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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>
      <url>https://trid.trb.org/Images/PageHeader-wTitle.jpg</url>
      <link>https://trid.trb.org/</link>
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    <item>
      <title>Safety at Minor Intersections along Highways with Roadside Developments: A Case Study in Indian Context</title>
      <link>https://trid.trb.org/View/2659335</link>
      <description><![CDATA[The present paper reports an investigation on the safety deficiencies at minor investigation and identifying the crash potentials using surrogate safety measures on a typical Indian Highway having roadside developments. Intersections along the highways are one of the high risk locations for road crashes due to more number of conflicts. A safety audit of six representative minor intersections, both 3-legged and 4-legged, revealed that there are significant deficiencies at those locations. Crash potentials are estimated in terms of Post Encroachment Time for cross and rear-end collisions from manual and videography traffic survey data, which indicated that the number of critical conflicts are significantly high particularly for Vulnerable Road Users. Also more number of critical conflicts occur when major road vehicle is a 2-Wheeler. This necessitates the adoption of suitable safety treatments at/near the intersections. The methodology is beneficial in assessing the crash potentials of other intersections in developing countries context.]]></description>
      <pubDate>Mon, 23 Mar 2026 15:20:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/2659335</guid>
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    <item>
      <title>Introducing the concept of alternative intersections with three-phase traffic signals</title>
      <link>https://trid.trb.org/View/2502118</link>
      <description><![CDATA[At intersections where traffic demand is above capacity, reducing the number of signal phases may help operational performance. Alternative intersections may help achieve the reduction; however, retrofits to alternatives with two-phase signals may be impactful and unpopular. The authors' study evaluates five alternative signalized intersections with three critical phases, namely partial median U-turn intersection (MUT), partial continuous-flow intersection (CFI), a combination of MUT and CFI (MUT/CFI combo), reverse reduced conflict intersection (reverse RCI), and thru-cut. Three-phase designs may provide better capacity than conventional intersections with fewer impacts than two-phase intersections and, therefore, may be more palatable to stakeholders. A wide range of simulation scenarios were tested to evaluate the performance of the intersections using VISSIM and the Surrogate Safety Assessment Model. Based on the results, all three-phase designs outperformed the conventional design in terms of traffic operation. The partial CFI and MUT/CFI combo yielded the fewest conflicts among the designs evaluated.]]></description>
      <pubDate>Fri, 21 Feb 2025 17:08:04 GMT</pubDate>
      <guid>https://trid.trb.org/View/2502118</guid>
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    <item>
      <title>Special Crash Investigations: On-Site Driver Air Bag Inflator Rupture Investigation; Vehicle: 2010 Ford Fusion; Location: Florida; Crash Date: June 2021</title>
      <link>https://trid.trb.org/View/2342166</link>
      <description><![CDATA[This report documents the on-site investigation of a crash involving a 2010 Ford Fusion and a 2001 Dodge Ram in which the Ford driver’s frontal air bag inflator ruptured, resulting in a severe laceration to the abdomen of the unbelted 52-year-old male driver. The crash occurred in the right lane of a 10-lane, divided State highway at a 3-leg intersection that included a driveway to a shopping plaza. The Dodge was driven by a belted 56-year-old male and occupied by a belted 56-year-old female in the right front seat. According to the police crash report, the Ford driver stated he was traveling west and changing lanes from the right-through-lane to the right-turn-lane, adjacent to the curb. Meanwhile, the Dodge was initially traveling south on the shopping plaza driveway that connected to the State highway and turning right onto the westbound roadway. The front plane of the Ford struck the left plane of the Dodge. This impact resulted in deployment of the Ford’s driver’s frontal air bag. During the deployment, the backside of the inflator ruptured. A fragment of the inflator was projected down and rearward, lacerating the driver in the abdomen. He was transported to a level II trauma center where he was hospitalized for two days. The Dodge driver did not sustain any police-reported injury.]]></description>
      <pubDate>Thu, 22 Feb 2024 09:27:33 GMT</pubDate>
      <guid>https://trid.trb.org/View/2342166</guid>
    </item>
    <item>
      <title>Can turbo-roundabouts and restricted crossing U-Turn be effective solutions for urban three-leg intersections?</title>
      <link>https://trid.trb.org/View/2188331</link>
