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    <title>Transport Research International Documentation (TRID)</title>
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    <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>
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      <link>https://trid.trb.org/</link>
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    <item>
      <title>A full-sample longitudinal trajectory reconstruction framework for signalized intersection approach lanes in a vehicle-infrastructure cooperation environment</title>
      <link>https://trid.trb.org/View/2762379</link>
      <description><![CDATA[Vehicle trajectories contain abundant spatial–temporal information that can be utilized for traffic state estimation and parameter optimization. In the vehicle-infrastructure cooperation environment, connected automated vehicles (CAVs) can provide their trajectory data and perceive the trajectory data of nearby vehicles within a specific range. Moreover, these trajectory data can be shared and cross-validated with fixed detectors, offering a novel solution for reconstructing full-sample vehicle trajectories at the signalized intersection. Based on the car-following (CF) model, this paper proposes a trajectory reconstruction framework that integrates CAVs sensing data and camera detection data. This framework can solve the trajectory reconstruction problem for regular vehicles (RVs) between any two consecutive CAVs on the lane. It comprises four key modules: the trajectory reconstruction model (TRM) based on the trailing CAV (TTRM), the TRM based on the leading CAV (LTRM), the Modified LTRM, and the fusion algorithm (FA). Furthermore, NGSIM and simulation data are utilized to validate and analyze the performance of the proposed framework under various CAV penetration rates (PRs) and traffic demands. Results indicate that: (1) compared to the state-of-the-art CF-based algorithms, the proposed framework significantly reduces in terms of position error, queuing position error, moving position error, time error, speed error, and acceleration error with average RMSE reductions of 83.45%, 20.97%, 90.87%, 85.54%, 30.39%, and 28.64% in NGSIM data, respectively, and even more substantial decrease in simulation data. (2) The framework maintains acceptable error rates across different PRs of CAVs and varying traffic volumes. (3) The framework is robust for different CF model parameters in simulation data. The findings can support signalized intersection management and control in the vehicle-infrastructure cooperation environment.]]></description>
      <pubDate>Thu, 10 Sep 2026 16:58:35 GMT</pubDate>
      <guid>https://trid.trb.org/View/2762379</guid>
    </item>
    <item>
      <title>A study on lane-changing risk evolution of vehicle group based on potential field model in the freeway tunnel approach section</title>
      <link>https://trid.trb.org/View/2507290</link>
      <description><![CDATA[In the freeway tunnel approach section, lane-changing behaviors and transitions in the driving environment exacerbate traffic flow disruptions, increase driving risks, and lead to a higher accident rate. To this end, this study presents a method to explore the risk evolution process of lane-changing in these sections and evaluate its impact on traffic flow operations surrounding lane-changing vehicles. First, a driving risk potential field model based on the field theory, which consists of a vehicle kinetic potential field and a tunnel illumination potential field, is proposed to evaluate the driving risk. Furthermore, a “vehicle group” risk graph was constructed based on graph theory, incorporating both a node-coupling driving risk model and a topological potential entropy model. Finally, trajectory datasets were collected through naturalistic driving tests to analyze the evolution of lane-changing risk and the stability of the vehicle group. From the analysis of coupling driving risk evolution, the authors found that in the [100, 500) m, [500, 1000) m, and [1000, 1500) m freeway tunnel approach sections, the coupled driving risk of lane-changing vehicle (LCV) was higher than that of the other vehicles in the vehicle group. In different tunnel approach sections, LCVs that received the highest risk were from different vehicles in vehicle group. LCVs received the highest field strength from the risk potential fields of the lateral vehicle (LV), front lateral vehicle (FLV), and front vehicle (FV) in the [100, 500) m, [500, 1000) m, [1000, 1500) m tunnel approach sections, respectively. Based on the absolute value of the vehicle group topological potential entropy, the authors observed the resilience of the vehicle group system improved with increasing distance from the tunnel entrance. Traffic flow regained stability more quickly after lane-changing disturbances in sections farther from the tunnel entrance. This study highlights that the section closer to the freeway tunnel entrance significantly impact lane-changing risk, and it takes longer for the vehicle group to recover its stability after a lane-changing disturbance. The research results offer a theoretical and methodological foundation for enhancing traffic safety measures and developing microscopic driving behavior models for freeway tunnel approach sections.]]></description>
