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Author: Nicholas J. Garber
Publisher:
ISBN:
Category : Roads
Languages : en
Pages : 68
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Book Description
In 2004, a total of 95,020 vehicle crashes occurred on highways under the jurisdiction of the Virginia Department of Transportation (VDOT). Of these, 39,847 crashes occurred on primary highways, and 345 of these were fatal crashes. VDOT's traffic engineers continue to place increasing emphasis on identifying causal factors for crashes to enhance the selection of appropriate and effective countermeasures. The purpose of this study was to identify causal factors and appropriate countermeasures for crashes occurring at high-risk locations on multilane primary highways from 2001 through 2006. These high-risk locations were identified by Fontaine and Reed (2006) in a VDOT safety corridor study. A total of 365 sites, 1 to 2 mi in length, were used in the study. The statewide sites were located on rural and urban highways with divided, undivided, and traversable medians, with about 40 sites per VDOT district. Crash data were extracted from police crash reports, and geometric data were collected through site visits. Operational data were collected using VDOT's resources. The analysis involved more than 34,000 crashes and was conducted using fault tree analysis and generalized linear modeling. The fault tree analysis was used to determine the critical fault path based on the probability of an event occurring. Individual fault trees were constructed for each collision type and for each highway classification. The generalized linear models were developed for different highway classifications: urban divided, urban undivided, urban traversable (central lanes that can be used for left turns in both directions), and rural divided highways. Models were developed for rear-end crashes and total crashes, and separate models were developed for injury crashes, property damage only (PDO) crashes, and injury + PDO crashes. Appropriate potential countermeasures were then identified based on the significant causal factors identified in the models. The results indicated that rear-end crashes were the predominant type of crash, representing 56% of all PDO crashes on urban divided highways and 37% of all PDO crashes on rural divided highways. Implementing the recommended countermeasures for total, rear-end, and angle crashes for different assumed levels of rehabilitation is expected to result in a crash reduction of up to about 40% depending on the site and level of rehabilitation undertaken. A benefit/cost analysis showed that the benefit/cost ratios were higher than 1 for all levels of countermeasure implementation.
Author: Nicholas J. Garber
Publisher:
ISBN:
Category : Roads
Languages : en
Pages : 68
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Book Description
In 2004, a total of 95,020 vehicle crashes occurred on highways under the jurisdiction of the Virginia Department of Transportation (VDOT). Of these, 39,847 crashes occurred on primary highways, and 345 of these were fatal crashes. VDOT's traffic engineers continue to place increasing emphasis on identifying causal factors for crashes to enhance the selection of appropriate and effective countermeasures. The purpose of this study was to identify causal factors and appropriate countermeasures for crashes occurring at high-risk locations on multilane primary highways from 2001 through 2006. These high-risk locations were identified by Fontaine and Reed (2006) in a VDOT safety corridor study. A total of 365 sites, 1 to 2 mi in length, were used in the study. The statewide sites were located on rural and urban highways with divided, undivided, and traversable medians, with about 40 sites per VDOT district. Crash data were extracted from police crash reports, and geometric data were collected through site visits. Operational data were collected using VDOT's resources. The analysis involved more than 34,000 crashes and was conducted using fault tree analysis and generalized linear modeling. The fault tree analysis was used to determine the critical fault path based on the probability of an event occurring. Individual fault trees were constructed for each collision type and for each highway classification. The generalized linear models were developed for different highway classifications: urban divided, urban undivided, urban traversable (central lanes that can be used for left turns in both directions), and rural divided highways. Models were developed for rear-end crashes and total crashes, and separate models were developed for injury crashes, property damage only (PDO) crashes, and injury + PDO crashes. Appropriate potential countermeasures were then identified based on the significant causal factors identified in the models. The results indicated that rear-end crashes were the predominant type of crash, representing 56% of all PDO crashes on urban divided highways and 37% of all PDO crashes on rural divided highways. Implementing the recommended countermeasures for total, rear-end, and angle crashes for different assumed levels of rehabilitation is expected to result in a crash reduction of up to about 40% depending on the site and level of rehabilitation undertaken. A benefit/cost analysis showed that the benefit/cost ratios were higher than 1 for all levels of countermeasure implementation.
