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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>
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    <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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      <title>Single-vehicle injury crashes on rural roads in Iceland: contribution of unforgiving roadsides to fatal and serious injuries of vehicle occupants</title>
      <link>https://trid.trb.org/View/2509352</link>
      <description><![CDATA[About 50% of the most severe crashes on rural roads in Iceland are run-off-road crashes. Many existing roads were designed before the concept of forgiving roadsides became prevailing in road design in Iceland. This research aimed to find the roadside elements that significantly increase the probability of high severity of single-vehicle injury crashes compared to low severity crashes on rural roads to prioritize safety improvements under limited budgets. In this research, 712 police records on single-vehicle injury crashes on rural state roads in Iceland in 2016–2018 were investigated. Crash data developed from police reports do not typically include information on roadside elements even though such information is often visible in photographs or written in words by police officers in their crash reports. This limits research on roadside elements and unforgiving roadsides. In this study, the original written police reports and crash photographs were reviewed. Based on this, additional data regarding the roadside elements were coded and added to the standard crash data. A binary logit model for the most severe injury in each crash was developed to statistically test the effect of roadside elements on the probability of fatal and serious injury versus low severity. The model results showed that two roadside elements, rocks and steep transverse slopes (e.g. where an access road enters a main road), hit by a vehicle in a run-off-road crash, more than doubled the probability of high severity. Road safety measures where roadside rocks are removed or steep transverse slopes are reduced, thereby making roadsides more smooth and forgiving, can be especially beneficial for safety because road users are unlikely to adapt their behavior to increased safety from such improvements. This is because such improvements are likely not easily noticed by road users; hence they reduce the probability of compensatory behavior such as increased driving speed, which could outweigh the safety benefits. The results revealed other contributing factors which more than double the probability of high severity of single-vehicle injury crashes on rural roads. Driver intoxication had the strongest effect, a problem which interestingly was limited to drivers living in Iceland. Not a single foreign tourist driver in this data was noted as being under the influence of alcohol or illegal drugs. To strengthen the analysis of the contribution of roadside elements to the severity of run-off-road crashes and to monitor the effects of improvements in the future, it is recommended that additional information on roadside elements be coded and added to the standard police record crash data.]]></description>
      <pubDate>Thu, 06 Mar 2025 11:34:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/2509352</guid>
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    <item>
      <title>Limited Roadside Visibility: Analysis &amp; Effects</title>
      <link>https://trid.trb.org/View/2444907</link>
      <description><![CDATA[Run-off-road collisions are going unnoticed, obscured from the view of passersby due to factors such as steep roadside slopes, bodies of water, and dense foliage. Consequently, road-users are disappearing, perishing, and first responders are being misplaced or are unable to act. Current literature does not address the hazard of concealability of ROR collisions within limited roadside visibility areas, and the extent of its impact, by nature, cannot be fully know  A case study of a North Saanich couple who were reported missing in August of 2019 is explored. Tragically, the couple was found deceased forty feet from the highway down a steep embankment and just out of sight from their families and the police officers who drove past them. Through analyzing the design elements and topography of a roadside’s cross section, this study demonstrates which run-off-road collisions may become hidden, and where. A map of such locations can then be compiled to assist authorities, Search & Rescue operations, and families in locating victims of this hazard, as well as to quantify the scope of the associated risk.  This research finds that, due to many factors, run-off-road collisions are easily concealable, and the number of these locations is significant. Not only are lives being lost unnecessarily, but the cost to communities is substantial.  When locations with limited roadside visibility are charted, search parties are provided a strategic vantage point for rescue and recovery, cost estimates of future roadside safety treatments capable of collision detection are more accurately derived, and first responders are enabled to act in a more efficient manner. This approach can help mitigate the severity of roadside collisions, save lives, protect the environment, and significantly reduce the cost of ROR collisions to communities.]]></description>
      <pubDate>Wed, 08 Jan 2025 13:52:31 GMT</pubDate>
