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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>
    <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>
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    <item>
      <title>Passenger Car Equivalency Factors Under Platooning Conditions</title>
      <link>https://trid.trb.org/View/1598088</link>
      <description><![CDATA[Heterogeneous traffic existing in developing countries such as in India is characterized by vehicles with very diverse static and dynamic characteristics. The various types of vehicles, other than cars in the heterogeneous traffic stream can be converted into equivalent passenger cars so as to express the heterogeneous traffic volume in terms of corresponding passenger car units (PCU). The subject of PCU has been studied on intercity, urban roads and at intersections controlled by traffic signals quite extensively. But studies on PCU values of vehicles on the downstream of signalized intersections have not been explored so far. The arterial links existing at downstream of traffic signals are designed to progress traffic with varying acceleration and deceleration. Vehicular interactions which take place within platoons and between platoons along such arterials are the predominant factors affecting vehicular progression. Hence there is a need to derive PCU values of vehicles along signalized corridors. The present study analyzes traffic flow data collected at the downstream of a signalized urban arterial to determine PCU values for various types of vehicles based on three methods. One method is the homogenisation coefficient method whereas the other one is the speed-area ratio method. The third one is a new method based on speed differential and area ratio is proposed in this paper which considers the effect of speed variation of vehicles for estimating PCU values. In this study, PCU values estimated based on speed differential-area ratio concept are found to be more logical compared to other methods as this method could incorporate the considerable variation in static and dynamic characteristics of various vehicles which progress along the downstream of intersections.]]></description>
      <pubDate>Mon, 15 Apr 2019 14:37:55 GMT</pubDate>
      <guid>https://trid.trb.org/View/1598088</guid>
    </item>
    <item>
      <title>A Lane-based Predictive Model of Downstream Arrival Rates in a Queue Estimation Model Using a Long Short-Term Memory Network</title>
      <link>https://trid.trb.org/View/1571852</link>
      <description><![CDATA[In this study, the authors develop a mathematical framework to predict cycle-based queued vehicles at each individual lane using a deep learning method – the long short-term memory (LSTM) network. The key challenges are to decide the existence of residual queued vehicles at the end of each cycle, and to predict the lane-based downstream arrivals to calculate vertical queue lengths at individual lanes using an integrated deep learning method. The primary contribution of the proposed method is to enhance the predictive accuracy of lane-based queue lengths in the future cycles using the historical queuing patterns. A major advantage of implementing an integrated deep learning process compared to the previously Kalman-filter-based queue estimation approach (Lee et al., 2015) is that there is no need to calibrate the co-variance matrix and tune the gain values (parameters) of the estimator. In the simulation results, the proposed method performs better in only straight movements and a shared lane with left turning movements.]]></description>
      <pubDate>Wed, 19 Dec 2018 16:25:18 GMT</pubDate>
      <guid>https://trid.trb.org/View/1571852</guid>
    </item>
    <item>
      <title>Evaluation of Downstream Merge Behaviors Resulting from Driver Lane Choice: A Driving Simulator Study</title>
      <link>https://trid.trb.org/View/1495878</link>
      <description><![CDATA[With the ever-increasing demand to add roadway capacity in a safe and efficient manner, the application of auxiliary through lanes (ATLs) at intersections has increased in recent years. Despite the potential capacity-related benefits, ATLs also introduce the potential for unique driver operation tactics, leading to challenging merge scenarios downstream of signalized intersections. Furthermore, the benefits of increasing capacity are only realized when drivers are making decisions that balance the utilization of the ATL and the adjacent continuous through lane. Moreover, balancing lane utilization upstream of an ATL signalized intersection may introduce an improvement in safety and operations in merging conflicts downstream. Previous research investigated the effectiveness of ATLs through microsimulation and field studies. This research employed two full-immersion