<rss version="2.0" xmlns:atom="https://www.w3.org/2005/Atom">
  <channel>
    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
    <description></description>
    <language>en-us</language>
    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
      <url>https://trid.trb.org/Images/PageHeader-wTitle.jpg</url>
      <link>https://trid.trb.org/</link>
    </image>
    <item>
      <title>Efficacy of decentralized traffic signal controllers on stabilizing heterogeneous urban grid network</title>
      <link>https://trid.trb.org/View/2478383</link>
      <description><![CDATA[Macroscopic Fundamental Diagrams (MFDs) are valuable for designing and evaluating network-wide traffic management schemes. Since obtaining empirical MFDs can be expensive, analytical methodologies are crucial to estimate variations in MFD shapes under different control strategies and predict their efficacy in mitigating congestion. Analyses of urban grid networks' abstractions can provide an inexpensive methodology to obtain a qualitative understanding of impacts of control policies. However, existing abstractions are valid only for simple intersection layouts with unidirectional and single-lane links and two conflicting movement groups. Naturally, the real intersections are more complex, with multiple incoming and outgoing lanes, heterogeneous incoming links' capacities and several conflicting movement groups. To this end, the authors consider a grid network with differences in capacities of horizontal and vertical directions, allowing us to investigate the characteristics of control policies that can avoid pernicious gridlock in heterogeneous networks. The authors develop a new, more comprehensive network abstraction of such grid networks to analyze and compare the impacts of two families of decentralized Traffic Signal Controllers (TSCs) on the network's stability. The obtained theoretical insights are verified using microsimulation results of grid networks with multiple signalized intersections. The analyses suggest that considering both upstream and downstream congestion information in deciding signal plans can encourage more evenly distributed traffic in the network, making them more robust and effective at all congestion levels. The study provides a framework to understand general expectations from decentralized control policies when network inhomogeneity arises due to variations in incoming link capacities and turning directions.]]></description>
      <pubDate>Mon, 27 Jan 2025 15:39:52 GMT</pubDate>
      <guid>https://trid.trb.org/View/2478383</guid>
    </item>
    <item>
      <title>Safety Impact Factor Analysis at Intersections with Left-Turn Waiting Areas Based on Ordered Logit Model</title>
      <link>https://trid.trb.org/View/2000926</link>
      <description><![CDATA[In recent years, many cities have set up the left-turn waiting areas (LWA) at intersections. It not only improved the operation efficiency of intersections but also have impacted traffic safety performance. This paper focused on the characteristics of traffic conflicts at intersections with LWA and analyzed various factors affecting safety performance of LWA. The traffic conflict severity and traffic conflict frequency were used to identify the safety performance of intersections. The ordered logit model was built to find out the factors which have significant impacts on traffic safety at intersections with LWA. Results showed that the capacities of LWA, secondary conflicts, rear-end conflicts, confluence conflicts, clearance between vehicles, the left-turn traffic volumes, the numbers of receiving lanes, turning left in advance, and the types of left-turn phase have significant impacts on intersection safety with LWA. Finally, some management recommendations are put forward to improve the safety.]]></description>
      <pubDate>Tue, 15 Aug 2023 09:00:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/2000926</guid>
    </item>
    <item>
      <title>An Evaluation of the 1965 Highway Capacity Manual Method of Computing Intersection Capacities</title>
      <link>https://trid.trb.org/View/1690997</link>
      <description><![CDATA[The objectives of this study were to determine the range of errors resulting from use of the 1965 Highway Capacity Manual for estimating service volumes at signalized intersections in Missouri, to determine if the errors could be correlated to any particular characteristics of the intersection and if possible to develop procedures for adjusting the estimates of service volume. Complete traffic data was collected for 90 approaches to 53 intersections in the St. Louis, Kansas City and Springfield areas. The theoretical service volume was computed for each approach and was compared with the measured volume. The comparisons were expressed in terms of percent error between computed values and field measurements. Estimates of service volume for service levels A, B and C were found to be high and generally inaccurate. At level D estimates were more accurate, becoming acceptable as the load factor increased. At level E (capacity) the estimates were within acceptable limits and on the average were low. Average lane width and city were found to be correlated with the error between actual and computed values.]]></description>