      <guid>https://trid.trb.org/View/2444907</guid>
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    <item>
      <title>Factors associated with single-vehicle crash occurrences on Indonesian toll roads</title>
      <link>https://trid.trb.org/View/2431467</link>
      <description><![CDATA[Crashes on toll roads can be extremely hazardous, resulting in fatalities and serious injuries due to high speeds. Although multi-vehicle crashes are more commonly observed on Indonesian toll roads, single-vehicle (run-off-road) crashes should not be disregarded, as they also pose a significant risk of fatality. To identify the factors contributing to the occurrence of single-vehicle crashes on Indonesian toll roads, this study developed a crash prediction model that incorporates both geometric and traffic characteristics of toll roads, using a Negative Binomial regression model. The results indicate that higher average daily traffic, segments without roadside crash barrier, and segments with median concrete barrier are associated with a higher frequency of single-vehicle crashes. Conversely, the presence of a nearby ramp, bridge pillars, and segments with rigid pavement are associated with a lower frequency of single-vehicle crashes.]]></description>
      <pubDate>Tue, 17 Sep 2024 14:48:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/2431467</guid>
    </item>
    <item>
      <title>Lane keep assist aystems for light vehicles: an Australian evaluation</title>
      <link>https://trid.trb.org/View/2431447</link>
      <description><![CDATA[Lane departure crashes on high-speed rural roads in Australia account for 42 percent of fatal crashes involving light vehicles. To assess the potential road safety benefits of active lane keep assist systems (LKAS) in Australian light passenger vehicles, a study was conducted using induced exposure methods applied to crashes in Australia’s five largest states from 2013 to 2019. Target crashes for LKAS were lane departure related crashes in speed zones of >70km/h on sealed roads. The analysis estimated LKAS was associated with statistically significant reductions of 22 percent and 16 percent for serious casualty and all casualty target crashes, respectively. If all Australian light vehicles were fitted with LKAS, overall reductions in crashes involving light vehicles of 1.76 percent for all casualty crashes, 3.46 percent for serious injury crashes and 9.09 percent for fatal crashes were estimated. These estimates may be conservative as not all vehicles equipped with LKAS could be identified in the data.]]></description>
      <pubDate>Tue, 17 Sep 2024 14:48:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/2431447</guid>
    </item>
    <item>
      <title>TAC clients’ injury severity and safe system road infrastructure program</title>
      <link>https://trid.trb.org/View/2431431</link>
      <description><![CDATA[The severity of injury sustained in road crashes by clients of Victoria’s Transport Accident Commission (TAC) was examined before and after safety barriers were delivered by the Department of Transport and Planning under the TAC-funded Safe System Road Infrastructure Program (SSRIP). Among vehicle occupants in run-off road and head-on crashes, yearly rates of fatalities and claims were calculated in the periods before and after barrier installation for the ‘Top 20’ project routes. Results showed major reductions in severe injury outcomes (77% fewer fatalities, 94% fewer MAIS 3+ serious injury claims) and 74 percent fewer hospital bed days occupied, when comparing the pre and post periods. Percentage reductions were greatest for severe injury outcomes but were observed across all injury severity levels. A small number of residual severe injury cases were identified, highlighting areas for further prevention efforts.]]></description>
      <pubDate>Tue, 17 Sep 2024 14:47:42 GMT</pubDate>
      <guid>https://trid.trb.org/View/2431431</guid>
    </item>
    <item>
      <title>Addressing road and safety barriers at bridge approaches: 2019–2020</title>
      <link>https://trid.trb.org/View/2189281</link>
      <description><![CDATA[The Department of Transport and Main Roads (TMR) has a responsibility to manage safety risks on the network. Roadside safety barriers and terminal treatments are part of the safer roads component. An important contribution in reducing the number of vehicles departing the roadway behind a bridge or culvert approach on Queensland roads is to investigate the feasibility of prompting the provision of additional guardrail length at the approach of the structure itself. Guidance to undertake this investigation is not available as the Austroads and TMR hazard assessment guidance does not provide guidance specific to assessing a hazard behind a bridge approach, nor guidance to design a safety barrier to be placed on a bridge approach to protect an errant vehicle from a hazard. This research project has developed technical guidance that allows practitioners to: identify and evaluate the risk behind a bridge approach; and identify the required safety barrier length to be placed on the bridge approach. This publication will assist practitioners to adopt a risk based approach to identify the need for barriers on bridge approaches whilst using national best practice. The technical guidance provides two examples to guide practitioners through the modified Combined Risk Score calculation process and modified safety barrier length of need calculation using the run-out length method required for assessing hazards behind a bridge approach.]]></description>
