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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>MODELS AND APPLICATIONS. PROCEEDINGS OF SEMINAR F HELD AT THE 23RD EUROPEAN TRANSPORT FORUM, UNIVERSITY OF WARWICK, ENGLAND, SEPTEMBER 11-15, 1995. VOLUME P393</title>
      <link>https://trid.trb.org/View/463318</link>
      <description><![CDATA[Papers at this seminar presented the results of various model studies, and included discussion of land use transportation models, strategic models, value of time results, and issues related to the SACTRA report.  For abstracts of individual papers see IRRD 880169-880186.]]></description>
      <pubDate>Mon, 19 Aug 1996 00:00:00 GMT</pubDate>
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      <title>INFLUENCE OF TRAVEL TIME DISTRIBUTION ON SHORT TERM FORECASTINGS OF FREEWAY FLOWS</title>
      <link>https://trid.trb.org/View/462362</link>
      <description><![CDATA[An analysis has been carried out in order to study the distribution of travel times between on-off ramps and the speed distribution along road sections. The first relevant result is that a travel time distribution really exists which is very similar to some statistical distributions. The second result is that the parameters of the distribution depend on some independent variables such as: type of vehicle, features of the way, day, hour, length of road section, flow. In order to define the most reliable distribution of travel time to consider in forecasting models, a lot of studies have been carried out about these distributions by using statistical methods and filtering techniques. Then it is possible to predict the off-ramps flow according to the features of traffic and to the in-ramps flow which can be measured or predicted itself. A model has been developed in order to predict traffic flow in a point of the network based on these concepts. This model has been tested in the case of the Italian freeway A4 (Venezia-Trieste). This approach allows to consider a lot of partially unknown random variables by using the speed distribution obtained from historical and actual data, and to create a much more realistic forecasting model.  (A) For the covering abstract see IRRD 877041.]]></description>
      <pubDate>Fri, 28 Jun 1996 00:00:00 GMT</pubDate>
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      <title>AN INVESTIGATION OF AREA SPEED FLOW RELATIONSHIPS BY MICRO-SIMULATION</title>
      <link>https://trid.trb.org/View/462363</link>
      <description><![CDATA[Several recent strategic studies have used linear relationships between system speed (veh-km/veh-h) and veh-km to represent the demand-supply interaction. These "area speed-flow relationships" are based on empirical work in the 1970s, but there has been no detailed investigation of the way in which such relationships are generated, or how they are affected by the nature of the network or the pattern of demand. This paper discusses the background to the problem, and presents results of an EPSRC funded study which is investigating the interaction between system speed and vehicle kilometres in different types of network. Four relationships are being obtained, between (i) speed (veh-km/veh-h) and actual flow (veh-km/h), (ii) speed (veh-km/veh-h) and demanded flow (veh-km/h), (iii) time/km (veh-h/veh-km). The data is collected directly from the micro-simulation package NEMIS for an origin-destination matrix which is factored to represent different levels of demand. The modelling and data collection methodology is described and results for various networks presented. The implications of these results are discussed in terms of definition of network capacity and in implications for strategic modelling and evaluation.  (A)  For the covering abstract see IRRD 877041.]]></description>
      <pubDate>Fri, 28 Jun 1996 00:00:00 GMT</pubDate>
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      <title>TEMPORAL VARIATIONS ON SPEED FLOW RELATIONSHIP OF GERMAN MOTORWAYS</title>
      <link>https://trid.trb.org/View/462364</link>
      <description><![CDATA[The dependence of the speed-flow relationship on the traffic volume has been discussed time and time again over the last years. Traffic demand varies systematically and can be explained by daily, weekly, and yearly cycles of traffic volume. The speed behaviour is also subject to temporal variations. These variations do not only depend on the traffic volume, but they also can be attributed to the different desired speed of the drivers. Furthermore the environment conditions (daylight and weather) have considerable influences on the speed behaviour. These temporal variations could be even stronger than the dependence of the speed on the traffic volume. The aim of the research project is to point out the differences of capacity between the sorts of days (weekday, weekend, holidays) and between the varying environmental conditions. Furthermore the basic relationships of the systematic variations towards the capacity are shown, noticed from the daily and yearly cycles. The database of the project was built by measurements of 15 continuous counting machines at two and three lane carriageways. These measurements were done over a time of three years (1991-1993). The effects of different sorts of days on the speed-flow relationship are not of a uniform nature. They vary on the different counting points. The influence of the environment conditions are shown by comparison of the speed-flow diagrams, with the permutations light/dark and dry/wet. By the analysis of the measured time-series the general trends of the velocity and traffic volume development are shown. It is also shown that at the same environmental conditions higher velocities are observed in winter than in summer. (A)  For the covering abstract see IRRD 877041.]]></description>