      <pubDate>Fri, 20 Mar 2020 16:26:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/1690997</guid>
    </item>
    <item>
      <title>Performance evaluation of the inside intersection median-turn lane markings on the mobility and safety performance of signalized intersections in the Philippines and Japan</title>
      <link>https://trid.trb.org/View/1578031</link>
      <description><![CDATA[Signalized intersections are one of the key elements that play a vital role at road networks. The efficiency and safety levels of intersections can affect the operational performance of the whole system. In general, turning traffic, especially median-turning, has always been considered as the most problematic movement in the operation of intersections. This becomes more critical with high turning demand where exclusive turning lanes (single or double) can be assigned to provide larger capacities for these movements and to reduce conflicts with through traffic. However, improper treatment of median-turn lanes could create cross-maneuvering behavior which may limit the expected increase in capacity and create safety issues. Median-turning lane markings are commonly provided at intersections in Japan to guide drivers while turning which is expected to reduce the conflicts among turning traffic. Meanwhile, in the Philippines, exclusive median-turn lanes are installed at intersections without proper treatment which may contribute to the low mobility and safety levels. Therefore, this study evaluated the impact of inside intersection lane markings on the operation of median-turn lanes in terms of mobility and safety. The vehicle maneuver, speed and interactions between the turning traffic were utilized as essential components for the assessment. The empirical analysis shows that conflicting trajectories were present on double turn lanes without median-turn lane markings in the Philippines, which resulted to serious conflicts among the turning vehicles and negatively influenced the turning speed and saturation flow rate of the turn lanes. On the other hand, the turn lane markings in Japan, provided a positive impact to mobility and safety of the turning lanes. Moreover, it was also found that the geometric characteristics and traffic signal phasing scheme highly affects the capacity and safety condition of signalized intersections.]]></description>
      <pubDate>Thu, 21 Feb 2019 09:56:01 GMT</pubDate>
      <guid>https://trid.trb.org/View/1578031</guid>
    </item>
    <item>
      <title>Safety and Operations Guidance for Using Time-of-Day Protected-Permissive Left-Turn Phasing Using Flashing Yellow Arrows</title>
      <link>https://trid.trb.org/View/1571746</link>
      <description><![CDATA[Selection of the left-turn phasing mode is a significant decision for the safe and efficient movement of left-turning traffic at signalized intersections. Because of different safety and operational effects associated with the signal left-turn mode, the two must be evaluated concurrently and be balanced based on capacity and crash potential when protected-only, permissive-only, and protected-permissive left-turn (PPLT) phasing modes are compared. The choice between left-turn phasing modes can be made on a time-of-day basis so that changing traffic conditions are accommodated appropriately. The purpose of this study was to define guidance that field traffic engineers can use to select the appropriate left-turn mode based on prevailing traffic conditions by time of day. In particular, guidance on the use of PPLT or permissive-only with flashing yellow arrows (FYAs) to indicate permissive movements was of interest to the Virginia Department of Transportation (VDOT). Prior to the development of time-of-day guidance, the overall safety effects of converting between left-turn phase modes and indications (or displays) needed to be explored. The study examined the impact of converting from a circular “green ball” display for the permissive portion of PPLT phasing to the FYA signal indication and converting from protected-only phasing to PPLT with FYA. To quantify these conversions, a before-after evaluation of signal conversions was performed using standard Bayesian methods to develop crash modification factors from field data for 28 intersections in Virginia. For these intersections, the expected crash reduction after conversion from PPLT to PPLT-FYA was estimated as 12 percent (total crashes), 14 percent (fatal and injury crashes), and 30 percent (angle crashes), which was consistent with results from previous studies. In evaluating different left-turn phasing modes on a time-of-day basis, crash risk, left-turn conflicts, and capacity prediction models for permissive-only and PPLT modes were developed using simulation data. A total of 750 unique scenarios based on different combinations of intersection characteristics, traffic signal parameters, and traffic volumes were simulated in VISSIM, and trajectory files were processed using Surrogate Safety Assessment Model software to determine the number of conflicts per scenario. Based on the outputs of the simulation models, prediction models for determining left-turn capacities and the expected number of left-turn conflicts per hour per 100 left-turning vehicles were created using multiple linear regression. A final model predicting the average crash risk per hour based on the predicted number of conflicts was developed. The three models created were incorporated into a single spreadsheet tool that can be used by VDOT engineers in determining phasing mode on a time-of-day basis.]]></description>
