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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>
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      <title>Transport Research International Documentation (TRID)</title>
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      <link>https://trid.trb.org/</link>
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    <item>
      <title>A Machine Learning Method to Decide the Start Position of Mandatory Lane Changes before Expressway Exits</title>
      <link>https://trid.trb.org/View/2562223</link>
      <description><![CDATA[Mandatory lane changes are essential for vehicles, particularly autonomous ones, preparing to exit expressways. The longitudinal position to initiate lane changes significantly impacts traffic safety, efficiency, and exit success probability. Previous studies primarily used fixed or discretized values for the start position, focusing on two-lane settings mostly. This paper presents a method for determining the optimal starting position for lane changes on multi-lane expressways, leveraging traffic simulations for data collection and machine learning to develop probabilistic models. We analyze simulation data to identify successful end positions and employ Probability Density Estimation (PDE) and Gaussian Process Regression (GPR) to assess success probabilities under varying conditions. This adaptive model offers real-time guidance for various vehicle types, including automated cars and truck platoons, enhancing safety and upstream traffic flow efficiency compared to traditional approaches. Our findings highlight significant differences in start position requirements among different vehicle categories upon exit.]]></description>
      <pubDate>Fri, 20 Feb 2026 15:28:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/2562223</guid>
    </item>
    <item>
      <title>When there is no rush to take over: Evaluating multi-stage takeover request designs in conditionally automated driving</title>
      <link>https://trid.trb.org/View/2642406</link>
      <description><![CDATA[Conditionally automated vehicles (AVs) allow drivers to divert their attention from the road under specific conditions defined by the Operational Design Domain (ODD) but require drivers to resume manual control when approaching the ODD boundary. In such scheduled takeover scenarios, drivers are afforded more time to restore situation awareness and manage the takeover task at their own pace. This study focuses on a typical ODD exit scenario—freeway exits—and investigates the effectiveness of a multistage takeover request (ToR) design comprising three stages: information, warning, and command. A driving simulator experiment involving 32 participants evaluated how ToR presence (single-stage vs. multistage) and modality (semantic speech, dynamic visuals, or both) affected the takeover process, including takeover strategy, pre-takeover situation awareness, post-takeover vehicle control performance, and subjective evaluations. Results showed that multistage ToR designs significantly improved behavioral performance, including faster eyes-on-road and takeover responses, shorter preparation times, and enhanced perceptual and cognitive preparedness. These designs also enhanced user experience, particularly by increasing trust and reducing mental workload. The performance benefits were most pronounced for female drivers and for those who delayed initiating their takeover response until the command stage. These findings highlight the value of incorporating structured, multimodal ToR designs for scheduled takeover scenarios, and support the development of adaptive systems tailored to individual differences in driver response tyle and characteristics.]]></description>
      <pubDate>Thu, 15 Jan 2026 14:31:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/2642406</guid>
    </item>
    <item>
      <title>Real-Time Risk Lane-Change Intention Recognition Prediction at Freeway Exit Ramps</title>
      <link>https://trid.trb.org/View/2642376</link>
      <description><![CDATA[The impact of drivers' subjective heterogeneity on lane-change (LC) decision-making behavior is essential for identifying drivers' LC intentions and predicting risks more accurately, thereby reducing traffic accidents caused by LC at freeway exit ramps. This study, based on the Next Generation Simulation dataset, considered drivers' risk preference heterogeneity and proposed a research framework that integrated three modules: a risk preference quantification module based on cumulative prospect theory (CPT), a LC intention recognition module (combined the Temporal Convolutional Network, the Long Short-Term Memory, and the self-attention), and a real-time LC risk prediction module based on the Light Gradient Boosting Machine (LightGBM). This approach effectively combined LC intention recognition with real-time risk prediction, improving prediction efficiency and identifying the key features influencing LC risk. Results showed CPT could intuitively describe drivers' risk preferences, transforming previous qualitative descriptions into quantitative analysis. Considering drivers' short-term risk preferences