driving simulation studies. The initial experiment was conducted using simulation technology to evaluate aspects of driver behavior associated with lane utilization at ATLs. Lane utilization of the ATL significantly increased when the driver was informed of the fundamental design concept, ultimately improving capacity. The second experiment was based upon the results of the initial experiment, coupled with ongoing research evaluating alternative merge signage. Specifically, the second experiment aimed to evaluate downstream merge signage that could mitigate some of the behaviors resulting from the less than optimal lane utilization for ATLs. With an emphasis on improving intersection performance, the results from this paper suggest that the implementation of alternative merging signage may lead to improved merging behavior.]]></description>
      <pubDate>Mon, 26 Feb 2018 13:44:44 GMT</pubDate>
      <guid>https://trid.trb.org/View/1495878</guid>
    </item>
    <item>
      <title>Priority Distribution in Signalized Intersections with Downstream Flow Restrictions</title>
      <link>https://trid.trb.org/View/1392351</link>
      <description><![CDATA[Signalized intersections are usually controlled with an aim to minimize delays, queues and lost time. The objective of signalized intersections may also be related to traffic safety or priority distribution. Relative saturation and lost time are often key parameters when calculating phase times and cycle lengths. However, when queue spillbacks block the intersection exits, the traditional Signal Phasing and Timing (SPAT) methods may not be the appropriate approach. The first aim of this paper is to investigate the effectiveness of traditional signal timing when it comes to priority distribution during various conditions. This is documented through a literature review, field observations and hypothesis testing. The second aim is to contribute towards improved distribution of priority during the most demanding conditions, mainly in severely oversaturated intersections with blockages due to queue spillbacks from downstream bottlenecks. Based on existing knowledge combined with new ideas, the last parts of this paper outline an alternative approach, Signal Phasing and Counting (SPAC). Although the main focus is on improving priority distribution, the results from microsimulation and analytical models also suggest that delays for movements without downstream flow restrictions may be significantly reduced.]]></description>
      <pubDate>Sat, 02 Apr 2016 16:01:55 GMT</pubDate>
      <guid>https://trid.trb.org/View/1392351</guid>
    </item>
    <item>
      <title>Local ramp metering with distant downstream bottlenecks: A comparative study</title>
      <link>https://trid.trb.org/View/1395759</link>
      <description><![CDATA[The well-known feedback ramp metering algorithm ALINEA can be applied for local ramp metering or included as a key component in a coordinated ramp metering system. ALINEA uses real-time occupancy measurements from the ramp flow merging area that may be at most a few hundred meters downstream of the metered on-ramp nose. In many practical cases, however, bottlenecks with smaller capacities than the merging area may exist further downstream, which suggests using measurements from those downstream bottlenecks. Recent theoretical and simulation studies indicate that ALINEA may lead to poorly damped closed-loop behavior in this case, but PI-ALINEA, a suitable Proportional-Integral (PI) extension of ALINEA, can lead to satisfactory control performance. This paper addresses the same local ramp-metering problem in the presence of far-downstream bottlenecks, with a particular focus on the employment of PI-ALINEA to tackle three distinct cases of bottleneck that may often be encountered in practice: (1) an uphill case; (2) a lane-drop case; and (3) an un-controlled downstream on-ramp case. Extensive simulation studies are conducted on the basis of a macroscopic traffic flow model to show that ALINEA is not capable of carrying out ramp metering in these bottleneck cases, while PI-ALINEA operates satisfactorily in all cases. A field application example of PI-ALINEA is also reported with regard to a real case of far downstream bottlenecks. With its control parameters appropriately tuned beforehand, PI-ALINEA is found to be universally applicable, with little fine-tuning required for field applications.]]></description>
      <pubDate>Mon, 29 Feb 2016 16:57:14 GMT</pubDate>
      <guid>https://trid.trb.org/View/1395759</guid>
    </item>
    <item>
      <title>Local Ramp Metering with Distant Downstream Bottlenecks: A Comparative Study</title>
      <link>https://trid.trb.org/View/1349288</link>