      <pubDate>Fri, 28 Jun 1996 00:00:00 GMT</pubDate>
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      <title>THE INFLUENCE OF MODELLING ERROR ON THE SHAPES OF ESTIMATED DEMAND FUNCTIONS</title>
      <link>https://trid.trb.org/View/462365</link>
      <description><![CDATA[When we fit statistical demand functions to data about individuals, we are limited by the degree of modelling error present. Such modelling error might derive, for example, from day to day variation in individual behaviour, variation in behaviour over the population, fallibility in respondents' memories when answering our questions and the simplification involved when we concentrate only on the main influences on quantity demanded, in particular price. This paper reports on theoretical analysis of situations where modelling error has had undesirable results. One example to be considered is the often noted finding of asymmetric response, for example when asking travellers how they would react to improvements as against worsenments of service quality, or fare increases as against fare decreases. In Contingent Valuations Methodology this even has its own terminology - 'Willingness to Pay' and against 'Willingness to Accept'. This paper argues that too little attention is paid to the influence of modelling errors on these findings. A second example studied is from the area of consumer surplus calculations in transport models. Here the demand functions for new modes might be adequately estimated for the purpose of demand modelling, but not for the purpose of consumer surplus estimation, where the quantity demand at very high price is very critical to the calculation, but which is very poorly estimated by logit models.  (A)  For the covering abstract see IRRD 877041.]]></description>
      <pubDate>Fri, 28 Jun 1996 00:00:00 GMT</pubDate>
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      <title>STATED PREFERENCE TECHNIQUES AND THE REPRESENTATION OF ATTRIBUTES</title>
      <link>https://trid.trb.org/View/462366</link>
      <description><![CDATA[Stated Preference techniques are becoming increasingly popular within the fields of transport planning and management as a means of deriving monetary values which both users and non-users place on the attributes of transport systems. These often include tangible costs and benefits which can be represented to respondents easily in numerical terms (e.g. journey time, travel cost, frequency of service, etc.). There are however other attributes which cannot be expressed and comprehended so easily. Examples are journey time reliability, ride quality of a rail system, and environmental costs and benefits. This paper examines the sensitivity of the results of Stated Preference experiments as to how these types of attributes are represented to the respondent. Empirical evidence is drawn from a study into the estimation of demand for the Manchester LRT system, and which shows that the form and type of representation does have a significant influence on the outcome of Stated Preference research. The paper also examines the possible reasons for these differences particularly with respect to textual representation of attributes as opposed to those shown pictorially.  (A)  For the covering abstract see IRRD 877041.]]></description>
      <pubDate>Fri, 28 Jun 1996 00:00:00 GMT</pubDate>
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      <title>STATED PREFERENCE: TOO MUCH DEFERENCE?</title>
      <link>https://trid.trb.org/View/462367</link>
      <description><![CDATA[The way in which Stated Preference (SP) is designed and analysed is based on certain assumptions about how people behave. However, a growing body of research by psychologists and decision researches suggests that these assumptions may be inadequate. For example, it has been shown repeatedly that the same change in a service attribute is valued differently if presented as a gain or a loss, in fact a loss may be valued twice as highly as a gain. The additive compensatory model so often assumed seems to be a poor model of how people actually make choices, since in practice they use a mixture of methods. Furthermore, SP assumes people have full information, in practice they often only seek partial information. This paper addresses how this research may be used to improve the practice of SP. It begins with a brief review of some of the more significant findings of researchers in non transport disciplines, and considers how this research impacts on the practice of SP in transport, and what changes should be adopted. The recommendations are backed up by practical results from our own fieldwork. Comparative analyses of mode choice SP data are presented to illustrate the effect of differing weights for gains and losses. The way in which presentation of full information affects choices previously made on imperfect knowledge is assessed based on a study in the field in early 1995. (A)  For the covering abstract see IRRD 877041.]]></description>