improved the model's intention recognition performance, achieving optimal results with a 2-s time window, where each index reached 95%. The LightGBM real-time risk prediction, based on LC intention recognition, achieved prediction performance of more than 93% for all indices and showed high sensitivity to risky LC behaviors, with prediction accuracy reaching 97%. Feature importance analysis suggested that, for left lane changes, drivers needed to prioritize vehicle speed control. In contrast, for right lane changes, the driver's risk preference was the most critical feature. The proposed framework can offer unique insights for vehicle safety warnings, support autonomous and assisted driving development, and provide theoretical references for traffic education and management.]]></description>
      <pubDate>Thu, 18 Dec 2025 11:53:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/2642376</guid>
    </item>
    <item>
      <title>Impact of traditional traffic control devices on wrong-way driving incidents at interchange off-ramps</title>
      <link>https://trid.trb.org/View/2611676</link>
      <description><![CDATA[Wrong-Way Driving (WWD) poses a significant threat to road safety, as drivers travel in the opposite direction of legal traffic flow, often resulting in severe injuries and fatalities. This study evaluated and summarized traditional low-cost countermeasures to prevent WWD incidents. Data from 406 WWD incidents were analyzed to assess the effectiveness of various countermeasures. The results revealed that the average WWD distance can be reduced by implementing more supplemental Wrong-Way (WW) signs on off-ramps, highlighting the importance of additional visual cues. At least two sets of Traffic Control Devices (TCDs) were found to be necessary to achieve optimal performance in reducing WWD distance and also accommodating 97 % of self-corrected turnaround events. Moreover, the study emphasized the significance of TCD placement, as the average WWD distance increased when TCDs were located farther from off-ramp terminals. Every 10 ft increase in the distance of 1st TCD is expected to increase WWD distance by 3.4 ft. Based on the findings, it is recommended to place the first set of WW-related TCDs within 75 ft of the stop line to enhance their early warning capabilities. The second set of TCDs should be placed 50 ft from the first set, and a gap of 150 ft should be maintained between the second and third sets of TCDs. Additionally, the installation of supplemental WW-related TCDs at high-risk locations was advocated to effectively target areas prone to WWD incidents. By strategically deploying these countermeasures, transportation agencies can take substantial steps toward enhancing roadway safety and reducing the occurrence of WWD.]]></description>
      <pubDate>Thu, 18 Dec 2025 09:38:48 GMT</pubDate>
      <guid>https://trid.trb.org/View/2611676</guid>
    </item>
    <item>
      <title>Guidelines for Applying Managed Lane Strategies to Ramps</title>
      <link>https://trid.trb.org/View/2582255</link>
      <description><![CDATA[Current funding constraints and difficulty in gaining environmental and public approval for large-scale construction projects has forced the Texas Department of Transportation (TxDOT) to continue considering alternative solutions to roadway widening to mitigate congestion. One area for potentially improving freeway performance is ramp locations. Current ramp treatments only address point demand. Applying managed lane operational strategies to ramps could maximize existing capacity, manage demand, offer choices, improve safety, and generate revenue. This project will investigate the application of these demand management strategies to mainlane ramps and managed lane ramp operations during the peak period: i.e., “managed ramps.” Such strategies could include peak-period use of both mainlane or managed lanes entrance and exit ramps by user group, possibly influencing mode choice, enhancing mobility, improving safety in a freeway corridor, and helping ensure the integrity and free-flow operations of a managed lanes facility. This document provides guidance on identifying when to consider managed ramps based on relevant factors including target users in the corridor, congestion level, ramp spacing/density, ramp volumes, accident history, etc.]]></description>
      <pubDate>Sat, 22 Nov 2025 17:17:30 GMT</pubDate>
      <guid>https://trid.trb.org/View/2582255</guid>
    </item>
    <item>
      <title>Traffic Management on an At-Grade Signalized Intersection Connecting to Urban Expressway Ramps</title>
      <link>https://trid.trb.org/View/2203752</link>
      <description><![CDATA[An elevated urban expressway connects to its frontage roads by on/off ramps. Under the expressway, frontage roads, two pairs of on/off ramp terminal and cross streets construct the complex at-grade intersection. One typical complex intersection under the Inner Ring Expressway in Shanghai was selected in this study. The main reason for congestion at this intersection is that traffic movements with different origin-destination (OD) weave within the section from the ramp terminal to the stop-line on the departure legs. To eliminate the weaving operation, lane function was reassigned, and signal timing was redesigned to a five-phase scheme. Simulation tool VISSIM 4.1 was applied to evaluate performance of the new intersection. Simulation results indicated that significant reduction of vehicle delay and queue length in the new scheme.]]></description>
