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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>
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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>Notification Systems to Enhance Construction Vehicle Safety at Work Zone Access Points</title>
      <link>https://trid.trb.org/View/2712172</link>
      <description><![CDATA[Commercial motor vehicles (CMVs) are consistently overrepresented in fatal work zone crashes. Improving CMV safety in work zones is a priority at federal and state levels. One aspect of particular interest is the interaction between slow-moving construction vehicles, delivering and removing materials from work zones, and traffic in the travel lanes. A sizable portion of rear-end collisions and sideswipe crashes involves construction vehicles exiting or entering travel lanes from the workspace, with speed differentials between through traffic and construction vehicles being a significant factor.

Advanced work zone technologies have the potential to reduce vehicle conflicts between slow-moving construction vehicles entering or exiting work zones and traffic in travel lanes. NCHRP Research Report 1142: Innovative Approaches to Enhancing Safety and Efficiency in Work Zones: A Guide,” documented use of entering/exiting vehicle notification as a work-zone safety application in Minnesota and Pennsylvania, with signs warning drivers of slow-moving construction or emergency vehicles entering or exiting the roadway to reduce crash risk.

Several states have reported plans to use smart work zone truck ingress-egress warning systems but noted inadequate information available regarding effectiveness, as well as issues with equipment availability and frequent malfunctions. In addition, pilot studies have been plagued with system performance issues.

The objective of this research is to conduct a scoping study to: (1) Document the state of knowledge regarding the design, operation, and effectiveness of smart work zone truck ingress-egress warning systems. (2) Identify research needs to fill knowledge gaps. (3) 
Propose a study design for use in potential future National Cooperative Highway Research Program (NCHRP) research to address knowledge gaps, with emphasis on safety performance metrics for the traveling public and construction vehicles.]]></description>
      <pubDate>Tue, 09 Jun 2026 12:49:55 GMT</pubDate>
      <guid>https://trid.trb.org/View/2712172</guid>
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    <item>
      <title>Traffic Flow Impacts of Autonomous Utility Service Vehicles Representing Low-Speed Operation in Urban Networks</title>
      <link>https://trid.trb.org/View/2703798</link>
      <description><![CDATA[Autonomous utility service vehicles (AUSVs) represent a distinct class of automated platforms designed to operate at very low speeds (often around 5–10 km/h) for urban road maintenance tasks, yet their integration in mixed traffic remains poorly understood. This study evaluates the effect of AUSVs through a microscopic simulation using a real-world network modeled on the Pangyo autonomous driving testbed in South Korea. Twelve scenarios (six AUSV speeds, 5–30 km/h, and two traffic volumes, level of service [LOS] C and LOS D) were simulated; LOS C and D were deliberately selected—beyond the typical off-peak LOS A/B context—to empirically identify the demand threshold above which AUSV effects become operationally significant. Performance was assessed across vehicle, lane, link, and network levels using speed, shockwave propagation, time-to-collision (TTC) ratios, and lane-change rates. Results revealed consistent patterns. At the lane level, AUSVs at 5 km/h induced backward-moving queues up to 120 m in length and critical TTC ratios of up to 0.50 under LOS D, while no significant disturbances occurred under LOS C—revealing a critical operational threshold between the two demand regimes. At the link level, speed reductions of ≥20 km/h concentrated on two-lane bottlenecks, where overtaking opportunities were constrained. Network-wide, average speeds increased monotonically with AUSV speed, while lane-change rates peaked at 5 km/h (32.5 events/km under LOS C; 59.1 events/km under LOS D) and declined thereafter. These findings support demand-aware scheduling (off-peak for ≤10 km/h operation), minimum speed thresholds (≈15 km/h), and bottleneck-avoiding routes as practical strategies for sustainable AUSV deployment.]]></description>
      <pubDate>Mon, 18 May 2026 14:04:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/2703798</guid>
    </item>
    <item>
      <title>Machine learning training methods using image generation for detecting illegal sidewalk riding by slow vehicles</title>
      <link>https://trid.trb.org/View/2666941</link>