      <description><![CDATA[The well-known feedback ramp metering algorithm ALINEA can be applied for local ramp metering or included as a key component in a coordinated ramp metering system. ALINEA uses real-time occupancy measurements from the ramp flow merging area that may be at most few hundred meters downstream of the metered on-ramp nose. In many practical cases, however, bottlenecks with smaller capacity than the merging area may exist further downstream for various reasons, which suggests using measurements from those further downstream bottlenecks. Recent theoretical and simulation studies indicate that ALINEA may lead to a poorly damped closed-loop behavior in this case, but PI-ALINEA, a suitable Proportional-Integral (PI) extension of ALINEA, can lead to satisfactory control performance. This paper addresses the same local ramp-metering problem in the presence of downstream bottlenecks, with a particular focus on the general capacity of PI-ALINEA with three distinct types of bottleneck that may often be encountered in practice, i.e. (1) an uphill case; (2) a lane-drop case; (3) an uncontrolled on-ramp case. Extensive simulation studies are conducted using a macroscopic traffic flow model to demonstrate that the performance of ALINEA indeed deteriorates in each of these bottleneck cases, while significant improvement is obtained using PI-ALINEA in all cases. Moreover, with its control parameters appropriately tuned beforehand, PI-ALINEA is found to be universally applicable, with little fine-tuning required for field applications.]]></description>
      <pubDate>Thu, 30 Apr 2015 09:25:25 GMT</pubDate>
      <guid>https://trid.trb.org/View/1349288</guid>
    </item>
    <item>
      <title>Proportion-Based and Tendency-Based Bus Trajectory Prediction Models</title>
      <link>https://trid.trb.org/View/1259543</link>
      <description><![CDATA[At the terminal station, the path headway bias of a trip is linearly correlated to the travel time of the path when it is beyond a critical range, which marks the tendency between successive trips. A tendency-based model for trajectory prediction was proposed in which the path headway bias was assumed to be proportionally amplified at downstream stops with an increase in path travel time, when buses fall into the amplifying tendency, or remain the same, when buses fall into the maintaining tendency. The boundary of the tendency was calibrated by the relative performance between the proportion-based model and the history-based model. The calibrated tendency-based model succeeds in avoiding the amplification of nondirectional path headway bias in the proportion-based model by keeping buses in the maintaining tendency and promoting the amplification of directional path headway bias by allowing buses to fall into the amplifying tendency.]]></description>
      <pubDate>Tue, 03 Sep 2013 12:29:55 GMT</pubDate>
      <guid>https://trid.trb.org/View/1259543</guid>
    </item>
    <item>
      <title>Calculation of Additional Lost Green Time at Closely Spaced Intersections</title>
      <link>https://trid.trb.org/View/1253218</link>
      <description><![CDATA[At closely spaced signalized intersections or interchanges, additional lost green time can occur at upstream intersections when there is a queue spillback. For an accurate estimation of capacities and delays at closely spaced intersections, it is necessary to account such additional lost time. The Highway Capacity Manual (HCM) 2010 provides a model for the estimation of the additional lost time due to the presence of a downstream queue. However, case studies indicate that the HCM model does not provide a very accurate estimation when the distance to the downstream queue is short. In this paper, a new model is developed for the estimation of additional lost time considering queue discharge patterns and traffic flow patterns. Simulation results show that the proposed model provides a more accurate estimation of additional lost time compared with the HCM model when the distance to the downstream queue is limited.]]></description>
      <pubDate>Thu, 20 Jun 2013 16:38:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/1253218</guid>
    </item>
    <item>
      <title>Capacity drops at merges: An endogenous model</title>
      <link>https://trid.trb.org/View/1123048</link>
      <description><![CDATA[The Newell-Daganzo merge model is not only very simple but also accurately reproduces experimental findings. However, the capacity downstream of the merge is an exogenous variable in the model. This is a serious limitation for merges that behave as active bottlenecks because their downstream capacity is a direct consequence of the merging behavior. This paper proposes an analytical model that extends the Newell-Daganzo model by incorporating, endogenously, the capacity drop related to the merging process. Two cases are investigated depending on the traffic states on the on-ramp. The model properties are analyzed and a sensitivity analysis is performed to quantify the relative contribution of the each parameter in the capacity drop. Finally, the extended Newell-Daganzo model is validated with experimental data coming from an active merge bottleneck on the M6 freeway in UK.]]></description>