      <pubDate>Wed, 15 Oct 2025 09:36:34 GMT</pubDate>
      <guid>https://trid.trb.org/View/2203752</guid>
    </item>
    <item>
      <title>Development of Improved Guidelines for Frontage Road Driveway Access Location</title>
      <link>https://trid.trb.org/View/2570741</link>
      <description><![CDATA[Access on the frontage road in close proximity to exit ramp terminals can amplify the amount and severity of weaving and lead to operational and safety problems on the frontage road. This report summarizes research activities directed at evaluating the operation of frontage roads with unsignalized marginal access located at varying distances from exit ramp terminal points and developing guidelines for appropriate spacing under these conditions. The basic research approach consisted of: I) analyzing accident data; 2) making field observations to identify distances required to safely make weaving maneuvers; and 3) developing an analytical model to predict the density of the weaving section on the frontage road as a function of frontage road volume, exit ramp volume, total driveway volume, frontage road configuration, and exit ramp to access spacing. The model was developed from the results of a computer simulation (using CORSIM) that was calibrated using field data from several frontage road sites in Texas. Results of the accident and weaving (field observation) analyses were used to develop recommended "minimum" distances between exit ramp terminal points and the nearest frontage road access, while the analytical model was used to develop "desirable" distances.]]></description>
      <pubDate>Tue, 26 Aug 2025 14:34:55 GMT</pubDate>
      <guid>https://trid.trb.org/View/2570741</guid>
    </item>
    <item>
      <title>Heterogeneous and differential treatment effect analysis of safety improvements on freeways using causal inference</title>
      <link>https://trid.trb.org/View/2584311</link>
      <description><![CDATA[Evaluating safety effectiveness of freeway design improvements is crucial for enhancing overall safety and confirming the efficacy of specific measures implemented. Limited research has addressed treatment heterogeneities that influence crash outcomes, and previous studies have often been susceptible to confounding biases, which may distort causal inference results. To mitigate confounding biases and establish reliable causal relationships between crashes and treatment interventions, this study employed a causal forest (CF) model to assess the safety efficacy of freeway exit improvements – including lane control, traffic signs, speed-limit signs, and crash attenuators – on freeways in Suzhou, China. The authors compared naïve and empirical Bayes before-after methods against the Average Treatment Effect (ATE) estimated by the CF approach. Geometric design and traffic operation characteristics were then considered in measuring the Heterogeneous Treatment Effects (HTE) of these improvements, with the aim of identifying road features where treatment benefits were most pronounced. Additionally, a Differential Treatment Effects (DTE) analysis within a causal framework was employed to estimate treatment effects on the residuals, uncovering more intricate and complex causal relationships. The study demonstrated that CF method provides more stable ATE estimates. An analysis of the distribution of the treatment effects revealed a diverse range of impacts, indicating both positive and negative outcomes. Significant variability in treatment effects was evident from heterogeneous testing results. Noteworthy outcomes from treating freeway exits were observed in areas with an Average Annual Daily Traffic (AADT) ranging from 12,000 to 28,000 vehicles per day, average speeds of 95 km/h and above, two or four lanes on each side, and an exit-only ramp configuration. These findings contribute to valuable technical insights for selecting and evaluating safety enhancement strategies on freeways.]]></description>
      <pubDate>Tue, 19 Aug 2025 15:29:43 GMT</pubDate>
      <guid>https://trid.trb.org/View/2584311</guid>
    </item>
    <item>
      <title>Impact of Intelligent Networking on Vehicles Exiting at Urban Intersections</title>
      <link>https://trid.trb.org/View/2407692</link>
      <description><![CDATA[Intelligent network connection was expected to completely break the existing rules and orders of transportation system. The theoretical peak speed of 5G wireless bandwidth could reach more than 10 Gb per second, which enables cars to exchange information such as location, speed, and destination. It would provide a technical basis for real-time information sharing among vehicles. Based on the formal study of Neural Networks, the authors added Gaussian noise in the RBM top-level connecting regression, constructing a CDSHybird model that could predict traffic flow in the urban intersections. The results showed that the model proposed in this paper could reflect the movement of vehicles passing through urban intersections in various situations. Further development of interconnection would probably realize the control of traffic flow without a traffic light, which could maximize the efficiency of traffic.]]></description>