      <pubDate>Tue, 18 Mar 2025 15:48:12 GMT</pubDate>
      <guid>https://trid.trb.org/View/2507290</guid>
    </item>
    <item>
      <title>Exploring the Mechanism for Increased Risk in Freeway Tunnel Approach Zones: A Perspective on Temporal-spatial Evolution of Driving Predictions, Tasks, and Behaviors</title>
      <link>https://trid.trb.org/View/2488350</link>
      <description><![CDATA[Freeway tunnel approach zones, situated outside the tunnel, do not undergo the same sudden changes in luminous environment and visual references that entrance zones experience. Despite this, accident data indicates that approach zones present similar safety risks to entrance zones, both of which are significantly higher than other tunnel sections. The reasons for the heightened risks in approach zones remain unclear in existing research. To address this knowledge gap, this study conducted real vehicle tests and subjective perception experiments. The Task Analysis of Driving Scenarios (TADS) was employed to analyze driving behavior patterns and develop a set of evaluation metrics, including four key driving behavior nodes (P1_SGD, P2_EF, P3_FF, P4_SAD), safety and efficacy indices for active deceleration behaviors (I1_ADS, I2_ADE), and two indicators for understanding anomalous behaviors (SR, AOI_PFN). By skillfully selecting scenarios to control variables, this research examined how limited visibility in tunnel approach zones and spatial intervisibility tunnels contribute to safety risks in these zones. Additionally, the Predictive Processing Model (PPM) was used to elucidate the temporal and spatial evolution of driving predictions, tasks, and behaviors under normal conditions. The findings reveal that, although heavy driving tasks cannot be avoided, under normal conditions, predictions develop gradually with minimal prediction errors, enabling effective navigation. However, limited visibility in tunnel approach zones and spatially intervisible tunnels lead to inaccuracies and deviations in predictions, resulting in significant prediction errors as drivers approach the tunnel. This causes more aggressive driving behaviors, disrupting the delicate balance of predictions and tasks.]]></description>
      <pubDate>Mon, 10 Feb 2025 09:25:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/2488350</guid>
    </item>
    <item>
      <title>Estimating lane utilization for variable approach lanes using explainable machine learning</title>
      <link>https://trid.trb.org/View/2289727</link>
      <description><![CDATA[This study investigates the flow distribution patterns at intersection approaches with variable approach lanes (VALs) and proposes a new lane utilization adjustment factor specifically for VALs. Unmanned aerial vehicles (UAVs) were used to collect naturalistic data, including traffic flow, approach geometry, and signal control-specific information, at selected intersections in Hangzhou, China. Machine learning techniques were employed to develop accurate regression models for estimating lane utilization, separately for the two VAL statuses. Preliminary analyses indicate different VAL utilization patterns across sites, suggesting the presence of external factors, beyond the VAL control itself, influencing the VAL utilization. The machine learning regression models provide insights into these factors by ranking them based on the importance and the impact magnitude. From a practical standpoint, this study recommends the implementation of uniform lane guiding signs, lane geometry improvements, and driver education to enhance the operational efficiency of variable approach lanes.]]></description>
      <pubDate>Tue, 30 Jan 2024 09:25:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/2289727</guid>
    </item>
    <item>
      <title>Vehicle Emission Comparisons along Electronic and Manual Toll Collection Lanes</title>
      <link>https://trid.trb.org/View/2000788</link>
      <description><![CDATA[This paper evaluated the passenger cars’ emission levels for two kinds of highway toll collection lanes (electronic toll collection and manual toll collection) in China. The traffic flow characteristics, including speed, volume, delay, queue length, and the real-time emission data of CO, HC, NOx, CO₂ on electronic toll collection (ETC) and manual toll collection (MTC) lanes, were collected with unmanned aerial vehicle (UAV) and AUTOplus, respectively. Volume concentrations of vehicle emissions were converted into mass emission rates and emission factors for further analyses. The parameters of vehicle specific power (VSP) were calibrated and its distribution under on-road driving conditions was explored. T tests were conducted to examine the significant difference on two different lanes for emissions and traffic operations. According to traffic flow characteristics, the ETC system was found to obviously increase vehicle speed and reduce delay and queue length. In addition, the emissions of four pollutants on MTC lanes were much higher than those on ETC lanes.]]></description>
      <pubDate>Wed, 19 Jul 2023 09:38:29 GMT</pubDate>
      <guid>https://trid.trb.org/View/2000788</guid>
    </item>
    <item>
      <title>Empirical Analysis of Traffic Flow Characteristics at Variable Approach Lanes</title>