      <description><![CDATA[This research explored the potential of replacing conventional single-lane roundabouts by turbo-roundabouts and yield- and stop-controlled restricted crossing U-Turn (RCUT) at intersections located in urban corridors. A simulation approach based on a well-integrated assessment of traffic performance, emissions and driving volatility indicators of alternative intersection designs (AIDs) is therefore a major contribution of the study. The paper also addressed the impacts that several locations of the U-Turn crossovers have on travel and idling times, as well as on carbon dioxide and nitrogen oxides emissions. Traffic, pedestrian, and cyclist flow data were collected from two urban three-leg single-lane roundabouts. A microscopic simulation platform of traffic and emissions (respectively, VISSIM and vehicle specific power) was used to evaluate intersection-specific design and operations. The results indicated that turbo-roundabout and yield-controlled RCUT outperformed the existing single-lane roundabout at the two sites. Turbo-roundabout generally yielded the lowest travel times and emissions compared to the other intersections. The Yield-RCUT also performed better than the single-lane roundabout for U-Turn crossover located 100–170 m from the main intersection. These findings bring a solid basis for academic research and transportation planners to promptly consider the implementation of AIDs and contribute to sustainable mobility in cities.]]></description>
      <pubDate>Mon, 17 Jul 2023 14:44:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/2188331</guid>
    </item>
    <item>
      <title>Joint Confidence Region Approach to Ranking Hotspot Locations Considering Uncertainty in Expected Risk Estimates</title>
      <link>https://trid.trb.org/View/2194353</link>
      <description><![CDATA[Network screening or crash hotspot identification is an essential task of all road safety improvement programs. The most common approach to network screening is to use statistical models to predict the expected risk at the locations of interest and then rank them accordingly. The predicted risk used for ranking is mostly in the form of point estimates, without any consideration of the inherent uncertainty with the estimates, which could lead to identifying a wrong list of crash hotspots. This study aims to fill this research gap by employing a frequentist approach to finding a joint confidence region of risk for ranking locations and identification of hotspots. A case study on three-legged minor approach stop-controlled intersections in Kitchener, Ontario, is conducted to illustrate the proposed approach. Crash risk is modeled using a combination of a hierarchical full Bayesian negative binomial model and a multinomial logit model, which are then used to estimate the 95% confidence interval of the expected risk. For each location, the confidence region of rankings is obtained on the basis of the expected risk estimates. The results show that considering uncertainty in the crash hotspot identification process can lead to varied ranking positions for each location. In fact, considering uncertainty, the true value of the estimated crash risk is unknown. By quantifying uncertainty, it can be concluded that the true value of the estimated risk follows a distribution with different probabilities. As a result, consideration of uncertainty in the road safety analysis may help to identify hotspots more accurately.]]></description>
      <pubDate>Fri, 09 Jun 2023 09:24:32 GMT</pubDate>
      <guid>https://trid.trb.org/View/2194353</guid>
    </item>
    <item>
      <title>Driver’s Risk Compelling Behavior for Crossing Conflict Area at Three-Legged Uncontrolled Intersection</title>
      <link>https://trid.trb.org/View/2113703</link>
      <description><![CDATA[Accidents on the junction of the rural highway have a high percentage compared to straight aligned roads. In this paper, the three-legged intersection on the highway has been analyzed based on classified traffic volume, gap acceptance parameter occupancy time, and road geometric features. The data set for two similar sections of state highway is considered. The value of the critical gap is estimated to understand the driver’s aggressiveness for the different vehicle types and geometric characteristics. The chances of accidents for heavy vehicles are less as compared to two-wheelers and four-wheelers as the critical gap and occupancy time for large vehicles are more. However, the speed of heavy vehicles like LCV, bus-truck decreases on turning movement, which reduces the severity of the accident. Nevertheless, the accident rate at the junction is higher due to other vehicle types as the driver tends to cross the conflict area as a priority. The driver’s aggressiveness and tendency to accept a small gap at the conflicting stream results in crashes. Therefore, at the right turning movements (as the left turn is free in developing countries) of vehicles from the major and minor road are considered and concluded that at T-intersection of highways surrogate safety measure is required based on standard guidelines which need to be focused.]]></description>
      <pubDate>Wed, 31 May 2023 10:54:36 GMT</pubDate>
      <guid>https://trid.trb.org/View/2113703</guid>
    </item>
    <item>
      <title>Modeling Phase Changing Behavior of Traffic Constables at Manually Controlled Intersection—A Case Study in India</title>
      <link>https://trid.trb.org/View/2113320</link>