      <pubDate>Fri, 28 Jun 1996 00:00:00 GMT</pubDate>
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      <title>AN ANALYSIS OF NON-RESPONSE IN TRAVEL DIARY SURVEYS</title>
      <link>https://trid.trb.org/View/462368</link>
      <description><![CDATA[The aim of this paper is to report the results of an analysis of non-response, using what is believed to be a unique dataset collected in the context of the VITAL project undertaken by the Transport Research Centre at the University of Melbourne. This dataset consists of information collected in a validation survey in which intensive in-depth interviews were undertaken with both the respondents and the non-respondents who had taken part in a more conventional mailout/mailback survey. This dataset permits a systematic identification of the factors influencing both the magnitude and character of unit and item non-response. The first section in the paper discusses, within a general framework, the problem of non-response and briefly reviews the existing evidence from the transport literature and elsewhere. The second section goes on to describe a modelling system which allows the joint investigation of unit and item non-response, including the investigation of survey administration factors such as the number of reminders sent to potential respondents. The third section briefly describes the VITAL dataset which consists of in-depth interviews conducted with almost 700 initial respondents. The fourth section presents the results of the analysis of non-response and discusses their significance in the context of current survey practice. The final section presents some overall conclusions from the work and on the basis of these conclusions, highlights a number of important directions for future methodological research.  (A)  An abstract only is published in the seminar proceedings.  For the covering abstract see IRRD 877041.]]></description>
      <pubDate>Fri, 28 Jun 1996 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/462368</guid>
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      <title>CONVERGENCE MONITORING FOR CONGESTED ASSIGNMENT IN ROAD SCHEME APPRAISAL</title>
      <link>https://trid.trb.org/View/462369</link>
      <description><![CDATA[A Department of Transport funded research project has investigated theoretical and practical approaches to convergence monitoring in the context of highway scheme appraisals. The aim of the project was to provide practitioners with guidance on which convergence measures to use to examine convergence, which stop criteria to aim for, and how to deal with cases on non-convergence or with any remaining uncertainty in the flow and associated delay forecasts. The research included a survey amongst practitioners and model developers, and multiple model applications using actual scheme appraisals and three commercial UK packages (CONTRAM, SATURN and TRIPS). The paper reports on the main research findings and proposes an appropriate approach to monitor convergence in practical applications. A two-stage procedure is recommended: (1) the first step seeks a satisfactory level of convergence of each individual assignment model, by meeting pre-specified criteria (this step applies to all applications of assignment); (2) the second step handles the remaining model uncertainty in terms of overall model outcomes (and is particularly applicable in highway scheme appraisal).  (A)  For the covering abstract see IRRD 877041.]]></description>
      <pubDate>Fri, 28 Jun 1996 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/462369</guid>
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      <title>THE ATTRACTIONS OF SUE - A PRACTICABLE APPROACH TO STOCHASTIC USER EQUILIBRIUM ASSIGNMENT</title>
      <link>https://trid.trb.org/View/462370</link>