      <pubDate>Thu, 01 Jun 2023 14:55:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/2189281</guid>
    </item>
    <item>
      <title>Run-off road crashes in Australia, 2016-2020</title>
      <link>https://trid.trb.org/View/2035921</link>
      <description><![CDATA[This Information Sheet provides descriptive analysis of run-off road (RoR) crashes and compares these with other types of crashes in Australia. Between 2016 to 2020, the average annual number of road deaths in Australia was 1,187. Deaths from run-off road crashes averaged 458 deaths per year. Run-off road crashes accounted for 20 per cent of all crashes and a significantly higher 39 per cent of all fatal crashes in Australia during the five-year period 2016 to 2020. Run-off road crashes form an important focus area in not only reducing total numbers of crashes but also the severity level of crashes.]]></description>
      <pubDate>Thu, 06 Oct 2022 13:56:04 GMT</pubDate>
      <guid>https://trid.trb.org/View/2035921</guid>
    </item>
    <item>
      <title>Modelling driver behaviour in run-off-road crashes : applications in safety system development and safety benefit estimation</title>
      <link>https://trid.trb.org/View/1652316</link>
      <description><![CDATA[Run-off-road crashes have been identified as a major concern for automobile safety and several advanced driver assistance systems (ADASs) targeting run-off-road crashes are on the market today. Assessment of ADASs require relevant test scenarios and valid computational models of driver behaviour. Therefore, the objectives of this thesis has been: (A) define run-off-road test scenarios, and (B) identify a conceptual framework suitable for modelling relevant behavioural mechanisms for crash causation. Cluster analysis was applied to run-off-road crashes from representative in-depth crash data from the German GIDAS database. Nine different clusters were identified, forming a basis for test scenarios. The two largest clusters included crashes relevant for current lane support ADASs (i.e. drift during daytime/night-time), while other clusters suggested that drivers may need support in judging the physical limits of the vehicle (e.g. on snowy rural roads). However, a need for more detailed driver behaviour data was identified. Indeed, naturalistic data, which include more information about driver behaviour in critical situations, may help the definition of test scenarios by linking them to the behavioural mechanisms contributing to the crash causation. This thesis also shows that modelling of driver behaviour may be supported by a framework based on new findings in contemporary neurocognitive science and, specifically, on predictive processing. This new framework improved the interpretation of the clusters and facilitated the formulation of plausible behavioural mechanisms leading to run-off-road crashes.]]></description>
      <pubDate>Tue, 17 Sep 2019 10:33:13 GMT</pubDate>
      <guid>https://trid.trb.org/View/1652316</guid>
    </item>
    <item>
      <title>Definition of a safe barrier for motorcyclists</title>
      <link>https://trid.trb.org/View/1511502</link>
      <description><![CDATA[The paper presents the final report from a literature review including global research, studies and statistics and a workshop with participants from different areas in Sweden, Norway and the European Union Road Federation (ERF). The best barrier for a motorcyclist is no barrier at all. If the barrier itself is more dangerous than what it is designed to protect, no guard rail should be installed. Since there are bridges, trees, steep mountain roads, oncoming traffic and other obstacles in the road environment, there will always be a need of barriers to protect the road users on roads and bridges. But a barrier is never safe, only less dangerous that the risk behind the barrier. According to all tests carried out, barriers with Motorcycle Protection System (MPS) give the lowest risk of injury, whether the rider slides into the barrier or is sitting on the motorcycle. In a collision where the rider is sitting, sharp edges and corners as well as posts sticking up over the barrier have a major significance for the outcome of injuries. Most studies show a lower risk of injury for collisions with concrete barriers compared to the W-profile and cable barriers, some displays of comparable severity. Guardrails with unprotected posts and protruding parts lead to the most serious injuries. Smooth barriers without unprotected posts, provide less risk of injury. Several studies have excluded accidents with cable barriers because of the low number of accidents. The risk of injury in collisions with cable barriers was higher than all other barrier types in some studies, while the risk of injury corresponded to a collision with W-profile in a few studies. Discontinuous MPS, with protection around the poles, have not been analyzed since they give very little reduction in risk of injury. The distance from the road is important for both avoidance of accidents and the risk of injuries. The most common injuries in guardrail accidents are legs, head, chest and pelvis. All studies show a very high risk of being killed or seriously injured when motorcyclists collide with guardrails. The technical specification TS 1317-8 specifies a test method in which a dummy slid with head first into a guardrail at an angle where few accidents happen. It is a method that could be simplified, without reducing the safety for motorcyclists. There is enough knowledge and experience to come to decisions that will reduce the risk of injury to motorcyclists in terms of design and installation of the guardrails. It is difficult to draw fair conclusions from international research. There are huge differences in the barriers used in different countries, the extent of barriers installed and how the barriers are installed. This makes a comparison more difficult since one type of barrier can be used very rarely or not at all. This is the case concerning concrete barriers in Sweden. (A)]]></description>