      <link>https://trid.trb.org/View/2146932</link>
      <description><![CDATA[It is interesting that despite its long-term and widespread use in China, relatively little is known about the operational characteristics of a variable approach lane (VAL) in real world. Using one month of inductive-loop detector data at ten dynamic approaches (intersection approaches with dynamic lane assignment) from 21 different intersections in Hangzhou, China, this paper presents the results of a study materializing the flow characteristics of variable approach lanes by comparing them with adjacent normal-flow lanes under various operating conditions. The effectiveness of the results was examined in a case-control analysis by integrating 12 fixed approaches (without variable lane) as benchmark. It was found that the difference or similarity of flow rate between the variable lane and the normally-flowing lane differs under a variety of traffic volume, time-of-day, mode-of-operation, and overhead lane-use guidance sign (OHS) location conditions. The study also revealed that while naturally there may be a difference in flow rate between referencing lanes at fixed approaches, nevertheless the flow difference percentage (FDP) at dynamic approaches is significantly higher.]]></description>
      <pubDate>Wed, 24 May 2023 09:06:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/2146932</guid>
    </item>
    <item>
      <title>Analysis of Congestion Evolution at Four-Leg Signalized Intersections</title>
      <link>https://trid.trb.org/View/1990316</link>
      <description><![CDATA[The intersection congestion is the smallest unit of urban road network congestion. This paper takes four-leg signalized intersections as the research object, and studies congestion evolution. First, according to survey data, congestion indexes of four-leg signalized intersections considering user experience are proposed, including number of stops, maximum queue length, speed, saturation, and intersection delay. Second, congestion evolution is explored in experiments using microscopic simulation software. Intersection input volume follows three patterns: linear increasing flow, increasing as pulses, and increasing as steps. Third, this paper discusses congestion changes when approaches are widened and left-turns are prohibited. The results show that intersection congestion lags behind increasing demand; for pulse increase demand, congestion discharge speed is faster than congestion formation; the speed and degree of traffic congestion at approach widened intersections are lower than those without widening under the same traffic demand conditions; traffic congestion at full-direction intersections is more serious than at left-turn prohibited intersections.]]></description>
      <pubDate>Wed, 21 Dec 2022 09:17:48 GMT</pubDate>
      <guid>https://trid.trb.org/View/1990316</guid>
    </item>
    <item>
      <title>Drivers’ Adaptability of the Variable Approach-Lane at Signalized Intersections</title>
      <link>https://trid.trb.org/View/1990312</link>
      <description><![CDATA[With the rapid growth of vehicles, signalized intersection congestion is getting worse. Variable approach-lanes were applied as one of the new engineering measures, which can adjust the steering function of the approaches (generally left-turn/straight and right-turn/straight) according to the traffic flow in different directions at different time periods. A growing number of cities have started promoting the use of variable approach-lanes. However, a preliminary investigation indicated that the utilization of variable approach-lanes is not very high. An ordered probit model was established to analyze factors that affect the adaptability of drivers based on a questionnaire survey. The results showed that gender, driving age, length of residency in Hangzhou, roadside traffic signs, signal indicator, and pre-signals had significant correlations with utilization of variable approach-lanes. Some effective strategies were presented to provide a reliable basis for authorities to develop better traffic control and management measures.]]></description>
      <pubDate>Tue, 20 Dec 2022 09:12:14 GMT</pubDate>
      <guid>https://trid.trb.org/View/1990312</guid>
    </item>
    <item>
      <title>Research on Vehicle Operation Characteristics in Intersections’ Entrance Marking Vacuum Zone of a Mountainous City</title>
      <link>https://trid.trb.org/View/2019059</link>
      <description><![CDATA[This paper uses an unmanned aerial vehicle (UAV) to video the traffic flow of an urban intersection entrance road to explore vehicle movement characteristics in the marking vacuum zone (MVZ). A methodological framework is developed, mainly involving the following five stages: image registration, background elimination and image preprocessing, contour fitting and vehicle determination, detector setup and vehicle detection, and vehicle tracking. Various rules of vehicle trajectory, velocity, and acceleration in the MVZ are analyzed in detail. Results show that the running speed of the vehicle offers a slow downward trend in the MVZ, and the entrance speed is higher than the exit speed. Straight vehicles are more inclined to choose Lane III to enter the intersection. The number of track intersections is positively correlated with traffic risk. This research can support traffic management and traffic simulation model calibration.]]></description>
