The purpose of this study was to review road geometric standards (which are currently based on passenger car characteristics) taking into account truck driver eye-height and braking distance. A survey of truck driver eye-height gave a 5th... more
The purpose of this study was to review road geometric standards (which are currently based on passenger car characteristics) taking into account truck driver eye-height and braking distance. A survey of truck driver eye-height gave a 5th percentile height of 1.87 m. Owing to the lack of empirical data on the braking performance of trucks, a theoretical approach was used to estimate design braking distances on the basis of the maximum legal braking distances of South African trucks. In addition, two American surveys provided further data on truck braking distances. A comparison between the speeds of cars and trucks in 1981 and 1982 on Transvaal freeways gave a consistent 17 km/h difference between similar percentiles. It was thus possible to compare the elements of road geometric design based on stopping sight distance for passenger cars travelling at a given speed and trucks travelling at a 17 km/h lower speed. It was found that, at design speeds above 100 km/h, the current standards for stopping sight distance, k-values for sag vertical curves and lateral clearance on horizontal curves were insufficient for trucks. Revised values for design speeds above 100 km/h, termed recommended values, are proposed for use until South African truck braking distances are known. (Author/TRRL)
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This paper describes the key fundamentals of road safety. These fundamentals shape the Highway Safety Manual (HSM), First Edition, expected to be published in 2009. This paper is divided into four main sections: accidents as the basis for... more
This paper describes the key fundamentals of road safety. These fundamentals shape the Highway Safety Manual (HSM), First Edition, expected to be published in 2009. This paper is divided into four main sections: accidents as the basis for estimating safety (Section 1), defining safety (Section 2), fundamentals of safety estimation (Section 3), and safety evaluation, crash causation, and Accident Modification Factors (Section 4). It is noted that the use of the word “accident” does not imply that such an event is unavoidable; it indicates the need to study the randomness that is inherent in accident counts.
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The questions of an appropriate speed limit and a design speed for rural freeways are discussed. Sections of five freeway schemes, which between them are located in a variety of topographies, were selected for investigation. These... more
The questions of an appropriate speed limit and a design speed for rural freeways are discussed. Sections of five freeway schemes, which between them are located in a variety of topographies, were selected for investigation. These sections were redesigned to different design speeds and the construction costs of each alternative estimated. The total operating costs for each alternative design were computed at different speed limits. It is recommended that: the maximum rural speed limit should be reduced to 90 km/h; traffic authorities should raise the level of enforcement; the National Road Safety Council should conduct a campaign supporting lower speed limits; and road authorities should not use a rural freeway design speed of less that 120 km/h. For the covering abstract of the conference see IRRD 288720. (TRRL)
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The Federal Highway Administration (FHWA) conducted a capabilities assessment for each State in terms of the collection, management, and use of roadway safety data. This project is part of the Roadway Safety Data Partnership (RSDP), a... more
The Federal Highway Administration (FHWA) conducted a capabilities assessment for each State in terms of the collection, management, and use of roadway safety data. This project is part of the Roadway Safety Data Partnership (RSDP), a collaborative effort between the FHWA and States to ensure that they are best able to develop robust data-driven safety capabilities. This final report provides an overview of findings based upon the assessment of fifty States plus the District of Columbia and Puerto Rico.