      <pubDate>Wed, 23 May 2018 11:35:53 GMT</pubDate>
      <guid>https://trid.trb.org/View/1511502</guid>
    </item>
    <item>
      <title>Trees in the Roadside as Factor in Road Safety in Poland</title>
      <link>https://trid.trb.org/View/1503526</link>
      <description><![CDATA[Roadside-related crashes occur when vehicles run off the road. The majority of the crashes have severe outcomes, especially when an object is hit (tree, pole, supports, culvert headwall, or safety barrier). Understanding how the different road and roadside elements affect safety must be based on in-depth studies. Data from sections of Polish national and regional roads were used to building crash predictive models quantifying effects of road design and traffic factors on and their effect on road safety measures.]]></description>
      <pubDate>Thu, 01 Mar 2018 10:07:52 GMT</pubDate>
      <guid>https://trid.trb.org/View/1503526</guid>
    </item>
    <item>
      <title>An Evaluation of the Effectiveness and Cost-Effectiveness of a Rural Run-Off-Road Crash Program in Western Australia</title>
      <link>https://trid.trb.org/View/1503461</link>
      <description><![CDATA[Single vehicle run-off-road crashes accounted for almost 60% of all road deaths and serious injuries in regional and remote Western Australia (WA) from 2008 to 2012. A total of 984 kilometres of rural WA roads received road treatments under the rural “Run-off-road Crash Program” from 2012 to 2015. This study aims to evaluate the effectiveness of the WA program in reducing the frequency and severity of run-off-road crashes, as well as the program’s cost-effectiveness in terms of savings to the community for each dollar invested.]]></description>
      <pubDate>Thu, 01 Mar 2018 10:00:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/1503461</guid>
    </item>
    <item>
      <title>Geometric Design Guide for Canadian Roads: Chapter 7 - Roadside Design</title>
      <link>https://trid.trb.org/View/1483920</link>
      <description><![CDATA[The Geometric Design Guide for Canadian Roads contains the current design and human factors research and practices for roadway geometric design. It replaces the 1999 edition of the Guide and subsequent revisions. The Guide provides guidance to planners and designers in developing design solutions that meet the needs of a range of users while addressing the context of local conditions and environments. Design guidelines for freeways, arterials, collectors, and local roads, in both urban and rural locations are included as well as guidance for integrated bicycle and pedestrian design.  The Guide is organized into ten chapters to cover the entire design process from design philosophy and roadway classification to design parameters and specific guidelines for the safe accommodation of vehicles, cyclists and pedestrians on linear road elements and at intersections. The chapters are: Design Philosophy; Design Controls, Classification and Consistency; Alignment and Lane Configuration; Cross Section Elements; Bicycle Integrated Design; Pedestrian Integrated Design; Roadside Design; Access; Intersections; and Interchanges.  Chapter 7 – Roadside Design introduces road safety concepts and the use of quantitative analysis to evaluate roadside safety design options. The fundamental concept of the clear zone is outlined and how the concept can be applied through provision of appropriate cross section and drainage elements to allow for driver recovery. Mitigation and protection techniques to reduce the severity of fixed-object collisions with roadside furniture including signs, luminaires and traffic barriers are outlined. A discussion of roadside design in urban environments and for low volume roads is also included.]]></description>
      <pubDate>Thu, 28 Sep 2017 12:27:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/1483920</guid>
    </item>
    <item>
      <title>In-depth crash investigation in South Australia and its use in roadside safety research</title>
      <link>https://trid.trb.org/View/1482045</link>