      <description><![CDATA[This study proposes and evaluates efficient methods for creating training data using image generation and viewpoint transformation. We aim to prevent illegal sidewalk riding by slow vehicles, including small motorized bicycles. The study demonstrates that introducing image completion of vehicle objects to the conventional method using viewpoint transformation enhances its performance, improving the true positive rate by approximately 6.5% compared to the baseline. In addition, the training data created by image completion of the background area demonstrated a 7.3% higher performance in identifying the riding environment and reduced the training data creation time by 64% compared to the conventional method using viewpoint transformation. These results demonstrate the effectiveness of efficient training data creation using image completion. Because a large amount of training data is necessary to achieve high performance in riding environment identification across various environments, this study provides relevant insights to facilitate safe riding support for slow vehicles. Ultimately, the proposed method contributes to the development of robust monitoring systems that can rapidly adapt to new traffic regulations and diverse road conditions, thereby enhancing the safety of pedestrians and riders.]]></description>
      <pubDate>Mon, 11 May 2026 08:50:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/2666941</guid>
    </item>
    <item>
      <title>Vehicles Swarm Intelligence: Cooperation in Both Longitudinal and Lateral Dimensions</title>
      <link>https://trid.trb.org/View/2591815</link>
      <description><![CDATA[Longitudinal-only platooning methods are facing great challenges on running mobility, since they may be impeded by slow-moving vehicles from time to time. To address this issue, this paper proposes a vehicles swarming method coupled both longitudinal and lateral cooperation. The proposed method bears the following contributions: i) enhancing driving mobility by swarming like a bee colony; ii) ensuring the success rate of overtaking; iii) cruising as a string of platoon to preserve sustainability. Evaluations indicate that the proposed method is capable of maneuvering a vehicle swarm to overtake slow-moving vehicles safely and successfully. The proposed method is confirmed to improve running mobility by 12.04%. Swarming safety is ensured by a safe following distance. The proposed method's influence on traffic is limited within five upstream vehicles.]]></description>
      <pubDate>Mon, 03 Nov 2025 16:34:55 GMT</pubDate>
      <guid>https://trid.trb.org/View/2591815</guid>
    </item>
    <item>
      <title>Develop Heavy Duty Intersection Designs with High Performance Graded (HPG) Binder or Suitable Asphalt Mixtures</title>
      <link>https://trid.trb.org/View/2614514</link>
      <description><![CDATA[Current asphalt pavements with traditional asphalt mixes perform well under free flow traffic at regular speed. However, due to the nature of slow-moving or standing traffic, the same pavement structure with the same materials appears to severely rut at intersections. Ruts deeper than 2-inches were observed at multiple highway intersections, including those designed with premium mixes such as Stone-Matrix Asphalt, which result in serious safety concerns during wet weather conditions and costs millions of dollars annually to fix. Pavement designs specifically for slow-moving or standing traffic areas such as intersections, are rarely investigated. With the increasing frequency of extreme weather conditions and increase in truck traffic, there is an urgent need to develop long-lasting asphaltic pavement designs for intersections. The research team will coordinate with the Texas Department of Transportation (TxDOT) to develop heavy duty intersection designs for different traffic levels following the same format of the heavy-duty pavement guidelines (i.e. catalogue design approach), using the Texas Mechanistic-Empirical Asphalt Concrete Pavement Design and Analysis System (TxME) with suitable asphalt mixes and other layer materials designed with the reliable laboratory testing protocols. Furthermore, the research team will identify and construct up to three field test sections for Validation of the new heavy duty intersection design method.]]></description>
      <pubDate>Tue, 28 Oct 2025 10:52:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/2614514</guid>
    </item>
    <item>
      <title>Detection of Dangerously Slow Vehicles on Highway Corridor in a Partially Connected Environment</title>
      <link>https://trid.trb.org/View/2569638</link>
