EXPECTATIONS IN MODELING DRIVER INFORMATION SYSTEMS: A WELFARE MEASUREMENT. IN: BEHAVIORAL AND NETWORK IMPACTS OF DRIVER INFORMATION SYSTEMS</title>
      <link>https://trid.trb.org/View/659751</link>
      <description><![CDATA[This paper presents an analytical framework to measure the economic values of information systems for route investigation. The welfare measurement is made by use of the random expected utility model with rational expectations.  The drivers' expectations can endogenously emerge in rational expectation equilibria.  The paper is organized as follows:  the REE model is formulated in Section 4.2; the framework to measure the economic benefit of information systems is present in Section 4.3; drivers' willingness-to-pay measures for information systems are formulated in Section 4.4; and we present numerical examples in Section 4.5.]]></description>
      <pubDate>Wed, 28 Jun 2000 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/659751</guid>
    </item>
    <item>
      <title>LONG LIVE THE RATIONAL METHOD</title>
      <link>https://trid.trb.org/View/639306</link>
      <description><![CDATA[Much of today's urban hydrology and hydraulics is carried out by designers with little hydrologic expertise.  The traditional rational method hydrograph is simple to construct, understand, and check.  The formula's simplicity is its strong suit:  you plug in acres and inches per hour on one side of an equation and render cubic feet per second on the other.  Civil engineers like it so much that they have created many varieties of rational method hydrograph recipes:  the modified rational, the universal rational, the Dekalb rational, and the Z-Rat.  However, one of the biggest problems in the civil engineering industry is the lack of a common methodology for urban hydrology.  Countless man-hours and millions of dollars are wasted each year on design issues revolving around differing hydrologic methods.  This article argues that these other creative recipes should be abandoned and the traditional rational method hydrograph embraced.  It maintains that its use as a standard will help eliminate the ongoing, multimethod confusion and waste that exists today, while adding much needed consistency to designs and harmony among civil engineers.]]></description>
      <pubDate>Tue, 08 Feb 2000 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/639306</guid>
    </item>
    <item>
      <title>TOWARDS A GOAL ORIENTED AND COMPREHENSIVE ROAD POLICY PROCESS</title>
      <link>https://trid.trb.org/View/538283</link>
      <description><![CDATA[The Norwegian Road and Road Transport Plan of 1998-2007 is meant to produce a parliamentary decision-making process based on definition of desired goals and the efficacy of measures available, a process more in line with the principles of rational planning.  In addition, the intention was to involve the Members of Parliament less in project details and more in discussions of policy framework.  This report reveals a less detail and project focused political process than before but still not characterized by the features of rational planning.  This is partly because the methodology used in the plan - namely the use of alternative road policy strategies - does not fit the political process too well, and partly due to political factors more related to the upcoming parliamentary elections.]]></description>
      <pubDate>Mon, 28 Dec 1998 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/538283</guid>
    </item>
    <item>
      <title>COMPUTING PEAK FLOW: WHICH METHOD IS MOST RATIONAL?</title>
      <link>https://trid.trb.org/View/458181</link>
      <description><![CDATA[Computing peak flow rates for small drainage areas is a routine task for civil engineers.  A peak flow rate may be needed to design a culvert, bridge, settling basin, or other drainage feature.  The most common methods used to determine peak flow rate are the rational method and the Soil Conservation Service (SCS) method.  This article discusses and compares these two methods and provides information on variations and refinements to the basic techniques.  The methods described are only appropriate for small drainage areas.]]></description>
      <pubDate>Mon, 11 Mar 1996 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/458181</guid>
    </item>
    <item>
      <title>CAN ROAD TRAFFIC LAW ENFORCEMENT PERMANENTLY REDUCE THE NUMBER OF ACCIDENTS?</title>
      <link>https://trid.trb.org/View/372204</link>
      <description><![CDATA[In this paper it is argued that conventional analyses of road user adaptation to traffic law enforcement, based on parametric rational-choice theory, are flawed.  Such analyses only consider road-user actions as a response to enforcement level and penalty size and do not simultaneously consider enforcement as a response to road-user behavior.  If each party is considered a rational agent who adapts to the other's behavior, the proper way to analyze the outcomes is by way of game theory.  A game theoretic model is presented and the main implications are: (i) most attempts at enforcing road traffic legislation will not have any lasting effects, either on road-user behavior or on accidents;  (ii) imposing stricter penalties (in the form of higher fines or longer prison sentences) will not affect road-user behavior; (iii) imposing stricter penalties will reduce the level of enforcement; (iv) implementing automatic traffic surveillance techniques and/or allocating enforcement resources according to change mechanism, and not according to police estimates of violation probability, can make enforcement effects last, but both alternatives are difficult to implement. Relevant empirical studies are reviewed, and they seem to support the conclusions arrived at by the game theoretical model.]]></description>
      <pubDate>Tue, 16 Feb 1993 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/372204</guid>
    </item>
    <item>
      <title>THE SASKATCHEWAN COMMON-FOR-HIRE CARRIER INDUSTRY: A RATIONALIZATION APPROACH</title>
      <link>https://trid.trb.org/View/66390</link>
      <description><![CDATA[The purpose of this paper is to describe the Saskatchewan portion of a national study to evaluate urban trucking rationalization techniques.  The objective of the study is to establish a methodology for the evaluation of truck rationalization and locally it is intended to evaluate the possibilities of applying various rationalizing techniques to problems in the local-for-hire trucking industry.]]></description>
      <pubDate>Mon, 27 Apr 1981 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/66390</guid>
    </item>
    <item>
      <title>RATIONAL METHOD FOR ESTIMATING CAMBER AND DEFLECTION OF PRECAST PRESTRESSED MEMBERS</title>
      <link>https://trid.trb.org/View/54169</link>
      <description><![CDATA[The author presents a step-by-step rational procedure for determining long-time multipliers for camber and deflection of precast prestressed concrete members.  Tables presented illustrate the sensitivity of the equations to various variables and show that except for extremely long members the variations are within the tolerances prescribed. Equations are provided for a more precise analysis.]]></description>
      <pubDate>Tue, 27 Dec 1977 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/54169</guid>
    </item>
    <item>
      <title>ALGORITHM 1: THREE-POINT RATIONAL FUNCTION INTERPOLATION FOR CALIBRATING GRAVITY MODELS</title>
      <link>https://trid.trb.org/View/53431</link>
      <description><![CDATA[The purpose of this subroutine is to calibrate singly or doubly constrained gravity models by adjusting the impedance parameter beta using a three-point rational function to ensure that the observed and model mean trip costs are within a prespecified level of accuracy. The procedure adopted is outlined with a brief discussion of the underlying theory. /TRRL/]]></description>
      <pubDate>Thu, 08 Dec 1977 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/53431</guid>
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