      <pubDate>Thu, 17 Nov 2022 10:15:20 GMT</pubDate>
      <guid>https://trid.trb.org/View/2019059</guid>
    </item>
    <item>
      <title>Improved FVD Model for Signalized Intersection Vehicle Lane-Changing</title>
      <link>https://trid.trb.org/View/2019032</link>
      <description><![CDATA[To objectively describe the lane-changing behavior of the mixed flow of cars and buses in the inlet lane of urban signal intersections, an improved full velocity difference model (FVD) model was constructed by introducing a FVD car-following model in the specific process of vehicle lane-changing, considering the effects of vehicle type and driver attributes, defining the vehicle safety spacing as a function of velocity, and classifying the lane-changing behavior into four specific forms. Afterward, the lane-changing video clips taken at the approach road at the intersection were analyzed in tracker software to obtain data, and a matlab elite genetic algorithm was applied to calibrate the model parameters. The results show that, compared with the traditional FVD lane change model, the improved model is significantly improved and more consistent with the lane-changing behavior of heterogeneous traffic in the intersection inlet lane, while it provides a theoretical basis for modeling microscopic traffic flow.]]></description>
      <pubDate>Thu, 17 Nov 2022 10:15:19 GMT</pubDate>
      <guid>https://trid.trb.org/View/2019032</guid>
    </item>
    <item>
      <title>Headway Data Extraction and Highway Capacity Manual Capacity Function Calibration for Roundabouts With Roadside Lidar Data</title>
      <link>https://trid.trb.org/View/2060029</link>
      <description><![CDATA[There have been many research efforts analyzing roundabouts to extract the gap acceptance parameters of critical and follow-up headways at the entry lanes, but most have not had automatic methods of outputting the desired headways. This paper proposes an automatic method for extracting headway information at roundabouts with roadside lidar data and demonstrating the use of the headway output for Highway Capacity Manual (HCM) roundabout capacity function calibration. The advantages of using roadside lidar sensors over video cameras are that it is less computationally demanding, has a greater detection range, and is effective in all lighting conditions. Roadside lidar provides high accuracy cloud points of all road users that can be converted into geolocated trajectories using software developed by the University of Nevada, Reno (UNR). Headway is then extracted using an ArcGIS plugin of Python Scripts developed by the authors. Roadside lidar data were collected at one roundabout in Reno, Nevada, United States during the daytime hours, and headway data were extracted from the trajectory output. With rejected, accepted, and follow-up headways extracted, Raff’s Method was employed to extract the critical headway and the average of the follow-up headways was calculated. These values were used to determine the entry capacity at a roundabout. The results for the capacity were validated with industry standard equations, providing evidence for an automatic method to extract crucial operational information. The methodology proposed in this paper opens the door for several more extended studies with roundabouts, vehicle-pedestrian interactions, and on-ramp merging events.]]></description>
      <pubDate>Mon, 14 Nov 2022 14:50:43 GMT</pubDate>
      <guid>https://trid.trb.org/View/2060029</guid>
    </item>
    <item>
      <title>Saturation flow rate analysis for special width approach lanes: An empirical study in Karlsruhe, Germany</title>
      <link>https://trid.trb.org/View/2012451</link>
      <description><![CDATA[The special width approach lane (SWAL) is a newly proposed unconventional design, whereby a wide approach lane is divided into two narrower lanes. The design entails the use of a single lane by two passenger cars or one heavy vehicle. Such design has been applicated at signalized intersections of Karlsruhe, Germany. This paper focuses on the saturation flow rate analysis since most existing studies on such design rely on the default highway capacity manual (HCM) values. Saturation flow rate data was collected at four SWAL design based signalized intersections with procedural steps of the HCM 2010 using the video camera. The two-sample t-test was performed to explore the potential influencing factors, and then the non-linear regression analysis was conducted to estimate the saturation flow rate of SWAL. The proposed model can effectively depict the saturation flow rate with lane marking, presence of cyclists, and rainfall being the influencing factors. The overall accuracy of the proposed model is about 95%. The results indicate that the three influencing factors are independent of each other. The existence of cyclists and rainfall lead to a decrease in the saturation flow rate, while the lane markings can improve the saturation flow rate. Moreover, the SWAL works well in Karlsruhe, Germany. The model predicts a base saturation flow rate value of 1652 pcu/h/ln, which is plausible with comparison of the base saturation flow rate recommended in the German Highway Capacity Manual.]]></description>