      <description><![CDATA[With the expanding development of C-ITS services and their field implementation, the driving experience is now occurring under a partially connected environment. Whether through embedded smartphones or onboard equipment, vehicles are getting connected and regularly emit high-frequency safety messages (CAM in Europe or BSM in the USA) regarding their status. In this paper, as an alternative to the usual methods that rely on expensive dedicated cameras, the authors explore the potential of passive data resources to feed a slow obstacle detection process performed in near-real time. Contrary to the recent literature focusing on the development of dynamic obstacle detection to expand autonomous skills through expensive dedicated sensors, the authors adopt the road managers’ perspective. The authors assume the existence of a monitoring and management center, potentially decentralized to Road-Side Units, collecting the data stream continuously, analyzing it, and enabling it to broadcast safety warning messages to connected vehicles located immediately upstream of the identified slow obstacle. The two-step methodology is based on (i) an automatic lane change detection process followed by (ii) a weighting process and statistical analysis of the space–time scatter plots generated by detected lane changes over a sliding time window. Simulation-based results highlight that despite a low share of connected vehicles, a stationary obstacle can be detected on average at 3 min, while longer delays (5 min) are required when the obstacle is moving between 30 km/h and 50 km/h. Furthermore, disseminating warning messages upstream can improve safety and traffic performance by up to 10 percent for low traffic conditions.]]></description>
      <pubDate>Fri, 17 Oct 2025 16:38:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/2569638</guid>
    </item>
    <item>
      <title>Decarbonization Potential by Combining Slow Steaming and Wind-Assisted Propulsion Systems: A Case Study of a 6,500 DWT Tanker Operating in Indonesian Waters</title>
      <link>https://trid.trb.org/View/2592184</link>
      <description><![CDATA[This study addresses the growing environmental concerns of climate change, which is exacerbated by rising greenhouse gas emissions, particularly in the transportation sector. Maritime shipping, responsible for approximately 2.89% of global CO₂ emissions, is a key contributor to this issue. The International Maritime Organization (IMO) has set ambitious targets to reduce CO₂ emissions from this sector by 40% by 2030 and 100% by 2050, relative to 2008 levels. In response, this study explores the potential of combining two decarbonization strategies, slow steaming and wind-assisted propulsion systems (WAPS), to reduce emissions from maritime transport. The analysis of a 6500-ton DWT tanker operating around Sumatra Island, Indonesia, from July 21, 2023, to July 20, 2024, shows that slow steaming, reducing speed by up to 1 knot, can lead to up to a 20.1% reduction in fuel consumption and carbon emissions, although this results in increased sailing time. The challenge lies in balancing environmental benefits with operational time efficiency. The integration of WAPS, featuring three 250 m² square wingsails, further reduces emissions by 10.3% by harnessing wind power to assist propulsion, without altering the ship’s schedule. By combining both strategies, the tanker achieves a total emissions reduction of up to 29.7%, while maintaining operational efficiency. This combined approach offers a promising, sustainable solution for decarbonizing maritime transport and significantly reducing emissions without disrupting time-sensitive operations.]]></description>
      <pubDate>Mon, 25 Aug 2025 09:04:31 GMT</pubDate>
      <guid>https://trid.trb.org/View/2592184</guid>
    </item>
    <item>
      <title>How to Reduce the Influence of Special Vehicles on Traffic Flow? A Dogit-Abm Approach</title>
      <link>https://trid.trb.org/View/2512437</link>
      <description><![CDATA[Special vehicles (SVs) are vehicles which conduct tasks such as the maintenance of urban roads and are typically characterized by travelling at a lower speed at a constant rate of speed within the same lane. In order to reduce the influence of SVs, guidance zone is designed and provides traffic guidance suggestions (TGS) for human-driven vehicles (HVs) helping drivers for better decision between car-following (CF) and lane-changing (LC). To verify the effectiveness of TGS, an improved Dogit-agent-based model is established to simulate the captive and not captive choice of CF and LC for different driver types under TGS, and build the rules for mixed traffic flow of SV and HVs. Finally, a numerical simulation with a three-lane system is conducted to analyze the traffic efficiency through a set of indicators, and the results show that the TGS can reduce the influence of SVs on traffic flow in a specific occupancy rates range, increase the cross-section traffic volume by about 5%. The TGS also can increase the average speed of HVs in the lane behind SV by about 5% to 30%, and increase traffic density to 200% on the underutilized lane in the raw space in front of the SV.]]></description>
      <pubDate>Fri, 25 Apr 2025 16:11:51 GMT</pubDate>
      <guid>https://trid.trb.org/View/2512437</guid>
    </item>