      <description><![CDATA[Whilst User Equilibrium (UE) assignment methods have been applied with success to congested urban networks, and pure stochastic methods to lightly congested inter-urban networks, both have their weaknesses. UE methods are deterministic and assume that drivers have perfect and complete knowledge of network conditions and that all drivers perceive these conditions identically. Stochastic methods, on the other hand, allow for variations in knowledge and perceptions between drivers, but do not incorporate capacity restraint. Stochastic User Equilibrium (SUE) has for some time been a recognised goal. This paper describes a new SUE method, formed by incorporating capacity restraint (in the form of link-based cost-flow functions) into a stochastic loading method, which is profit-based (unlike dial) and numerical (unlike the Monte Carlo method of Burrell). The nature of the SUE algorithm is similar to the Frank-Wolfe method which is commonly used for the solution of the UE problem. A technique is described for overcoming the "deadlock" problem, thus permitting the method to be applied to networks of any configuration. The new model is demonstrated by applying it to the Sioux Falls network. The progress of the iterative process is shown by (1) the steady reduction in an objective function and (2) by a convergence statistic which measures the "distance" between the current and auxiliary solutions. It is shown how, as the variability parameter (representing the between-driver variation in perceptions of link cost) decreases, so the SUE solutions tend to the UE solution. Finally, the paper discusses possible extensions of the model to allow for multiple user classes, elastic demand and junction modelling.  (A)  For the covering abstract see IRRD 877041.]]></description>
      <pubDate>Fri, 28 Jun 1996 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/462370</guid>
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    <item>
      <title>THE PRACTICE OF A DUAL CRITERIA ASSIGNMENT MODEL WITH A CONTINUOUSLY DISTRIBUTED VALUE-OF-TIME</title>
      <link>https://trid.trb.org/View/462371</link>
      <description><![CDATA[An efficient path-storing equilibration algorithm is presented to solve a dual criteria assignment model with continuously distributed values of time. Applications include a sensitivity analysis and propagation of errors. A traffic assignment model is of particular interest to assess the traffic of a motorway project; it usually rests on the assumption that every trip-maker tries to minimize their generalized travel times, evaluated with respect to a uniform cost function. A dual criteria model enables an analyst to represent disaggregate trade-offs between two cost criteria, e.g. time and price in the cost vs time model. A fixed-times dual criteria model was first introduced to address the competition between the train and the plane in inter-regional transport (March, 1973). Then a mathematical formulation was designed to address both flow-dependent travel times and the elasticity of demand (Leurent, 1993a, 1993b). This paper includes two contributions to the practice of dual criteria assignment. First, a path-identifying algorithm is presented, wherein a generalized impedance is equalised between available paths: it is shown, based on a medium-size application (104 OD zones and 2,000 links) on a PC micro-computer, that this algorithm compares very favourably to the conventional, Frank-Wolfe procedure applied to the uniform, single value-of-time model of Wardrop and Beckmann. Second, a sensitivity analysis is worked out, in order to address issues like the uncertainty about the predicted revenue of a tolled urban motorway, due to the uncertainty about the distribution of the value-of-time across the trip-makers.  (A)  For the covering abstract see IRRD 877041.]]></description>
      <pubDate>Fri, 28 Jun 1996 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/462371</guid>
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    <item>
      <title>DISTRIBUTABLE TIME-DEPENDENT TRAFFIC ASSIGNMENT</title>
      <link>https://trid.trb.org/View/462372</link>
      <description><![CDATA[CONTRAM 5 finds wide application in scheme assessment and research as the only traffic assignment model producing (approximately) dynamic user equilibrium (DUE) loadings. It achieves this by assigning a stream of small flow packets to minimum cost routes, taking into account traffic interactions and anticipated network conditions. Any capacity or delay function may be used, so realism is not sacrificed to mathematical convenience. However, convergence is difficult to define, and scope for parallel or distributed computing is limited. CONTRAM 6 overcomes this by assigning time-dependent origin-destination movements independently and adjusting "splitting rates" to alternative routes (the first known practical implementation of this method). It drops fixed-column data for more flexible space-delimited relational format, better suited to graphics and model integration, with fewer restrictions on network size and value ranges. It updates networks only after assigning all o-ds, unlike CONTRAM 5 which updates after each packet, so initially large fluctuations in loading can occur. To control convergence, each o-d effectively has its own "step length", adjusted according to how path costs change. Relative duality gap (DUE "error") and total journey time are displayed graphically as the program runs. Typically, convergence to a few percent gap needs 15-30 iterations. After 30 iterations, 15 of 16 networks tested (up to 1663 links) produce a gap of 3% or less. Total journey times and other results are similar to CONTRAM 5. Run times are comparable with CONTRAM 5, but the inherently parallel, scalable logic of CONTRAM 6 offers the prospect of substantially reduced run times using parallel or distributed computation.  (A)  For the covering abstract see IRRD 877041.]]></description>