      <pubDate>Mon, 18 Aug 2025 08:51:51 GMT</pubDate>
      <guid>https://trid.trb.org/View/2407692</guid>
    </item>
    <item>
      <title>Compensatory behavior for mental workload induced by freeway destination signs</title>
      <link>https://trid.trb.org/View/2569769</link>
      <description><![CDATA[Exit ramps are accident-prone areas of freeways. One of the reasons for this is the information overload induced by destination signs, which makes them challenging to recognize and may even result in tension or mistakes. This study examined the cognitive workload that destination signs place on drivers and the compensatory behavior they use to counteract the additional workload. Forty-five subjects were recruited to conduct a simulated driving experiment. Four destination signs with varying information levels were used to load mental workload as independent variables. Workload indicators (such as the NASA-TLX questionnaire, heart rate variability and eye movements) and compensatory behavior metrics (such as speed, distance headway, time headway and the increased cognitive time due to deceleration) were collected and analyzed through a mixed design analysis of variance. The results show that destination signs with different levels of information produced various cognitive workloads. Drivers’ subjective workload increased significantly with an increase in sign information; however, the heart rate variability indicators did not significantly differ due to the drivers’ compensatory strategy in the cognition process. The principal compensating strategy found was the longitudinal deceleration; as the speed dropped, the distance headway and time headway were significantly increased. Although professional drivers demonstrated a significantly greater speed differential during deceleration than nonprofessional drivers, the alternative safety indicators did not show statistical differences. Additionally, driving experience had no significant impact on the increased cognitive time of compensatory strategies. On the one hand, the effort invested by drivers increased with the workload. On the other hand, when the workload exceeded a particular degree, compensatory driving behavior was triggered, which in turn reduced the workload. There was no discernible difference in the effectiveness of the compensatory strategies employed by professional drivers and nonprofessional drivers under complex destination signs. The findings could provide safety considerations for the design of traffic signs.]]></description>
      <pubDate>Tue, 29 Jul 2025 13:56:48 GMT</pubDate>
      <guid>https://trid.trb.org/View/2569769</guid>
    </item>
    <item>
      <title>Freeway Frontage Road Operations and Safety Study</title>
      <link>https://trid.trb.org/View/2556677</link>
      <description><![CDATA[This report summarizes the findings of a detailed two-year study of freeway frontage road operations. The objectives of the study were to identify: (1) the safety and operational problems of ramp-frontage road intersection and terminals of one-way frontage roads; (2) the probable effect of conversion from two-way to one-way service road operation; and (3) to suggest warrants for conversion from two-way to one-way frontage road operation. Data were collected at nine frontage road conversion sites, forty-five ramps, including both entrance and exit ramps, and all types of ramps used on two-way and one-way frontage roads. Erratic maneuvers were recorded and accident experience examined statistically. From these data, it was determined that ramp type was not a significant influence on the accident rate. Degree of roadside development and frontage road ADT (total of both frontage roads) were the only statistically significant factors. Two warranting conditions are suggested: (1) Volume Warrant - Rural Area 7500 VPD (total of both frontage roads); Intermediate Area 6000 VPD (total of both frontage roads); and Urban Area 5000 VPD (total of both frontage roads). (2) Accident Experience - 20 accidents/mile, average of three years; 30 accidents/mile in one year. Vehicular delay dominates the benefits and costs analysis.]]></description>
      <pubDate>Sat, 05 Jul 2025 17:02:50 GMT</pubDate>
      <guid>https://trid.trb.org/View/2556677</guid>
    </item>
    <item>
      <title>Increased Capacity of Highways and Arterials Through the Use of Flyovers and Grade Separated Ramps</title>
      <link>https://trid.trb.org/View/2552281</link>
      <description><![CDATA[This study analyzes grade separated ramps serving frontage roads to investigate operational and geometric requirements, to prepare guidelines on benefit and cost analysis and to propose warranting conditions. It has been observed that grade separated ramps can be a cost effective solution to weaving on freeways created by contiguous on- and off-ramps, and for access to and from some high demand points on the frontage road.]]></description>