    <item>
      <title>Assessment of Pedestrian Safety and Driver Behavior Near AVs</title>
      <link>https://trid.trb.org/View/2531107</link>
      <description><![CDATA[As more automated vehicles enter shared roadways, an essential aspect of automated vehicle (AV) safety is understanding the interactions between these vehicles and other road users. Anecdotal incidents about aggressive following and overtaking behaviors at crosswalks near the Med City Mover (MCM), a low-speed automated shuttle (LSAV) pilot demonstration in Rochester, Minnesota, suggested the need for a scientific study of the behaviors of drivers of manual vehicles near the LSAV. In this report, the research team conducted a series of laboratory and field studies aimed at better understanding the safety relationship between LSAVs and the humans they share the road with. Overall, the studies found an increased risk of overtaking and multiple threat passing near the MCM which may increase the risk of pedestrian-involved crashes, sideswipe crashes, and rear-end crashes. Study findings suggest that poor human-machine interfaces, exceptionally slow vehicle speeds, and resultant large queues behind the MCM contribute to these risks. Improved communication interfaces, speeds more consistent with the surrounding traffic, and smaller queue size are all important factors that AV developers and future pilot demonstrations must to consider to better promote pedestrian safety near AVs.]]></description>
      <pubDate>Mon, 31 Mar 2025 15:17:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/2531107</guid>
    </item>
    <item>
      <title>A Retrograde Vehicle Detection Method Based on the Optical Flow Field</title>
      <link>https://trid.trb.org/View/2203479</link>
      <description><![CDATA[Vehicles generally run at high speeds on the highway, so the presence of retrograde vehicles on the road greatly increases the probability of traffic accidents. In view of this situation, the authors introduce a new macro-method to detect retrograde vehicles based on optical flow.Their approach mainly uses pyramids with the Lucas-Kanade motion estimation method, which greatly reduces computational complexity. Since the flow of traffic is regular and physically measurable, its optical flow field is also orderly and regular, allowing the optical flow vector to accurately reflect the velocity of traffic flow. Experiments show that retrograde vehicles on the highway can be well detected by finding abnormal changes in the optical flow field.]]></description>
      <pubDate>Mon, 17 Jun 2024 14:45:42 GMT</pubDate>
      <guid>https://trid.trb.org/View/2203479</guid>
    </item>
    <item>
      <title>Modeling and Development of Operation Guidelines for Leader-Follower Autonomous Truck-Mounted Attenuator Vehicles</title>
      <link>https://trid.trb.org/View/2361819</link>
      <description><![CDATA[Mobile and slow-moving operations, such as striping, sweeping, bridge flushing and pothole patching, are critical for efficient and safe operation of the highway transportation system. A successfully implemented leader-follower autonomous truck mounted attenuators (ATMA) system will eliminate all injuries to DOT employees in follow truck (FT) provided appropriate Statutory authority. The leader-follower system design imposes more requirements to the lead truck (LT) drivers in order to ensure a safe and smooth system operation. The driver is now required to make driving decisions not only from the lead truck’s perspective, but also consider the potential implications of his decisions to the follow truck. This project aims to develop a set of rules and clear instructions for ATMA system operation.]]></description>
      <pubDate>Wed, 15 May 2024 10:16:07 GMT</pubDate>
      <guid>https://trid.trb.org/View/2361819</guid>
    </item>
    <item>
      <title>Design Technique on Enclosure Openings Using Adjoint Method for Vehicles with Low Ram Pressure</title>
      <link>https://trid.trb.org/View/2320580</link>
      <description><![CDATA[The ram pressure is lower than the total pressure of the cooling fan in stationary or low-speed vehicles, and the heat is typically managed by the speed of the cooling fan or opening the enclosure. However, the long-term noise exposure to the working space can be a problem due to stationary or low speed operation. In this paper, the opening search technique for the enclosure using the adjoint method has been proposed to solve the dilemma between heat management and noise control.]]></description>
      <pubDate>Tue, 27 Feb 2024 16:40:18 GMT</pubDate>
      <guid>https://trid.trb.org/View/2320580</guid>
    </item>
    <item>
      <title>A New Model to Evaluate Percent-Time-Spent-Following on Two-Lane Highways</title>
      <link>https://trid.trb.org/View/1974538</link>