      <pubDate>Fri, 28 Jun 1996 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/462372</guid>
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    <item>
      <title>DRACULA: DYNAMIC ROUTE ASSIGNMENT COMBINING USER LEARNING AND MICRO-SIMULATION</title>
      <link>https://trid.trb.org/View/462373</link>
      <description><![CDATA[This paper describes DRACULA, a new kind of urban traffic assignment model under EPSRC-funded development since mid-1993. The major difference from conventional approaches is that DRACULA models the day to day evolution of traffic conditions, rather than some abstract long-term equilibrium state. Drivers respond to congestion through a learning sub-model, and daily select routes and departure times using a behavioural choice sub-model. A demand sub-model represents day-to-day variability in the network capacities (e.g. due to accidents). Finally, a traffic sub-model is used to move vehicles through the network on each day. Various forms and levels of detail of these sub-models may be selected by the user. At its most detailed level, DRACULA represents (i) the choices and experiences of individual drivers, and (ii) the movement of individual vehicles through the network ("microsimulation"), as these evolve in real-time and from day-to-day. The linking, for the first time, of such a detailed traffic model with an assignment capability has particularly important applications in the modelling of responsive signals (e.g. SCOOT) and environmental outputs, such as exhaust emissions. The application of DRACULA in an EC-funded study of driver information systems is presented as an example.  (A)  For the covering abstract see IRRD 877041.]]></description>
      <pubDate>Fri, 28 Jun 1996 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/462373</guid>
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    <item>
      <title>A NEW DYNAMIC MICRO-SIMULATION/ASSIGNMENT MODEL AND NEW ESTIMATES OF TRAFFIC CONTROL SYSTEM PERFORMANCE INCLUDING BUS PRIORITY EFFECTS</title>
      <link>https://trid.trb.org/View/462374</link>
      <description><![CDATA[The paper has two main sections. The first section of the paper describes a new micro-simulation model of urban traffic in which drivers tend to swap towards a better route and a better transport mode. The second section illustrates the utility of the model by applying it to assess two alternative bus priority schemes at signalised junctions in the City of York. The first of these two alternatives tends to grant an absolute priority to any approaching bus, by retaining the green indication until the bus has exited the approach, while the other alternative operates similarly but according to a specified set of maximum and minimum green timings. Results comparing both methods, against each other, and comparing each to a non-bus-priority system are given. Finally, some initial tentative results for road pricing and traffic control are given for the York network.  (A)  For the covering abstract see IRRD 877041.]]></description>
      <pubDate>Fri, 28 Jun 1996 00:00:00 GMT</pubDate>
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      <title>VISEM: TRAFFIC DEMAND CALCULATIONS BASED ON ACTIVITY CHAINS - MODELLING TECHNIQUES AND PRACTICAL USE WITHIN A TRANSPORTATION PLANNING SYSTEM</title>
      <link>https://trid.trb.org/View/462375</link>
      <description><![CDATA[Though the shortcomings of the four-step modelling process in transportation planning are obvious, most transportation planning systems in practical use are based on it. However, advanced disaggregate models are known to estimate and forecast trip-tables. VISEM, a planning system used in various cities throughout Europe and Asia, applies these sophisticated models. Comments on the methods and the data modelling reflecting the planning objective and the available data are made. The experience gained in a variety of land-use studies is presented to demonstrate the range of applications already carried out. VISEM simulates activities, trip chains are computed as a result. Although important dependencies within the trip-chains are covered, the system does not require extensive computing power due to aggregation of individuals to behavioural homogeneous groups. The models are calibrated and validated with the help of disaggregated survey data as well as aggregated census data. Revealed and stated preferences can be adopted within the models. The models are strongly tied to an urban and regional transportation planning system with the final objective to estimate mode specific traffic volumes in a more realistic manner than it is presently done using conventional four steps.  (A)  For the covering abstract see IRRD 877041.]]></description>
      <pubDate>Fri, 28 Jun 1996 00:00:00 GMT</pubDate>
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