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Drivers are informed of changes in their driving environment through numerous visual warnings by way of traffic signs, signals, and vehicles ahead of them. Transverse Rumble Strips (TRS) are unique as they communicate to drivers'... more
Drivers are informed of changes in their driving environment through numerous visual warnings by way of traffic signs, signals, and vehicles ahead of them. Transverse Rumble Strips (TRS) are unique as they communicate to drivers' kinesthetic (movement) and auditory senses. The TRS design parameters and elements described in this guide incorporate the findings of extensive reviews of research and practices and are based on the operating speed of the roadway and decision sight distances as interpreted from the Transportation Association of Canada (TAC) Geometric Design Guide for Canadian Roads. (A)
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In Canada, a number of provinces have developed guidelines and policies for the implementation of shoulder rumble strips. As well, as of 2000, Alberta is the only province that has implemented centreline rumble strips. Other provinces... more
In Canada, a number of provinces have developed guidelines and policies for the implementation of shoulder rumble strips. As well, as of 2000, Alberta is the only province that has implemented centreline rumble strips. Other provinces wanting to apply shoulder and centreline rumble strips lack experience and require guidance based on other jurisdictions' results of such applications. The purpose of this document is to provide highway agencies with a summary of current practices to assist these agencies in the development of local guidelines and policies. The Executive summary provides an overview of the best practices and can be used as a quick reference to the key recommendations that are provided throughout the body of this document. (A)
Research Interests: Engineering and Strips
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A true assessment of the HOV lanes performance rests with how well their efficiency measures compare to the goals of the system. It can be concluded that the Metropolitan Toronto HOV lanes are effective based on the following observations... more
A true assessment of the HOV lanes performance rests with how well their efficiency measures compare to the goals of the system. It can be concluded that the Metropolitan Toronto HOV lanes are effective based on the following observations relating to 3 of the 5 objectives: (1) Move more people in a lane at a faster pace; (2) Improve transit operation and motivate increased ridership; (3) Increase vehicle occupancy by promoting carpooling; (4) and (5) Reduction of fuel consumption and vehicular emissions resulting from HOV implementation. Monitoring measures were inconclusive, however, modelling results suggest that it is unlikely that these objectives have been met through HOV implementation.
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The purpose of the investigation was to expand upon the information obtainable from the South African Police accident records regarding single-vehicle accidents. The in-depth studies included visits to accident sites, questioning the... more
The purpose of the investigation was to expand upon the information obtainable from the South African Police accident records regarding single-vehicle accidents. The in-depth studies included visits to accident sites, questioning the various persons involved in the accidents and filling in a questionnaire for each accident. In all, 75 rural and 10 urban accidents were investigated. The information obtained from the accidents is presented in the form of tree diagrams. It is concluded that overturning accidents are mainly caused by lack of driving experience (inappropriate reactions such as oversteering, etc.) or lack of concentration or both, usually accompanied by high speed. The roadside and median surfaces were not always safely traversable by vehicles and objects were situated too close to the roadway providing drivers with less chance of controlling or stopping their vehicles. These findings will be used as guidelines for further studies on single-vehicle accidents.
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During the last 15 years, legislation has moved purposefully towards making safety a central, explicit, comprehensive, and integrated part of transportation planning. Safety management systems have advanced. Data and analytical tools have... more
During the last 15 years, legislation has moved purposefully towards making safety a central, explicit, comprehensive, and integrated part of transportation planning. Safety management systems have advanced. Data and analytical tools have been improved and refined, and the effects of countermeasures have become better understood. The recently enacted Safe, Accountable, Flexible, Efficient Transportation Equity Act (SAFETEA-LU) builds on previous legislation in giving specific and increasing recognition to safety issues. Major highway agencies such as DOTs, metropolitan planning organizations (MPOs), transit agencies, and local governments are usually large, well-established organizations where change may not come naturally. How do agencies vary in their commitment to safety? Has safety become a more explicit and fully integrated part of all aspects of transportation planning? Safety legislation can lay out requirements for highway agencies to bring about the implementation of the legislation and can support those requirements with the carrot of project funding and the stick of penalties, but the legislation’s ultimate success or failure in reducing fatalities and injuries is likely to be affected by the ability of individual agencies to implement the legislation effectively and to sustain it by means of a strong safety culture. Such a culture would accept and adopt the legislation in the full spirit intended and would succeed in entrenching safety as its central and permanent focus for decision making.