      <pubDate>Sun, 16 Dec 2018 23:13:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/1571746</guid>
    </item>
    <item>
      <title>Identification of At-Grade Intersections Characteristics for Defining Basic Inputs into MCA Methodology</title>
      <link>https://trid.trb.org/View/1373291</link>
      <description><![CDATA[The article deals with the determination of basic traffic engineering and measurable urban planning criteria needed for a complex assessment of intersections. The current assessment method of intersections in accordance with applicable regulations is virtually bound on suitable capacities but each intersection may also be described by means of a set of clearly expressed values; based on these values, its suitability for given conditions and thus also the utility value of a proposed design solution may be determined by means of the Multi-Criteria Assessment (MCA) application. The basic criteria defining each at-grade intersection were the mean delay time, the safety index, environmental impacts (particularly CO₂, NOₓ and PM), noise impacts on the surroundings, construction and operating costs. In this context, it is obvious that it is also necessary to define the input parameters of a respective intersection on the basis of which the above values of the criteria will be defined. The article primarily describes the dependences between the above criteria and input traffic volumes for basic shapes of intersections. In the first phase, basic layout types of intersections were modelled in the form of a set of basic shapes of intersections – in the future, the authors plan to extend this set by multi-lane intersections and intersections with separate turn lanes. The distribution of traffic volumes into individual branches was carried out for several basic combinations. The dependences are elaborated in a clear graphical and tabular form allowing the designer or investor to make a preliminary assessment of different design options of an intersection, particularly in the initial phases of design. It is also possible to use the dependences as an alternative to computerised assessment in accordance with applicable regulations.]]></description>
      <pubDate>Tue, 24 Nov 2015 09:27:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/1373291</guid>
    </item>
    <item>
      <title>The Roundabout Capacity Estimate Microsimulation Model</title>
      <link>https://trid.trb.org/View/1355826</link>
      <description><![CDATA[Computer programs designed for traffic microsimulation have gained considerable popularity and widespread use, both in practical application as well as in research works. The number of traffic simulation models has increased significantly and until the end of the last century there were more then 50 simulation models available already. Their advantage is the ability to predict behavior in everyday traffic, as well as in emergency situations. Unlike conventional analytical methods for traffic analysis, simulation models can also display the dynamics of traffic systems and 2D or 3D animations, as a result of their modeling, are much more understandable to incompetent population. The aim of this paper is to briefly describe the basic settings of microsimulation computer programs. The AIMSUN computer program will be described in details and the process of making the AIMSUN (Advanced Interactive Microscopic Simulator for Urban and Non-Urban Networks) microsimulation model for roundabout in Radnička Street in Rijeka will be shown. Since the traffic simulation computer programs are commonly used to estimate characteristics of traffic flow, such as the average travel time, the capacity of roads or the average speed of vehicles, models are based on adjusting the input parameters in order to reach a reasonable matching between model results and field data. This process is called calibration, and it is necessary in proving the authenticity of the simulation model and model validation. For the calibration and validation of the planned simulation model in this case, the obtained results were compared with those obtained by another analytical capacity method (Austrian method) and the SIDRA INTERSECTION (Signalized & Unsignalized Intersection Design and Research Aid) computer program which is based on the Australian calculation method for roundabout capacities.]]></description>
      <pubDate>Mon, 01 Jun 2015 13:39:51 GMT</pubDate>
      <guid>https://trid.trb.org/View/1355826</guid>
    </item>