Author: Nicholas J. Garber
Publisher:
ISBN:
Category : Low-volume roads
Languages : en
Pages : 60
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Book Description
Considerable efforts have been made in recent years to make highway travel safer. Traffic engineers continue to emphasize the identification of causal factors for crashes on individual sections and on different functional classes of highways as an area of emphasis. If precise causal factors and corresponding countermeasures can be identified, traffic engineers in the roadway design field would be able to use that information to make Virginia's highways safer. The purpose of this study was to identify causal factors of crashes on two-lane highways and corresponding effective countermeasures that should significantly reduce these crashes. The scope of the research was limited to two-lane highways in Virginia with data from 2001 through 2004. The researchers identified 143 five- to ten-mile stretches of two-lane highways in Virginia that proportionally represented each of the counties in Virginia. Relevant data elements that included time of crash, road and weather conditions, driver action, and type of collision were extracted from the relevant police reports. Traffic volumes and speed data were obtained from VDOT publications. Global positioning system data collected for each site provided information on grading and curvature of the sites. Signing and speed limit data were also collected for each site. The final dataset consisted of nearly 10,000 crashes and more than 30 variables, grouped under different highway classifications (urban primary, urban secondary, rural primary, rural secondary) and collision type (rear-end, angle, head-on, sideswipe, run-off-the-road [ROR], deer, and other). Fault tree analysis was used to identify the associated causal factors, and generalized linear models were developed from which the significant causal factors were identified. The results indicated that ROR crashes were the predominant type of crash, followed by rear-end, angle, and deer crashes. These crashes represented nearly 70% of all crashes. The significant causal factors for ROR crashes were found to be curvature and annual average daily traffic. One of the four recommendations is that a plan for correcting the geometric deficiencies of the significant causal factors at sites with high ROR crashes be developed and implemented. The economic benefits of improving the radii at locations with predominantly ROR crashes were investigated using a sensitivity analysis on the benefit/cost ratios for different levels of improvements and expected crash reductions. In all cases, the ratio was higher than 1, with a range of 1.16 to 9.60.
Author: Rachael Elizabeth Abel
Publisher:
ISBN:
Category :
Languages : en
Pages : 168
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Book Description
Author: Nicholas J. Garber
Publisher:
ISBN:
Category : Intelligent transportation systems
Languages : en
Pages : 72
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Book Description
The use of large trucks has steadily increased since the passage of the Surface Transportation Assistance Act to the point where they now account for over 50% of vehicle traffic on some highways in Virginia. Projections now forecast that large-truck travel will grow at twice the rate of personal vehicle travel in the near future. Although several studies have been conducted to determine the effects of large trucks on safety on multilane primary and interstate highway systems, the effects on two-lane secondary roads have been largely ignored. This study identified the causal factors and predominant types of large-truck crashes on two-lane secondary roads in Virginia and compared the large-truck crash rates for two-lane secondary roads and two-lane primary roads. The study also identified advanced technologies associated with intelligent transportation systems (ITS) that can be used to minimize the causal factors of large-truck crashes on these roads. The results showed that large-truck crash rates are significantly higher on two-lane secondary roads than on two-lane primary roads, with the predominant types of crashes being angle, rear end, sideswipe same direction, and sideswipe opposite direction. The study identified several ITS technologies that can be used to mitigate the predominant causal factors and recommends a pilot study to test the effectiveness of one such system.
Author: Ajmal Hamidi
Publisher:
ISBN:
Category : Roads
Languages : en
Pages : 58
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Book Description
The Virginia Department of Transportation (VDOT) has been developing safety performance functions (SPFs) as a way to identify sites with a potential for safety improvement more effectively. An SPF estimates the expected safety performance of a roadway as a function of its characteristics. Using SPFs, VDOT can identify which roads have a significantly higher number of crashes than would be expected based on site conditions. Other VDOT studies have developed SPFs with a microscopic perspective that separately examine individual intersections or discrete roadway segments. The purpose of this study was to develop an SPF-based methodology to conduct more intermediate-scale safety analyses. VDOT's Traffic Engineering Division indicated that such a methodology would be useful for corridor screening and planning-level applications. The scope of the study was limited to the following roadway types in Virginia's primary system: rural two-lane, rural multilane divided, rural multilane undivided, urban two-lane, urban multilane divided, and urban multilane undivided. For each type, roadway inventory data, traffic volume data, and crash data from 2003 through 2007 were compiled and integrated into a database. This study then took an approach that diverged from that of other SPF research to develop intermediate-scale SPFs. Instead of crashes at intersections and on roadway segments being separated, intersection and segment crashes were combined and mapped onto the appropriate roadway inventory links. In addition, site aggregation was performed to combine similar, adjacent roadway links into longer aggregated sites. SPFs were then generated from these aggregated sites through regression analysis. A site prioritization demonstration was then performed using the aggregate SPFs and aggregate sites to create lists of sites with the highest potential for safety improvement. Finally, a comparison of these lists and those generated by the critical rate method produced quantitative evidence of the advantage of the developed SPF-based methodology over the traditionally used critical rate method. Once implemented, the methodology developed in this study should enable VDOT to conduct corridor screening and planning-level analyses in a more effective and cost-efficient manner.