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This report looks at three aspects of the effect of speed limits on rural freeways. It first examines the interrelationship of speed limits and minimum design speed with total operating costs, total community costs, fuel consumption and... more
This report looks at three aspects of the effect of speed limits on rural freeways. It first examines the interrelationship of speed limits and minimum design speed with total operating costs, total community costs, fuel consumption and accidents, on rural freeways designed to different minimum design speeds. Secondly, it investigates the consequences of increasing the maximum speed limit from the existing 100km/h to 120km/h. Thirdly, a brief report is presented of the behaviour of car drivers on Traansvaal freeways over an 80-week period during which the speed limit was 100km/h. (TRRL)
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Warrants for the provision of uncontrolled and signal controlled midblock pedestrian crossings are proposed in this report. Based on empirical data, pedestrian walking speed is separately established for typical and elderly pedestrians.... more
Warrants for the provision of uncontrolled and signal controlled midblock pedestrian crossings are proposed in this report. Based on empirical data, pedestrian walking speed is separately established for typical and elderly pedestrians. Speed limit, different effective widths of roads and direction of flow are considered in the determination of the proposed warrants. It is concluded that the adoption of the warrants will lead to a reduction in the number of inappropriate installations to be seen in our cities and towns. In addition, publicity, education and, most of all, effective law enforcement are needed to improve the safety of pedestrian crossing facilities in South Africa. (Author)
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This paper addresses the relationship between traffic safety and various landscape treatments on five arterial roads. Each road is different in various aspects but was consistently enhanced using landscape architectural materials and road... more
This paper addresses the relationship between traffic safety and various landscape treatments on five arterial roads. Each road is different in various aspects but was consistently enhanced using landscape architectural materials and road design. An examination of typical environmental mitigation scenarios in terms of cost and type of improvement is presented in relationship to the cost of accidents before and after the installation. Safety management is examined through an analysis of traffic accidents before and after the installation of the landscape improvements. Highway landscaping and visual design have been used as a cost-effective method to achieve purposes of environmental enhancement and community impact mitigation and appear to have an impact on traffic safety. The trend that is perceived is a decrease in mid-block accident frequency and severity following landscape enhancements. The findings here give a direction for future research efforts in understanding application o...
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Safety engineering research by the South African National Institute for Transport and Road Research on the location, layout and provision of mid-block pedestrian crossing facilities is discussed. Studies done revealed that the status of... more
Safety engineering research by the South African National Institute for Transport and Road Research on the location, layout and provision of mid-block pedestrian crossing facilities is discussed. Studies done revealed that the status of these crossing facilities is unsatisfactory and that the existing recommendations and warrants for the provision of facilities are either subjective or inflexible. It is suggested that they should be revised. For uncontrolled mid-block crossings no vehicular or pedestrian volumes are specified in the warrants, and for signal- controlled mid-block crossings the fixed vehicular and pedestrian volume warrant ignores criteria such as road width, directional flow of traffic, vehicle speed, safe gap distribution, pedestrian walking speed, elderly pedestrians, etc. New warrants are proposed for the provision of both uncontrolled and signal-controlled mid-block pedestrian crossings based on the above criteria. The proposed South African warrants are compared...
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The purpose of this paper is to describe an incremental analysis methodology which may be used to manage road safety using only historical collision data and tools no more advanced than a spreadsheet for those road agencies which lack the... more
The purpose of this paper is to describe an incremental analysis methodology which may be used to manage road safety using only historical collision data and tools no more advanced than a spreadsheet for those road agencies which lack the resources to apply more advance techniques. Although the methodologies of this paper are not new, it is the first to describe the analysis within a multi-disciplinary framework. A further breakdown of collisions by emphasis area is used to identify the top areas of safety concern that require the involvement of engineering, enforcement, health, and education combined. In addition, a more detailed analysis looks for the over-representation of different collision types by emphasis area allowing agencies to identify locations where specific collisions are occurring at higher proportions than would statistically be expected. The paper provides example calculations to illustrate over-representation, which can then be applied to emphasis area collisions.
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ABSTRACT
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Permanent raised pavement markers (PRPMs) often are used to improve preview distances and guidance for drivers in inclement weather and low light conditions. However, studies in three states in the United States have raised concerns about... more
Permanent raised pavement markers (PRPMs) often are used to improve preview distances and guidance for drivers in inclement weather and low light conditions. However, studies in three states in the United States have raised concerns about these devices after negative safety effects were found. To address these concerns, an NCHRP project was initiated to assess definitively the safety effects of PRPMs and to develop guidelines for their implementation, by using state-of-the-art methodology and a database from across the United States. This project evaluated the safety performance of snow-plowable PRPMs on two-lane roadways and four-lane freeways by using data collected from five states. The results show that on two-lane roadways selective installations in one state were accompanied by highly significant decreases in total, nighttime, and wet-weather crashes, whereas there was no apparent overall safety benefit for the nonselective installations in two states. A disaggregate analysis ...