      <description><![CDATA[This paper presents the evaluation of percent-time-spent-following (PTSF), one of the key service measures as indicated by Highway Capacity Manual (HCM) to assess level of service (LOS) under heterogeneous traffic conditions for two-lane highway. The PTSF is defined as “the average percentage of travel time that vehicles must travel in platoons behind slower vehicles because of their inability to pass.” Two-lane highway flow is very different from that of single-lane highways mainly because vehicles oppose traffic in the opposite lane, and as a result, they may be subjected to delaying because of their inability to pass slow-moving vehicles. Detecting from the existing studies, it is declared that measuring PTSF directly in the field is quite tedious. However, Highway Capacity Manual put forward some logical stratagem to evaluate PTSF with the 3 s surrogate measure which overestimated the field results. Because of this difficulty, the evaluation of PTSF has been based on methodical procedure which uses equations obtained from simulations and field examination at given location based on substitute measure, the percent of vehicles traveling with headway less than 3 s. In this study queuing analogy is employed to measure PTSF by measuring the headways inside and outside platoons on the two-lane highways of Himachal (India). In this analysis, middle or average range will be that where number of headways inside and outside the platoon will be equal. The difference in range of PTSF grows as volume increases. The range of PTSF measured is lesser than that accorded in the HCM. The main difference for the range of PTSF between the current study and HCM is that using queuing analogy LOS “A” has a PTSF value less than 16% while for HCM it is 35%. This study also propounds a new method of estimating PTSF which can be used as a powerful tool to provide rational idea of various measures for LOS that would otherwise be very hard to estimate.]]></description>
      <pubDate>Tue, 05 Dec 2023 16:50:29 GMT</pubDate>
      <guid>https://trid.trb.org/View/1974538</guid>
    </item>
    <item>
      <title>How Much Do We Know about Low-Speed Vehicle and Golf Cart Communities and Crashes: A Case Study in Nocatee, Florida</title>
      <link>https://trid.trb.org/View/2194378</link>
      <description><![CDATA[Low Speed Vehicle (LSV)/Golf Cart (GC) communities are those modern residential areas that fully or partially allow LSVs/GCs to travel within the community. Whereas LSV/GC communities are increasing rapidly, the safety impacts of LSV/GC on the community have rarely been investigated. Also, no national uniform manuals are available for guiding the proper design of signs, pavement markings, and signals in the community. In this study, five years (2016–2020) of fatal crash data that involved LSV/GC were extracted from the National Highway Traffic Safety Administration (NHTSA) Fatality Analysis Reporting System (FARS) database to: (1) provide an overview of LSV/GC fatal crashes in the United States, (2) discuss characteristics of LSV/GC fatal crashes, and (3) delineate significant contributing factors. A case study in a large LSV/GC community in Florida was conducted to identify current issues and recommend improvements on: (1) driving behavior of LSV/GC drivers, (2) LSV/GC-related traffic control devices, and (3) LSV/GC community planning. The findings can help national and state agencies make proactive decisions to enhance traffic safety and livability for LSV/GC communities.]]></description>
      <pubDate>Thu, 22 Jun 2023 09:49:09 GMT</pubDate>
      <guid>https://trid.trb.org/View/2194378</guid>
    </item>
    <item>
      <title>Automated Last Mile Connectivity for Vulnerable Road Users – Real-World Low Speed Autonomous Vehicle Deployment</title>
      <link>https://trid.trb.org/View/2114835</link>
      <description><![CDATA[An EasyMile EZ10 low speed autonomous vehicle (LSAV) was deployed on a route between the Virginia Tech Transportation Institute campus and a nearby bus transit stop to study prospective user attitudes and acceptance regarding trust in technology, system safety, and personal security. The LSAV operated on this route within normal travel lanes and interacted with mixed public traffic that included the full range of transportation users from pedestrians to heavy vehicles. The findings of this deployment work are shared in a lesson-learned format in the hope that the knowledge gained through this research and technology deployment will inform future LSAV implementations and provide insights into how automated technologies should be applied and regulated considering real-life usage aspects. This report is one of two produced for the larger study. While this report focuses on the actual deployment of the LSAV, the other focuses on vulnerable road users and their prospective use of this technology.]]></description>
      <pubDate>Mon, 27 Feb 2023 09:33:17 GMT</pubDate>
      <guid>https://trid.trb.org/View/2114835</guid>
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