    <item>
      <title>Offset effects on the capacity of paired signalised intersections during oversaturated conditions</title>
      <link>https://trid.trb.org/View/1309842</link>
      <description><![CDATA[Paired signalised intersections (PSI) are two closely signalised intersections with short distance between them as queue spillbacks and upstream intersection blockages occur. Due to queue spillbacks, the PSI have their own consideration regarding operational characteristics that are different from isolated intersections or coordinated networks. This paper explores the effects of timing plans offset on the movement capacity that passes through both intersections under several cases and situations. For this purpose, an analytical model is chosen to evaluate the movement capacities. The model has been coded and integrated into INBAR software, then it has been validated with results from the micro simulation software Vissim for various tests. A comparison of the two sets of results shows only minor deviations. The importance of offset is demonstrated through sensitivity analyses for different timing plan variables and parameters.]]></description>
      <pubDate>Thu, 29 May 2014 10:15:31 GMT</pubDate>
      <guid>https://trid.trb.org/View/1309842</guid>
    </item>
    <item>
      <title>Traffic Characteristics and Intersection Capacities II. Intersection Capacity</title>
      <link>https://trid.trb.org/View/1278693</link>
      <description><![CDATA[Presentations at the Highway Research Board's 41st Annual Meeting, January 8-12, 1962.]]></description>
      <pubDate>Sat, 30 Nov 2013 09:27:08 GMT</pubDate>
      <guid>https://trid.trb.org/View/1278693</guid>
    </item>
    <item>
      <title>Australian road capacity guide: provisional introduction and signalized intersections</title>
      <link>https://trid.trb.org/View/1210134</link>
      <description><![CDATA[Methods are given for estimating the capacities and operating characteristics of signalized intersections.  Saturation flows, that is the rates at which vehicles can cross the stopline during the period that a green signal is showing, are calculated in terms of the number and types of lanes. Saturation flows are expressed in terms of through car units per hour of green.  Adjustments are given for kerb lane usage, lane width, gradient, parking and the effect of trams.  The y value for any approach or movement is the ratio of the arrival flow to the saturation flow for that approach or movement.  It is recommended that the sum of y values for an intersection should not exceed 0.7, Where the sum of y values must contain one and only one y value for each phase in the cycle.  Numerical examples are given to illustrate each type of calculation.  A method of measuring saturation flows is described in Appendix A.  This guide was reprinted in February 1978 as signalised intersections: capacity guide, Australian Road Research Board research report ARR 79, which was, in turn, superseded in March 1981 by traffic signals: capacity and timing analysis, Australian Road Research Board Research Report ARR 123.]]></description>
      <pubDate>Sat, 25 Aug 2012 00:06:54 GMT</pubDate>
      <guid>https://trid.trb.org/View/1210134</guid>
    </item>
    <item>
      <title>Design and analysis of roundabouts</title>
      <link>https://trid.trb.org/View/1209995</link>
      <description><![CDATA[The authors note that Victorian roundabouts have been operating under a priority rule for many years, that is entering drivers give way to circulating drivers.  This paper demonstrates that for Australian roundabouts (or at least Victorian roundabouts) capacity can be suitably estimated using a gap acceptance theory; they need not be large to achieve high capacities; they generally have operating characteristics superior to conventional alternatives; and their geometry should be devised to assist the driver performing the gap acceptance task.  The paper contains suggestions relating to layout, and line marking and details the capacity analysis of two roundabout designs which are superior to signalised intersection alternatives.]]></description>
      <pubDate>Sat, 25 Aug 2012 00:02:31 GMT</pubDate>
      <guid>https://trid.trb.org/View/1209995</guid>
    </item>
    <item>
      <title>Capacity of a shared lane</title>
      <link>https://trid.trb.org/View/1197480</link>