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Introduced are the ideas found in the integrated safety management system (ISMSystem), published as National Cooperative Highway Research Program Report 501. The ISMSystem is founded upon the principle that aligning the activities of... more
Introduced are the ideas found in the integrated safety management system (ISMSystem), published as National Cooperative Highway Research Program Report 501. The ISMSystem is founded upon the principle that aligning the activities of different agencies within a jurisdiction can result in a level of safety unobtainable by those agencies working independently and in decision-making isolation. In addition to providing highway safety benefits, implementing the ISMSystem should result in cost savings when the resources of different agencies are pooled and shared. The ISMSystem describes an organizational structure that includes a coalition of highway safety agencies that develops a common mission and vision at the highest level of management. Safety professionals with expertise in relevant emphasis areas are recruited into teams to address the specific goals set out by the coalition and in doing so produce action plans that integrate the activities of the implementing agencies. The integ...
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Federal Highway Administration2019PDFTech ReportScopatz, Robert A.Albee, MattBahar, Geni BrafmanBrown, RichardCarter, DanielDeFisher, JoshuaBueno, Claudio F.Gooch, JeffGoughnour, ElissaGross, FrankHamilton, IanHarmon, TimHarrison, Frances... more
Federal Highway Administration2019PDFTech ReportScopatz, Robert A.Albee, MattBahar, Geni BrafmanBrown, RichardCarter, DanielDeFisher, JoshuaBueno, Claudio F.Gooch, JeffGoughnour, ElissaGross, FrankHamilton, IanHarmon, TimHarrison, Frances D.Signor, KariSmith, Sarah M.Stickel, JackTaha, SaleemTang, EricTurner, BethanyWyatt, TonyZhou, YuyingStrawder, EstherGigliotti, DanaUnited States. Federal Highway Administration. Office of SafetyVHB/Vanasse Hangen Brustlin, Inc.United States. Federal Highway Administration. Office of SafetyUnited StatesTraffic dataData analysisData collectionData managementHighway safetyPavement performanceRoadway safety dataData collectionData managementData governanceData analysisData integrationSafety performance measurementCapability assessmentCapability maturity modelFHWA-SA-19-018DTFH61-16-D-00005Strawder, EstherThe Federal Highway Administration (FHWA) conducted a second roadway data capabilities assessment of each State\u2019s collection, analysis, management, and use of roadway safety data. This final report provides an overview of findings based upon the assessment of fifty States plus the District of Columbia and Puerto Rico.109
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This paper outlines key points of the extensive literature review and state of the practice by iTRANS Consulting Inc., which was conducted for the Transportation Research Board under the National Cooperative Highway Research Program... more
This paper outlines key points of the extensive literature review and state of the practice by iTRANS Consulting Inc., which was conducted for the Transportation Research Board under the National Cooperative Highway Research Program 17-28, with the objective of developing guidelines for use of pavement marking materials and markers based on their safety impact and cost-effectiveness. The Federal Highway Administration is actively pursuing research to determine the minimum retroreflectivity requirements for pavement markings. In all cases, the research to determine minimum retroreflectivity requirements is based on drivers? minimum detection distances. As is no surprise, research to determine minimum detection distances has determined that brighter markings can be seen further away; there is an unwritten assumption is that increasing minimum detection distances increases safety. Unfortunately, there are situations, such as sharp curves with low design standards, where in fact increas...
