Author:
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ISBN:
Category :
Languages : en
Pages : 74

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Book Description

Author: Virginia. Traffic and Safety Division
Publisher:
ISBN:
Category : Roads
Languages : en
Pages : 88

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Book Description

Author: Virginia. Department of Highways
Publisher:
ISBN:
Category : Automobiles
Languages : en
Pages : 215

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Book Description

Author: Virginia. Department of Highways
Publisher:
ISBN:
Category : Automobiles
Languages : en
Pages : 88

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Book Description

Author: Michael D. Fontaine
Publisher:
ISBN:
Category : Automobile drivers
Languages : en
Pages : 87

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Book Description
This report presents the results of a field implementation of credible, well-enforced, and highly publicized speed limits on two limited access highways in Virginia. The two locations studied were the US 29 bypass around Altavista, VA and the US 58/US 220 bypass around Martinsville, VA. At both of these locations, an engineering study recommended that the posted speed limit be increased from 55 mph to 65 mph. Virginia State Police provided an additional 40 hours per month of overtime enforcement on the study sections for 1 year at the Martinsville site and 15 months at the Altavista site. A public information and education (PI & E) campaign that consisted of media reports, informational handouts, and educational roadside signs was also implemented to try to increase compliance with the new posted speed limits. Before and after data on public perception, crash experience, and speed were analyzed to assess the impact of the program. The public perception survey results showed that the new 65 mph speed limits were well supported by the public, with over 80 percent agreeing with the new speed limits. The speed data analysis showed that the average speed increased by a statistically significant margin of 3 to 4 mph immediately after the new speed limit was implemented. Speeds remained constant following the implementation of the new speed limit, even after the increased enforcement and the education campaign ended. A speed analysis by vehicle type showed some minor variations in how vehicles responded to the changes in speed limit, enforcement, and PI & E. These differences were usually not very large, however. No negative safety impacts were observed during the evaluation. The overall number of crashes did not change by a statistically significant margin relative to historic trends, although the number of severe crashes at the Martinsville site did decline by a statistically significant amount and the crash rate at Altavista showed more than a 20 percent decline. Speed variance did not significantly change between the period with the 55 mph limit and the period with the 65 mph limit. This suggests that crash likelihood was not increased due to the increased posted speed limit. The coefficient of variation of the speeds decreased slightly following the increase in speed limit, potentially indicating that interactions between vehicles may have declined slightly. The demonstration proved to be a success, with the change in speed limit being well supported by the public. Strict compliance with the posted speed limits improved from 5 to 10 percent before the project began to between 45 and 50 percent. The percentage of drivers traveling 10 mph or more over the limit declined from over 20 percent to only 2 to 3 percent. Survey respondents reported that the roadside signs were noticed the most often of any PI & E effort used, likely due to the fact that both sites were located on through routes in rural areas.

Author:
Publisher:
ISBN:
Category : Automobiles
Languages : en
Pages : 6

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Book Description
Average speeds for automobiles, trucks, and buses in the United States.

Author:
Publisher:
ISBN:
Category : Automobiles
Languages : en
Pages : 18

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Book Description
Average speeds for automobiles, trucks, and buses in the United States.

Author: Virginia. Traffic and Safety Division
Publisher:
ISBN:
Category : Speed limits
Languages : en
Pages : 45

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Book Description

Author: Jack D. Jernigan
Publisher:
ISBN:
Category : Interstate Highway System
Languages : en
Pages : 158

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Book Description
In April of 1987, Congress passed the Surface Transportation and Uniform Relocation Assistance Act of 1987, which allows the states to raise, without penalty, the speed limit on interstate highways outside of urbanized areas with a population of 50,000 or more. This study estimated that an increase in the rural interstate speed limit in Virginia would have both positive and negative outcomes.-The average speed traveled on the rural interstate highway system has already increased by 3.6 mph in Virginia; this is comparable to that experienced in states that have raised the speed limit. However, if the speed limit on the rural interstate highway system is raised from 55 mph to 65 mph, it is estimated that in the short run the average speed traveled on the rural interstate will increase by an additional 3 mph, from 60 mph to 63 mph. Increased speeds would be expected to result in increased stopping distances and an annual increase of between 6 and 18 fatalities and between 171 and 405 injuries. Further, injuries would likely be more severe as a result of the higher speeds traveled. If the average speed continues to increase in the long run, or if higher speeds spill over onto the urban interstate highway system or rural collector roads, then additional injuries and fatalities would be expected on those systems as well. On the other hand, the primary quantifiable benefit of the higher limit would be a savings of 1.3 million hours in business and commercial travel time. This study has also found that almost 60% of the Virginians surveyed would prefer a 65 mph speed limit to a 55 mph limit on the rural interstate highway system. Finally, because of the current speeds, the geometric design, and the accident history of the rural interstates in general, it would be possible to raise the speed limit without violating traffic engineering tenets for setting speed limits. However, if the speed limit is raised, establishing a truck speed limit differential below the limit established for passenger cars would promote increased speed variance between cars and trucks, thereby creating a more dangerous environment than if the speed limit were raised to the same level for both cars and trucks.

Author: Nicholas J. Garber
Publisher:
ISBN:
Category : Traffic accidents
Languages : en
Pages : 38

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Book Description
Although considerable progress has been made over the past several years in making highway travel safer, the frequency and severity of speed-related crashes on the nation's highways continue to be of concern. Understanding the factors associated with these crashes enables engineers to identify and implement effective countermeasures to reduce the probability of crashes. A number of studies have been conducted to determine the variation of crash rates as they relate to hourly traffic volumes, geometric characteristics, average speed, and speed variance. However, these studies have not established mathematical relationships that can be used to estimate changes in the crash characteristics as a result of the combined changes in speed, flow, and geometric characteristics. The establishment of direct mathematical models that describe the influence of these factors on crash characteristics would significantly enhance the efforts of traffic engineers to determine suitable countermeasures to reduce the occurrence and severity of crashes. This project develops mathematical relationships that describe the combined influence that traffic and geometric characteristics have on crash occurrences. This study was limited to roadways in the state of Virginia with speed limits of 89 or 105 km/h (55 or 65 mph). The data were obtained from speed monitoring stations established by the Virginia Department of Transportation (VDOT) and from police accident reports from January 1993 to September 1995. Using the variables of mean speed, standard deviation of speed, flow per lane, lane width, and shoulder width to predict crash rates, different types of deterministic models, such as multiple linear regression, robust regression, and multivariate ratio of polynomials were fitted to the data. The multivariate ratio of polynomials was found to be the only mathematical model type that was successful in describing any relationship between the combined effects of changes in the speed, flow, and geometric characteristics of the road on crash rates. Based on this study, all of the models show that under most traffic conditions, the crash rate tends to increase as the standard deviation of speed increases. The effect of the flow per lane and mean speed on the crash rate varied with respect to the type of highway.