      <description><![CDATA[This paper gives an overview of the in-depth crash investigation activity conducted by the Centre for Automotive Safety Research (CASR) at the University of Adelaide, South Australia. The investigations aim to collect representative samples of metropolitan and rural crashes within 100 km of Adelaide. To focus on both areas within the same period adjustments to the method of crash investigations had to be made. Recent changes in method include: an expansion in on-call hours for the crash investigation team, providing the option of a phone interview for crash participants to discuss the crash, and downloading objective crash data from vehicle airbag control modules. These changes have resulted in: increased representativeness of crashes by hour of day; a decrease in the over-representation of fatal crashes in our sample; an increase in the proportion of crashes that involved a pedestrian, bicycle or scooter (moped); an increase in the proportion of crash participants consenting to an interview; and an increase in the objective data available, through airbag control module downloads. The data produced by in-depth crash investigations enabled research into road departures that found barriers were a more feasible solution than clear zones for eliminating serious and fatal injury resulting from run-off road crashes. This demonstrates how in-depth crash investigation at CASR enables research questions to be answered that cannot be answered with police report data alone.]]></description>
      <pubDate>Tue, 26 Sep 2017 10:43:48 GMT</pubDate>
      <guid>https://trid.trb.org/View/1482045</guid>
    </item>
    <item>
      <title>Ireland: implementing research outputs on safety management from CEDR (Conference of European Road Directors) research programme: paper 3</title>
      <link>https://trid.trb.org/View/1454099</link>
      <description><![CDATA[This paper focuses on how Ireland, through progressively sharing information and research with other road authorities in the international community, has developed and implemented innovative solutions in order to mitigate the impact of road deaths and serious injuries on its roads. Since 2006 Ireland, along with other European National Road Administrations (NRAs), has agreed to share its road research priorities and to open up research budgets via the CEDR group - Conference of European Road Directors - which facilitates information exchange and experiences of road-related issues at a European level. Among other achievements, this has enabled the organisation of successful transnational calls for research which, in turn, have delivered outstanding research projects which Transport Infrastructure Ireland (TII) has implemented to target its road safety needs. This paper demonstrates how Ireland, through implementing the safe system approach as detailed within these research projects, is seeking to actively reduce road deaths by aiming to minimise the effects of human error along with looking to: - minimise the risk of vehicles leaving the carriageway (e.g. via delineation) - provide adequate recovery space when vehicles do run off the road, and, - ensure that any collision that does occur in the roadside will be with objects that limit the impact forces on vehicle occupants to minor levels (no fatal or serious injury outcomes). This paper also covers how these research topics were developed and implemented so as to complement existing design standards and to influence how designers and motorway operators regard road safety and the whole life cost of collisions.]]></description>
      <pubDate>Thu, 09 Feb 2017 12:07:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/1454099</guid>
    </item>
    <item>
      <title>Using weigh-in-motion data to predict the likelihood of exceeding the capacity of a road safety barrier</title>
      <link>https://trid.trb.org/View/1454094</link>
      <description><![CDATA[Run-off road and head-on crashes together constitute around 38% of all casualty crashes and a higher proportion (closer to 50%) of all fatality crashes in Queensland, Australia. These statistics are a fair reflection of the national condition. Vehicles leaving the travelled way are a significant contributor to Australian road trauma. The Australian National Road Safety Strategy proposes a number of infrastructure treatments for tackling these two crash types, including the use of an appropriate road safety barrier. Road authorities deploy longitudinal road safety barriers primarily to prevent errant vehicles from impacting with hazardous roadside objects that could cause an adverse outcome for either the occupants of the errant vehicle or third parties. However, road safety barriers are not equal and are differentiated in the first instance by their capacity to contain impacts of different speed, mass and angle of incidence. While roadway departure speeds and departure angles are well-addressed in contemporary academic literature and methodologies for road safety barrier selection, the mass-distribution of the in-service vehicle fleet is less well represented. This study proposes the use of data obtained from weigh-in-motion technology to represent the mass-frequency distribution of the in-service vehicle fleet. Combined with roadway departures conditions reported by others, a methodology is presented for calculating the likelihood of vehicle-barrier impact exceeding the road safety barrier capacities prescribed by the predominant global test protocols for road safety barriers. The methodology is used to consider how different roadway configurations and traffic compositions might influence the likelihood of barrier capacity exceedance. The results from modelling of various scenarios are reported. The results suggest that the relative likelihood of barrier capacity exceedance varies as a function of cross-sectional geometry as well as traffic composition, so suggesting that a "one-size fits all" approach to road safety barrier selection is not appropriate.]]></description>
      <pubDate>Thu, 09 Feb 2017 12:07:09 GMT</pubDate>
      <guid>https://trid.trb.org/View/1454094</guid>
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