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Drivers are informed of changes in their driving environment through numerous visual warnings by way of traffic signs, signals, and vehicles ahead of them. Transverse Rumble Strips (TRS) are unique as they communicate to drivers'... more
Drivers are informed of changes in their driving environment through numerous visual warnings by way of traffic signs, signals, and vehicles ahead of them. Transverse Rumble Strips (TRS) are unique as they communicate to drivers' kinesthetic (movement) and auditory senses. The TRS design parameters and elements described in this guide incorporate the findings of extensive reviews of research and practices and are based on the operating speed of the roadway and decision sight distances as interpreted from the Transportation Association of Canada (TAC) Geometric Design Guide for Canadian Roads. (A)
Research Interests: Engineering and Strips
A conventional approach to reducing lane departure crashes is to improve path delineation, in particular on curves. Current treatments on two-lane rural highways include permanent raised pavement markers (PRPMs) and rumble strips. This... more
A conventional approach to reducing lane departure crashes is to improve path delineation, in particular on curves. Current treatments on two-lane rural highways include permanent raised pavement markers (PRPMs) and rumble strips. This paper considers the effect of these treatments on driver behaviour and on safety. For the covering abstract of this conference see ITRD number E211395.
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Better quantitative methods and a single authoritative document for estimating safety impacts are needed to facilitate the incorporation of transportation safety of all road users into the decision-making process. The need for a highway... more
Better quantitative methods and a single authoritative document for estimating safety impacts are needed to facilitate the incorporation of transportation safety of all road users into the decision-making process. The need for a highway safety manual has been identified, and content development is underway through several NCHRP projects. Language: en
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The Federal Highway Administration (FHWA) conducted a capabilities assessment for each State in terms of the collection, management, and use of roadway safety data. This project is part of the Roadway Safety Data Partnership (RSDP), a... more
The Federal Highway Administration (FHWA) conducted a capabilities assessment for each State in terms of the collection, management, and use of roadway safety data. This project is part of the Roadway Safety Data Partnership (RSDP), a collaborative effort between the FHWA and States to ensure that they are best able to develop robust data-driven safety capabilities. This final report provides an overview of findings based upon the assessment of fifty States plus the District of Columbia and Puerto Rico.
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This paper lists and describes the different avenues presented to manage run-off-road collisions, and focuses on six engineering treatments that can reduce the frequency and severity of run-off-road collisions. There are three key... more
This paper lists and describes the different avenues presented to manage run-off-road collisions, and focuses on six engineering treatments that can reduce the frequency and severity of run-off-road collisions. There are three key objectives for roadway and roadside design that can be addressed to reduce the number of run-off-road collisions: keep the vehicle in the travel lane, assist drivers that encroach onto the roadside to regain control of the vehicle, and reduce the severity of run-off-road collisions if the first two objectives were not met. These three objectives can be obtained through many different avenues of roadside design. The decision of which treatment to use can be facilitated through the use of the Accident Modification Factors. Each of these treatments is accompanied by the best estimate of Accident Modification Factor(s) available to date based on work currently underway to develop a Highway Safety Manual for the Transportation Research Board.
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Roadway departure crashes, which result from a vehicle crossing an edge line or center line or leaving the roadway, were responsible for 58% of accident fatalities in 2006. This article provides a comprehensive overview of the problem of... more
Roadway departure crashes, which result from a vehicle crossing an edge line or center line or leaving the roadway, were responsible for 58% of accident fatalities in 2006. This article provides a comprehensive overview of the problem of roadway departure crashes. Research has shown that roadway departure crashes mostly occur on two-lane local highways and are overrepresented on horizontal curves. Alcohol, fatigue, distraction and speed are contributing factors. Decreasing these crashes will require a comprehensive plan with integrated safety activities developed through participation at all levels of highway agencies. The actions required to ensure data-driven decisions and cost-effective implementation currently are taking place. Research is being funded to investigate the relationship among safety and operational and design elements. Practitioners are receiving training and political guidance to assist in their effort to increase highway safety. These steps should help to reduce ...
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... National Cooperative Highway Research Program Geni Bahar Maurice Masliah Tara Erwin Errol Tan iTRANS Consulting Richmond Hill, Ontario, Canada ... The research team recognizes the participation of the following iTRANS staff members:... more
... National Cooperative Highway Research Program Geni Bahar Maurice Masliah Tara Erwin Errol Tan iTRANS Consulting Richmond Hill, Ontario, Canada ... The research team recognizes the participation of the following iTRANS staff members: Phoebe Fu, ...