      <description><![CDATA[The functioning of a manually controlled intersection is primarily based on intermittent stopping and allowance of vehicles to clear the intersection through various streams  by the constable on duty. Unlike pretimed signalized intersections where phase times are fixed, traffic constables decide the phase times at manually controlled intersections in real time. After the initiation of green time of a particular phase, the traffic constable chooses when to change the phase based on the existing traffic scenario. This phase changing behavior of traffic constables can be considered as a binary choice, because he/she has to decide, at a particular time instant, whether or not to change the current phase and switch to the next one. A three-legged manually controlled intersection in Barasat, West Bengal had been considered in this study as the case study intersection. Binary logistic regression was used to model the phase changing decisions made by traffic constables. This was followed by estimation of critical phase times which reflect the optimum time after which the traffic constable wishes to change the phase. The critical phase times of primary, secondary and tertiary phases were found to be 107 s, 34 s and 22 s, respectively. Calculating critical pahse times will help traffic engineers in determining the capacity of manually controlled intersections.]]></description>
      <pubDate>Tue, 28 Mar 2023 09:56:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/2113320</guid>
    </item>
    <item>
      <title>Localizing safety performance functions for two-way STOP-controlled (TWST) three-leg intersections on rural two-lane two-way (TLTW) roadways in Alabama: A geospatial modeling approach with clustering analysis</title>
      <link>https://trid.trb.org/View/2065710</link>
      <description><![CDATA[Safety Performance Functions (SPFs) can be used to predict the number of crashes for highway facilities by site characteristics, including traffic exposures and other specific site factors. The traditional approach to developing SPFs relies on factors that are observed in the data and has an unstated assumption that the relationships between safety performance and observed factors are stationary. However, there might be factors that are not captured by the data but also have significant impacts on roadway safety performance. These factors can lead to significant unobserved heterogeneity in safety performance at different sites. Failure to capture such unobserved heterogeneity in developing SPFs may result in biases and decrease the predictive accuracy. Given the interactions between highway traffic and roadway environments, the unobserved heterogeneity is likely related to the geographic space of the highway network. This study employs a spatial modeling approach, namely Geographically Weighted Negative Binomial Regression (GWNBR), to incorporate spatial heterogeneity into SPF model estimation. The GWNBR model can generate a local SPF for every site instead of a global SPF for one entire jurisdiction (e.g., a state) from the traditional approach. Local SPFs (or l-SPFs) are high-resolution and may be difficult for practitioners to use. To support the implementation of l-SPFs, this study proposes a method to aggregate l-SPFs to various geographic levels. This study first uses the 2014–2018 geo-referenced crash data from Alabama to develop l-SPFs for two-way STOP-controlled (TWST) three-leg intersections on rural two-lane two-way (TLTW) roadways in the state. The results show that l-SPFs vary substantially across Alabama. For example, the coefficients of traffic volume (AADT) on major roads range from 0.126 to 1.203 across different areas of the state. Then, an aggregation method based on K-means clustering is demonstrated to aggregate l-SPFs to various geographic levels of interest. The l-SPFs and their aggregation provide geographic flexibility in developing countermeasures and allocating funds to improve traffic safety considering local conditions.]]></description>
      <pubDate>Tue, 29 Nov 2022 09:29:18 GMT</pubDate>
      <guid>https://trid.trb.org/View/2065710</guid>
    </item>
    <item>
      <title>Gap Acceptance at Non–Standard Unsignalised Intersections</title>
      <link>https://trid.trb.org/View/2059145</link>
      <description><![CDATA[Non-standard unsignalised intersections are very common in European countries with old street networks. The major road often bends at an angle at the centre of an intersection, which makes the intersection non-standard. There are very few papers about the capacity analysis and headway values at these intersections, even though non-standard intersections are widespread not only in Europe but also in the rest of the world. Regarding the fact that priority at the non-standard unsignalised intersection (NSUI) differs from the standard unsignalised intersection (SUI) and the conflict flows, it can be expected that headways are not the same as those at the SUI. Consequently, the capacity at the NSUI differs from that at the SUI. This paper gives critical headway and follow-up headway values at 3-leg and 4-leg NSUI collected by on-field measurement. Recommendations for the values used for the capacity analysis are given, and recommended values are compared at SUI and NSUI.]]></description>
      <pubDate>Fri, 18 Nov 2022 15:37:54 GMT</pubDate>