      <pubDate>Fri, 16 Dec 2011 14:48:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/1123048</guid>
    </item>
    <item>
      <title>Capacity Drops at Merges: An Endogenous Model</title>
      <link>https://trid.trb.org/View/1105318</link>
      <description><![CDATA[The Newell-Daganzo merge model is not only very simple but also accurately reproduces experimental findings. However, the capacity downstream of the merge is an exogenous variable in the model. This is a serious limitation for merges that behave as active bottlenecks because their downstream capacity is a direct consequence of the merging behavior. This paper proposes an analytical model that extends the Newell-Daganzo model by incorporating, endogenously, the capacity drop related to the merging process. Two cases are investigated depending on the traffic states on the on-ramp. The model properties are analyzed and a sensitivity analysis is performed to quantify the relative contribution of the each parameter in the capacity drop. Finally, the extended Newell-Daganzo model is validated with experimental data coming from an active merge bottleneck on the M6 freeway in UK.]]></description>
      <pubDate>Thu, 21 Jul 2011 10:08:09 GMT</pubDate>
      <guid>https://trid.trb.org/View/1105318</guid>
    </item>
    <item>
      <title>Travel Times in Virtual DMS</title>
      <link>https://trid.trb.org/View/1104077</link>
      <description><![CDATA[A “Virtual DMS” method has been created for presenting travel time information to callers of the North Carolina 511 traveler information telephone service (NC 511). When travel time information is presented to drivers on Dynamic Message Signs (DMS), the travel times reported are measured from the physical DMS to a downstream location, such as a cross street or interchange. As such, the traveler’s location and direction of travel are fixed. This presentation format is much different than traditional 511 travel time dissemination where the caller’s location and direction of travel is not only variable but the caller could be calling from, or could be interested in, any roadway. North Carolina combined the best of both DMS and traditional 511 travel time presentation, providing callers their travel times to downstream exits based on their current location and travel direction; termed “Virtual DMS”.]]></description>
      <pubDate>Thu, 23 Jun 2011 09:07:24 GMT</pubDate>
      <guid>https://trid.trb.org/View/1104077</guid>
    </item>
    <item>
      <title>Evaluation of the Effectiveness of a Variable Advisory Speed System on Queue Mitigation in Work Zones</title>
      <link>https://trid.trb.org/View/1104109</link>
      <description><![CDATA[Variable Advisory Speed Systems (VASSs) provide drivers with advanced warning regarding traffic speeds downstream to help them make better decisions. Vehicle use on highways is increasing and the need to improve highways brings increased construction of highways, which increases the need for reducing the number of traffic lanes thus reducing capacity during construction. This often causes queues at the entrance to work zones. The purpose of this study was to evaluate the effectiveness of a VASS at mitigating queues in work zone entrances. It was anticipated that by implementing a VASS queues would be reduced and vehicle flow increased in work zone areas. Three objectives of this study are: (1) research VASS systems that can be tested, (2) select and deploy a VASS in Utah at a long-term work zone, (3) perform a statistical analysis on traffic flow characteristic data to evaluate the effectiveness of the VASS that was deployed. A literature review on use of VASSs for work zones showed minimal research had been done on VASSs. A VASS was selected and the work zone for the study was selected as the I-15 Beck Street Widening Project. The VASS consisted of five sensors and two variable message signs (VMSs). To determine if the system was effective at reducing queues, the speed data were analyzed to come to statistical conclusions. It was concluded that the VASS investigated was effective on weekends during evening peak hours when there was traffic slow down. There was no statistical difference on any day of the week when there was no slow down. It was recommended, however, that further studies be conducted to evaluate more about the system.]]></description>
      <pubDate>Tue, 07 Jun 2011 16:20:16 GMT</pubDate>
      <guid>https://trid.trb.org/View/1104109</guid>