Author: John Sanders Miller
Publisher:
ISBN:
Category : Roads
Languages : en
Pages : 68
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Book Description
Intersection crashes cost the nation more than $40 billion annually, account for more than one-fifth of all highway crash fatalities nationally, and totaled almost 75,000 in the Virginia Department of Transportation's (VDOT) Northern Virginia District for the period 2001 through 2006. Although VDOT maintains several databases containing more than 170 data elements with detailed crash, driver, and roadway attributes, it was not clear to users of these databases how these data elements could be used to identify causal factors for these intersection crashes for two reasons: (1) the quality of some of the data elements was imperfect, and (2) and random variation is inherent in crashes. This study developed an approach to address these two issues. To address the first issue, the completeness and accuracy of the 179 data elements that comprise the VDOT CRASHDATA database were assessed. For the 76 data elements for which the quality of the data was imperfect, eight rules for using these elements were developed. The rules indicate which data elements should be used in certain circumstances; which data elements are incomplete; and how to manipulate the data for certain applications. To address the second issue, classification trees and crash estimation models (CEMs) were developed. The trees showed that specific causal factors, such as the approach alignment or surface condition, successfully indicate whether a given crash was a rear-end or angle crash. By extension, the trees suggested that intersection crashes were not purely random. Accordingly, it was feasible to develop CEMs that for 17 intersection classes predicted the number of crashes for a 1-year period for four crash types: rear-end, angle, injury, and total. The 68 CEMs showed deviance-based pseudo R-square values between 0.07 and 0.74, suggesting that the causal factors explained some, but not all, of the variation in intersection crashes. The CEMs varied by intersection class. Two actions with regard to crash data analysis may be taken as detailed in this report. First, the eight crash data quality rules developed in this study should be considered for use on a case-by-case basis for studies requiring intersection crash data. Second, when they are collected at the crash scene, the variables that successfully classified rear-end and angle crashes may be given increased attention such that every effort is made to ensure these data elements are accurately recorded.
Author: European Conference of Ministers of Transport
Publisher: OECD Publishing
ISBN: 9282103781
Category :
Languages : en
Pages : 286
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Book Description
Speeding is the number one road safety problem in a large number of OECD/ECMT countries. It is responsible for around one third of the current, unacceptably high levels of road fatalities. Speeding has an impact not only on accidents but also on the ...
Author: Charles V. Zegeer
Publisher: DIANE Publishing
ISBN: 1428995501
Category : Pedestrian accidents
Languages : en
Pages : 164
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Book Description
This guide is intended to provide information on how to identify safety and mobility needs for pedestrians with the roadway right-of-way. Useful for engineers, planners, safety professionals and decision-makers, the guide covers such topics as: the Walking Environment including sidewalks, curb ramps, crosswalks, roadway lighting and pedestrian over and under passes; Roadway Design including bicycle lanes, roadway narrowing, reducing the number of lanes, one-way/two-way streets, right-turn slip lanes and raised medians; Intersections with roundabouts, T-intersections and median barriers; and Traffic calming designs.
Author: ITE (Institute of Transportation Engineers)
Publisher: John Wiley & Sons
ISBN: 1118762304
Category : Technology & Engineering
Languages : en
Pages : 688
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Book Description
Get a complete look into modern traffic engineering solutions Traffic Engineering Handbook, Seventh Edition is a newly revised text that builds upon the reputation as the go-to source of essential traffic engineering solutions that this book has maintained for the past 70 years. The updated content reflects changes in key industry standards, and shines a spotlight on the needs of all users, the design of context-sensitive roadways, and the development of more sustainable transportation solutions. Additionally, this resource features a new organizational structure that promotes a more functionally-driven, multimodal approach to planning, designing, and implementing transportation solutions. A branch of civil engineering, traffic engineering concerns the safe and efficient movement of people and goods along roadways. Traffic flow, road geometry, sidewalks, crosswalks, cycle facilities, shared lane markings, traffic signs, traffic lights, and more—all of these elements must be considered when designing public and private sector transportation solutions. Explore the fundamental concepts of traffic engineering as they relate to operation, design, and management Access updated content that reflects changes in key industry-leading resources, such as the Highway Capacity Manual (HCM), Manual on Uniform Traffic Control Devices (MUTCD), AASSHTO Policy on Geometric Design, Highway Safety Manual (HSM), and Americans with Disabilities Act Understand the current state of the traffic engineering field Leverage revised information that homes in on the key topics most relevant to traffic engineering in today's world, such as context-sensitive roadways and sustainable transportation solutions Traffic Engineering Handbook, Seventh Edition is an essential text for public and private sector transportation practitioners, transportation decision makers, public officials, and even upper-level undergraduate and graduate students who are studying transportation engineering.
Author: Bhagwant Naraine Persaud
Publisher:
ISBN:
Category : Transportation
Languages : en
Pages : 88
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Book Description
TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 295: Statistical Methods in Highway Safety Analysis focus on the type of safety analysis required to support traditional engineering functions, such as the identification of hazardous locations and the development and evaluation of countermeasures. Analyses related specifically to driver and vehicle safety are not covered, but some statistical methods used in these areas are of relevance and are summarized where appropriate.