      <guid>https://trid.trb.org/View/2059145</guid>
    </item>
    <item>
      <title>Safety Performance of Rural Curved Corner Intersections with Regional Effects</title>
      <link>https://trid.trb.org/View/1880164</link>
      <description><![CDATA[This study evaluates the intersection of rural roads where a curved roadway segment connects the major flow of through traffic from orthogonal directions. A system of up to three intersections in combination can be represented singly by the situation modeled in this paper as a curved corner intersection site. This paper evaluates the application of random intercept negative binomial (NB) regression modeling to produce safety performance functions, and compares the outcome with NB models using fixed regional effects. At curved corner intersections, installing a combined/merged intersection approach near the midpoint of the curve is a potential countermeasure that by comparison with three-leg configurations experienced 20% fewer intersection crashes. A larger radius of curvature along the curved segment at these types of intersections is also very favorable for safety performance. Each 100?ft increase in the radius of a three-leg or four-leg curved corner intersection is estimated to reduce total non-animal crash occurrence by 5% and 7%, respectively. This study can help safety engineers to prioritize the improvement of rural un-signalized intersections.]]></description>
      <pubDate>Mon, 27 Sep 2021 18:21:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/1880164</guid>
    </item>
    <item>
      <title>Improved Prediction Models for Crash Types and Crash Severities</title>
      <link>https://trid.trb.org/View/1850198</link>
      <description><![CDATA[This report describes efforts to develop improved crash prediction methods for crash type and severity for the three facility types covered in the 2010 Highway Safety Manual (HSM)—specifically, two‐lane rural highways, multilane rural highways, and urban/suburban arterials. For each, models were estimated for undivided and divided (multilane rural and urban/suburban only) segments and three‐ and four‐leg stop-controlled intersections and four‐leg signal‐controlled intersections (also three‐leg signal‐controlled intersections for urban/suburban arterials). The models use data for segments and intersections with “base conditions” that are defined specifically for each facility type. Only the observations that satisfy the defined base conditions were used for estimating these models. For urban/suburban arterial segments, because no sites met all base conditions for roadside fixed objects and median width, these variables were included in the models only if considered appropriate for that crash type and if the variable was statistically significant in the model and with the expected direction of effect. For some crash types, the number of driveways was also directly included in the models where warranted. These base condition models provide predictions that can be adjusted for actual conditions at a place of prediction, such as lane and shoulder width, the presence of lighting, and other pertinent factors. Content describing these models and instructions for applying them has been prepared for inclusion in the second edition of the HSM. A revisit of the HSM’s procedure for calibrating prediction models for transfer to other jurisdictions is also described and recommendations for updating that procedure offered. Average condition models were also estimated using all available valid data points available from the state data used for each facility type; these are provided in an appendix.]]></description>
      <pubDate>Sun, 16 May 2021 16:57:41 GMT</pubDate>
      <guid>https://trid.trb.org/View/1850198</guid>
    </item>
    <item>
      <title>Safety analysis of unsignalized intersections: a bivariate extreme value approach</title>
      <link>https://trid.trb.org/View/1841069</link>
      <description><![CDATA[Application of extreme value theory (EVT) to road safety analysis is gaining interest, thanks to its ability to produce quick and reliable safety evaluations without the use of crash data. Traditionally applied to single collision types and single extreme variables (i.e. surrogate measures of safety), EVT can be further exploited to simultaneously model multiple collision types, with the use of multiple extreme variables. In this paper two bivariate EVT approaches are applied for the safety evaluation of a three-leg unsignalized intersection, considering: (i) two conflict points and a single surrogate measure of safety; (ii) two surrogate measures of safety collected in a single conflict point. Each bivariate analysis was applied with two EVT methods: Component-wise Maxima (CM) and Excesses Over a Threshold (EOT). Bivariate models produced good results, especially with the EOT method, and were able to significantly improve the univariate benchmark results when the two estimation datasets were correlated.]]></description>
      <pubDate>Fri, 30 Apr 2021 17:10:06 GMT</pubDate>
      <guid>https://trid.trb.org/View/1841069</guid>
    </item>
    <item>
      <title>Effects of Pedestrian Crossing on Minor Road Capacity at Two-Way Stop-Controlled Intersections</title>
      <link>https://trid.trb.org/View/1845021</link>