      <description><![CDATA[The traditional 'adjustment factor' and the new 'lane interaction' methods for estimating the capacity of a shared lane at a signalised intersection are discussed.  The adjustment factor method is needed when the shared lane is combined with adjacent lanes into a lane group with the same departure characteristics.  The lane interaction method as implemented in the sidra program employs a direct and explicit method to predict individual lane capacities without using adjustment factors.  The method allows for differences in the departure characteristics of shared lanes (eg, opposed turns and through traffic) and the adjacent lanes (eg, through traffic only) by treating the intervals of lane blockage as effective red (lost time).  This improves the prediction of not only the queue lengths and delays but also the short lane and opposed turn capacities.  A generalised model of lane blockage is employed for predicting the number of departures before being blocked.  A full intersection example is given with output from sidra to explain the lane interaction method.  Using this example, the relation between the lane interaction and adjustment factor methods are explained.  It is shown that substantial differences in capacity and performance predictions and timing solutions may result from the simplifying assumptions used to derive turn equivalents/ adjustment factors.  The adjustment factor method has been relevant to the simple manual analysis methods of the past.  Computerised analysis techniques have now found widespread use in the traffic engineering profession, and the method of modelling individual lane capacities explicitly and directly can be adopted without difficulty (a).]]></description>
      <pubDate>Fri, 24 Aug 2012 15:33:44 GMT</pubDate>
      <guid>https://trid.trb.org/View/1197480</guid>
    </item>
    <item>
      <title>Sidra-2 user guide</title>
      <link>https://trid.trb.org/View/1192648</link>
      <description><![CDATA[Sidra-2 is a computer program to aid traffic engineers and researchers in the design and analysis of signalised intersections.  It is based on the analytical techniques described in the ARRB research report arr no 123 (traffic signals: capacity and timing analysis).  Further improved techniques have been employed in sidra-2.  In particular, the capacity and performance calculations are carried out on a lane by lane basis.  Sidra-2 includes advanced techniques to solve the problems of opposed turns, short lanes and interaction of different movements in common lanes.  It also includes improved models of operating characteristics (delay, number of stops and queue length) and fuel consumption.  Basically, sidra-2 uses analytical models of traffic and iterative approximation methods of computation.  It is highly efficient in computer time usage.  This report provides a technical guide for sidra-2 users.  Sidra-2 input data are supplied on several card types which are explained in detail.  Input data errors and sidra-2 output information are also explained.  Complete examples of sidra-2 input and output are given. Sidra-2 output includes listing of basic movement and intersection variables, estimates of lane and movement flows, saturation flows and capacities, computed signal timings, a signal timing diagram, and performance measures for computed or specified signal timings with separate printouts for individual lanes and movements as well as summation for movement groupings specified by the user (a).]]></description>
      <pubDate>Fri, 24 Aug 2012 12:48:31 GMT</pubDate>
      <guid>https://trid.trb.org/View/1192648</guid>
    </item>
    <item>
      <title>Picady2: an enhanced program to model capacities, queues and delays at major/ minor priority junctions</title>
      <link>https://trid.trb.org/View/1187272</link>
      <description><![CDATA[An enhanced version of picady, a computer program which models capacities, queues and delays at major/ minor junctions, is described.  The program uses empirical formulae as a basis for the calculation of capacities and time dependent queueing equations for queue and delay predictions.  The enhancements include the facility (i) to model four arm junctions ie, crossroads, left right and right left staggers, (ii) to predict geometric delays and (iii) to include the effects of pedestrian (zebra) crossings adjacent to the junction.  Flared minor roads and the effects of major road right turning traffic blocking through traffic are also dealt with.  The enhancements result from recent empirical and analytical studies. Additionally, the flexibility of the program (now known as picady2) has been increased, with the availability of microcomputer and interactive versions. User inputs consist of various geometric characteristics of the junction, and traffic (and pedestrian) demand flow information (which may be specified in a number of ways).  Peak periods are usually modelled and capacities, queues and delays are calculated for each non priority traffic stream for each of a succession of short time segments (usually 10 or 15 minutes) within the period.  The user is able to assess the performance of both planned and existing layouts in terms of queueing delay and geometric delay.  Details of the required input parameters are given, the output is described and a full example is included (a).]]></description>
      <pubDate>Fri, 24 Aug 2012 07:07:44 GMT</pubDate>
      <guid>https://trid.trb.org/View/1187272</guid>
    </item>
    <item>
      <title>Traffic characteristics and intersection capacities I. traffic characteristics as related to highway capacity</title>
      <link>https://trid.trb.org/View/1178527</link>
      <description><![CDATA[]]></description>
      <pubDate>Fri, 24 Aug 2012 01:51:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/1178527</guid>
    </item>
  </channel>
</rss>