      <pubDate>Mon, 30 Jun 2025 16:38:30 GMT</pubDate>
      <guid>https://trid.trb.org/View/2552281</guid>
    </item>
    <item>
      <title>Operational and Safety Analysis of Two-Way and One-Way Frontage Roads</title>
      <link>https://trid.trb.org/View/2549166</link>
      <description><![CDATA[This report documents the findings of a detailed study of freeway frontage road operation and safety. Vehicles were video taped during the exit and entry maneuver to and from frontage roads for all types of ramps. Erratic maneuvers were identified and recorded. The master file of the Department of Public Safety accident file was searched and accidents occurring in the ramp areas identified. The report documents the types of erratic maneuvers observed and the recommended treatments to reduce the number of erratic traffic movements in ramp areas. There was no apparent pattern to erratic maneuvers except that slip ramps to one-way frontage roads had the largest percentage of these maneuvers. The accident analysis revealed that ramp type was not a significant contributor to accident experience at the ramp-frontage road intersection. Frontage road ADT and degree of roadside development were found to be significant.]]></description>
      <pubDate>Tue, 24 Jun 2025 17:43:09 GMT</pubDate>
      <guid>https://trid.trb.org/View/2549166</guid>
    </item>
    <item>
      <title>Highway Investigation Report: Collision of Motorcoach with Combination Vehicles Parked Along Exit Ramp to I-70 Rest Area, Highland, Illinois, July 12, 2023</title>
      <link>https://trid.trb.org/View/2566020</link>
      <description><![CDATA[​On Wednesday, July 12, 2023, about 1:48 a.m. central daylight time, a 2014 Prevost 50-passenger motorcoach with 21 occupants was westbound on Interstate 70 (I-70), near Highland, Madison County, Illinois. The motorcoach, owned and operated by Greyhound Lines, Inc., was on a scheduled route from Indianapolis, Indiana, to St. Louis, Missouri. Near the Silver Lake Rest Area, the motorcoach departed I-70 onto the rest area exit ramp, where it collided with three truck-tractor/semitrailer combination vehicles parked on the ramp’s right shoulder. As a result, three motorcoach passengers were fatally injured. The driver and 11 passengers sustained injuries ranging from minor to serious. The three truck drivers, who were inside their vehicles at the time of the crash, were uninjured. The safety issues identified in this investigation are motorcoach driver fatigue; deficient driver oversight by Greyhound, including lack of a progressive discipline policy, lack of adequate record-keeping, and lack of policies for implementing driver monitoring systems; insufficient federal guidance on safety management, driver coaching, and fatigue mitigation; lack of seat belt use by the motorcoach passengers; and crash risk from lack of truck parking availability along the National Highway System. The National Transportation Safety Board (NTSB) makes new recommendations to the US Department of Transportation, the Federal Motor Carrier Safety Administration, Greyhound Lines, Inc., the National Coalition on Truck Parking, the American Bus Association, and the United Motorcoach Association. The NTSB also reiterates a recommendation to the Federal Motor Carrier Safety Administration and reiterates and classifies a recommendation to the Federal Motor Carrier Safety Administration.]]></description>
      <pubDate>Tue, 24 Jun 2025 17:13:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/2566020</guid>
    </item>
    <item>
      <title>Effects of Off-Ramps on Freeway Operation</title>
      <link>https://trid.trb.org/View/2548965</link>
      <description><![CDATA[Studies have indicated that the off-ramp is a critical element of a freeway facility and can contribute significantly to both desirable and undesirable operations. If maximum efficiency is to be obtained from a freeway, the off-ramps must be located, designed, and operated to minimize any adverse effects on main-lane freeway flow and to permit maximum utilization of the facility. The original objectives of the off-ramp project were to evaluate the effect on freeway operation of (1) the frequency of off-ramps and (2) various arrangements of off-ramps. Studies of the off-ramp problem led to the conclusion that the objective of the off-ramp project should be expanded to study the total effect of off-ramps rather than the more narrow scope of considering only frequency and arrangement. Consideration of the problem resulted in the definition of several factors of off-ramp location, design, and operation that could affect the operation of the freeway. These factors are enumerated as follows: (1) deceleration distance, (2) off-ramp capacity, (3) short trip generation, (4) weaving maneuvers, (5) access control, and (6) access provision. Research on the off-ramp project was directed toward an investigation of each of these factors.]]></description>
      <pubDate>Sat, 07 Jun 2025 19:08:09 GMT</pubDate>
      <guid>https://trid.trb.org/View/2548965</guid>
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