      <description><![CDATA[Two-way stop-controlled (TWSC) intersections have been used extensively in the United States and other parts of the world when traffic signal control is not warranted. However, it was found that when a major road vehicle yields to crossing pedestrians, minor road traffic could use this extra gap, which tends to improve the capacity of some minor vehicle movements. The current capacity modeling methods did not take into account the effects of the pedestrian crossing on minor road capacity. This paper proposes an analytical model to quantify the increased capacity of minor street movements contributed by minor street pedestrian crossings and validates the model using both field data collected at a three-leg TWSC intersection and through the stochastic simulation method. A sensitivity analysis was performed to reveal the impacts of various factors on minor road capacity. In general, it was found that minor road left-turn capacity at the study intersection was positively correlated to pedestrian crossing volume, yielding rate, and pedestrian crossing time. Besides, modeling results showed that under relatively heavier conflict traffic volume conditions, the effect of the pedestrian crossing on increased capacity on the minor road was more significant.]]></description>
      <pubDate>Wed, 28 Apr 2021 09:28:37 GMT</pubDate>
      <guid>https://trid.trb.org/View/1845021</guid>
    </item>
    <item>
      <title>Intersection Crash Prediction Methods for the Highway Safety Manual</title>
      <link>https://trid.trb.org/View/1847942</link>
      <description><![CDATA[The first edition of the Highway Safety Manual (HSM) included safety performance functions (SPFs) for roadway segments and intersections. However, not all intersection types are covered in the first edition of the HSM. This research was conducted to develop SPFs for new intersection configurations and traffic control types not covered in the first edition of the HSM, for consideration in the second edition of the HSM. Based on input received through a survey of state and local agencies as well as the research project panel, SPFs were developed for the following general intersection configurations and traffic control types: Rural and urban all-way stop-controlled intersections; Rural three-leg intersections with signal control; Intersections on high-speed urban and suburban arterials (i.e., roadways with speed limits greater than or equal to 50 mph); Urban five-leg intersections with signal control; Three-leg intersections where the through movements make turning maneuvers at the intersections; Crossroad ramp terminals at single-point diamond interchanges; and Crossroad ramp terminals at tight diamond interchanges. The research team coordinated with several state agencies to locate candidate intersections for use in developing the SPFs. Site characteristic data were collected for all candidate intersections to select a final list of sites for model development. In addition, crash and traffic volume data were assembled for model development.]]></description>
      <pubDate>Sun, 25 Apr 2021 16:51:35 GMT</pubDate>
      <guid>https://trid.trb.org/View/1847942</guid>
    </item>
    <item>
      <title>Analysis of the Effect of Directional Traffic Volume and Mix on Road Traffic Crashes at Three-legged Unsignalized Intersections</title>
      <link>https://trid.trb.org/View/1768431</link>
      <description><![CDATA[Traffic volume is the most common factor associated with road traffic crash frequency. Use of aggregate volume measures may lead to biased prediction of crash frequencies. Disaggregate analysis that involve hourly volumes can better explain this effect. In low and middle-income countries traffic mix may vary with respect to direction of travel on a road and such variation in proportion leads to crashes and conflicts among crossing vehicles at unsignalized intersections. This paper aims to explore the above relationship in the context of three-leg unsignalized intersections in Malaysia. First exploratory analysis of geometric and traffic variables was performed and their relationship with the crash frequency and type of conflicts was examined. Then probability of crashes was calculated with respect to the percentage of motorcycles that moved in a certain direction and proportion between volume in each direction. Segregation of the data with respect to traffic direction and traffic mix indicated that sites with less percentage of motorcycles moving in the far side direction experienced more crashes as compared to sites with greater percentage of motorcycles moving in the far side direction, given the condition that the volume ratio between each direction was larger than one. Results showed that the chances of crashes and serious conflicts increased upto 25% and 67% respectively; as the percentage of motorcycles that moved in the far side direction decreased from 31%, subject to the condition that the ratio of volume between each direction remained greater than one. It was concluded that traffic mix and traffic volume together influence the crash frequency at unsignalized intersections.]]></description>
      <pubDate>Mon, 22 Mar 2021 10:34:49 GMT</pubDate>
      <guid>https://trid.trb.org/View/1768431</guid>
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