    </item>
    <item>
      <title>Delay Analysis of a Traffic Signal Phase Termination Algorithm Using Computer Simulation</title>
      <link>https://trid.trb.org/View/1091690</link>
      <description><![CDATA[Downstream congestion can create additional delay at signalized intersections due to queue spillback, a problem which may be mitigated by using a phase truncation algorithm.  The implementation of this algorithm is achieved through the use of a logic processor embedded in an off-the-shelf traffic controller, programmed to terminate the subject phase when flow drops below a specified threshold.  Two parameters control the aggressiveness of this algorithm: a filter value which specifies the time before the algorithm begins searching for an opportunity to terminate the affected phase; and the headway value which designates the maximum allowable vehicle gap time before the algorithm terminates the phase.  Simulations were conducted to determine the impact of varying these parameters on intersection delay at a test intersection operating under oversaturated conditions.  The early termination of a turning movement that is blocked by downstream congestion is shown to alleviate delay for the competing through movement at the intersection.  Though overall intersection delay is not significantly impacted under the test conditions, the truncation algorithm may be a viable solution for situations where substantial delay is experienced for the through movements.  In addition, the truncation logic also provides a viable tool for reporting downstream restriction problems to practitioners in near real-time.]]></description>
      <pubDate>Mon, 18 Apr 2011 12:24:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/1091690</guid>
    </item>
    <item>
      <title>Are Some Freeway Lanes Under-utilized?</title>
      <link>https://trid.trb.org/View/1092620</link>
      <description><![CDATA[Geometric design of a roadway segment affects its throughput and capacity. One of the key factors impacting the basic freeway segment operations in urban areas is the density of ramps. Entry and egress flows associated with ramps create turbulence in the traffic stream and affect the distribution of vehicles across lanes on main freeway segments. The impact of ramps on basic freeway segments is accounted for within the Highway Capacity Manual (HCM) method for estimating free-flow speed (FFS), which is utilized in capacity and level of service estimation. However, the HCM method does not distinguish minor ramps (e.g., arterial-to-freeway) from major ramps (e.g., freeway-to-freeway) and their relative locations (i.e., whether in the upstream or downstream) and does not provide any methods to account for their impacts on the throughput when FFS is known or measured. To better capture the impacts of ramps, lane utilization variation (measured by lane utilization factor) across urban freeway lanes is analyzed and modeled in this paper. This paper explores lane utilization behavior on urban basic freeway segments in high flow situations. Traffic volume and roadway geometric data from 11 basic freeway segment sites in Hampton Roads, Virginia are used for the analysis. Descriptive analysis of the data is provided, followed by rigorous statistical models (ordinary least squares and truncated regression) that are estimated to identify important factors associated with lane utilization variation. Lane utilization behavior is found to be affected differently by ramp types and their relative locations from the freeway segment being analyzed. More specifically, freeway-freeway ramps have more impact than arterial-freeway ramps, and downstream ramps have more impact than their counterparts.]]></description>
      <pubDate>Mon, 18 Apr 2011 12:24:30 GMT</pubDate>
      <guid>https://trid.trb.org/View/1092620</guid>
    </item>
    <item>
      <title>Investing Boundary Issues Arising from Congestion Charging in a Bottleneck Scenario</title>
      <link>https://trid.trb.org/View/934172</link>
      <description><![CDATA[The purpose of this chapter is to highlight and consider boundary issues arising from congestion charging when using the  dynamic equilibrium analysis approach in a bottleneck scenario and also to examine implications for design and implementation of congestion charging projects in the future. The authors have formulated a unique bottleneck model composed of two parts: one is to link with a limited capacity and the other is a deterministic queue model at the entry of the link, in which the queue exists only when the departure rate is greater than the receiving capacity of the downstream link.]]></description>
      <pubDate>Thu, 16 Sep 2010 12:42:19 GMT</pubDate>
      <guid>https://trid.trb.org/View/934172</guid>
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