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This report develops a proposed agenda of prioritized safety research needs in the area of highway infrastructure and operations. It was developed to provide options to the U.S. transportation community on how to direct research to the... more
This report develops a proposed agenda of prioritized safety research needs in the area of highway infrastructure and operations. It was developed to provide options to the U.S. transportation community on how to direct research to the areas where it can provide the most benefit. The agenda is based on a prioritization methodology developed by the research team, which can be applied on a recurring basis to update the agenda over time. The methodology is included as a spreadsheet tool on the CD-ROM, CRP-CD-127, accompanying this report. A wide range of background and supporting materials are also provided on the CD-ROM, including a user guide for the prioritization tool. The report itself includes a list of specific prioritized research topics divided into two categories: (1) applied research that lends itself to the development of new Crash Modification Factors (CMFs) and (2) fundamental and applied research for which CMFs are not appropriate. Appendices A-O and R, which contain additional documentation from the research effort, are not printed in the published document. These materials are available for download from the TRB website. Both the agenda and the methodology documented in this report will provide valuable input to those involved in the conduct and management of highway safety research at all levels of government, the private sector, and academia.
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During the last 15 years, legislation has moved purposefully towards making safety a central, explicit, comprehensive, and integrated part of transportation planning. Safety management systems have advanced. Data and analytical tools have... more
During the last 15 years, legislation has moved purposefully towards making safety a central, explicit, comprehensive, and integrated part of transportation planning. Safety management systems have advanced. Data and analytical tools have been improved and refined, and the effects of countermeasures have become better understood. The recently enacted Safe, Accountable, Flexible, Efficient Transportation Equity Act (SAFETEA-LU) builds on previous legislation in giving specific and increasing recognition to safety issues. Major highway agencies such as DOTs, metropolitan planning organizations (MPOs), transit agencies, and local governments are usually large, well-established organizations where change may not come naturally. How do agencies vary in their commitment to safety? Has safety become a more explicit and fully integrated part of all aspects of transportation planning? Safety legislation can lay out requirements for highway agencies to bring about the implementation of the legislation and can support those requirements with the carrot of project funding and the stick of penalties, but the legislation’s ultimate success or failure in reducing fatalities and injuries is likely to be affected by the ability of individual agencies to implement the legislation effectively and to sustain it by means of a strong safety culture. Such a culture would accept and adopt the legislation in the full spirit intended and would succeed in entrenching safety as its central and permanent focus for decision making.
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This paper describes a study that used data from rural two-lane roads in Arizona to illustrate two issues. One issue is the importance of selecting an appropriate sample size for calibrating the Highway Safety Manual (HSM) predictive... more
This paper describes a study that used data from rural two-lane roads in Arizona to illustrate two issues. One issue is the importance of selecting an appropriate sample size for calibrating the Highway Safety Manual (HSM) predictive models based on the desired accuracy of the calibration factor, instead of relying on the guidance from the HSM (the HSM recommends 30 to 50 sites with at least 100 crashes per year but provides no statistical basis for this guidance). The second issue is the usefulness of estimating calibration functions when individual calibration factors do not provide a proper fit of the local data. On the basis of the outcome of the exploration of these two issues, this study recommends a simple calibration function for predicting total crashes on rural two-lane roads in Arizona. This paper also provides a brief overview of a procedure in Microsoft Excel that can be used by practitioners (after appropriate training) to estimate simple calibration functions.
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... Toronto, Ontario, Canada HUGH MCGEE Bellomo-McGee, Inc. ... team recognizes the participation of the following iTRANS staff members: Phoebe Fu, Kevin Shen, Joseph Palmisano, Maurice Masliah, Tara Erwin, Megan Johnson, Margaret... more
... Toronto, Ontario, Canada HUGH MCGEE Bellomo-McGee, Inc. ... team recognizes the participation of the following iTRANS staff members: Phoebe Fu, Kevin Shen, Joseph Palmisano, Maurice Masliah, Tara Erwin, Megan Johnson, Margaret Parkhill, Michael Sone, Errol Tan, and ...