      <pubDate>Tue, 30 Aug 2022 09:20:17 GMT</pubDate>
      <guid>https://trid.trb.org/View/2012451</guid>
    </item>
    <item>
      <title>Before–After Evaluation of Left-Turn Lane Extension Considering Injury Severity and Collision Type</title>
      <link>https://trid.trb.org/View/1709495</link>
      <description><![CDATA[Left-turn lanes are commonly used to provide space to accommodate vehicle deceleration and provide adequate storage of turning vehicles. The objective of this study is to evaluate the safety effectiveness of extending the length of left-turn lanes at signalized intersection approaches. Five years of collision data including injury severity and collision type from three treatment sites and 31 comparison sites in the City of Surrey, Canada were used in the study. The analysis focused on target crashes including left-turn-related rear-end and left-turn-related sideswipe collisions. A full Bayesian (FB) before–after analysis was conducted for all collisions, severity levels, and collision types. Multivariate Poisson–lognormal linear intervention models were used for the analysis. The treatment effectiveness index was calculated to quantitatively measure the effectiveness of the safety treatment. The FB before–after results showed that the treatment-related collisions were reduced by 57.4% following the implementation of extended left-turn lane. The reduction in injuries and fatalities collisions (63.8%) was greater than that in property damage only collisions (55.7%). The decrease in rear-end collisions (62.8%) was greater than that in sideswipe collisions (58.1%). The findings indicate a remarkable improvement in safety after the length extension of the left-turn lane.]]></description>
      <pubDate>Mon, 15 Jun 2020 11:23:32 GMT</pubDate>
      <guid>https://trid.trb.org/View/1709495</guid>
    </item>
    <item>
      <title>Impact of the Rural Intersection Active Warning System (RIAWS) on Driver Speed: A Driving Simulator Study</title>
      <link>https://trid.trb.org/View/1704876</link>
      <description><![CDATA[The Rural Intersection Active Warning System (RIAWS) is an innovative road safety treatment designed to slow traffic on major approaches to a high-risk rural intersection when vehicles are turning or crossing into or out of the side roads, thus reducing fatal and serious casualties. A 2 × 2 experimental driving simulation study was undertaken which aimed to determine the impact of signage (RIAWS versus traditional painted) and sign content (80 km/h versus slow down) on drivers’ instantaneous speed at rural intersections. The driving simulator assessment was completed by 96 drivers aged between 18 and 80 years with a current WA C class license (passenger vehicle). This provided a total of 384 observations. The results of a two-way ANOVA found a significant interaction effect between speed signage and sign content (F(1,3) = 11.78, p < 0.001). The RIAWS “80 km/h” sign resulted in significantly lower instantaneous speeds than all other types of signs including RIAWS “slow down signs (p < 0.001), traditional painted “80 km/h” signs (p = 0.023) and traditional painted “slow down” signs (p = 0.001). Overall, the study found that RIAWS “80 km/h” sign and not the RIAWS “slow down” sign provided the most effective option for reducing driver speeds on approach to rural intersections. Further research is needed to determine the most effective placement of the RIAWS “80 km/h” signs and how they perform on curved roads.]]></description>
      <pubDate>Tue, 09 Jun 2020 10:43:31 GMT</pubDate>
      <guid>https://trid.trb.org/View/1704876</guid>
    </item>
    <item>
      <title>Safety Evaluation of Discontinuous Lane Design of Intersection Approach in China</title>
      <link>https://trid.trb.org/View/1629817</link>
      <description><![CDATA[A special kind of road marking design denoted as discontinuous lane design is prevailing in most cities of China, in which a changeover portion between the upstream road segment and the approach of intersection is void of road markings. This article evaluates the road safety and traffic efficiency of the discontinuous lane design for the most typical case that three lanes upstream are followed by four approaching lanes to the intersection. A safety risk comparison was made between the discontinuous lane design and its counterpart continuous lane design by index of postencroachment time (PET). Then, using an ordered probit model, the PETs, representing the severity of traffic conflict, were linked to relevant variables including the traffic volume, the queue length of target lane on the approach, the queue length of the neighboring target lane, the upstream lane used by the vehicle, the vehicle speed before entering the discontinuous zone, and so on. It was found that the upstream lane has an important effect on traffic safety under discontinuous lane design. Continuous lane design is only recommended for intersection approaches with relatively stable right and left turning flows, and not appropriate for specific cases when the turning flows fluctuate significantly in daily periods.]]></description>
      <pubDate>Wed, 28 Aug 2019 17:16:37 GMT</pubDate>
      <guid>https://trid.trb.org/View/1629817</guid>
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