Author: Robert D. McMillenPublisher:
ISBN:
Category : Speed limits
Languages : en
Pages :
Book Description
"The Effect on Traffic Operation of Increasing Speed Limits on an Interstate Route"
Author: Robert D. McMillenPublisher:
ISBN:
Category : Speed limits
Languages : en
Pages :
Book Description
The Effect of Increased Speed Limits in the Post-NMSL Era
Author: United States. National Highway Traffic Safety AdministrationPublisher:
ISBN:
Category : Speed limits
Languages : en
Pages : 92
Book Description
Effects of the 55 Mph Speed Limit
Author: American Association of State Highway and Transportation Officials. Operating Subcommittee on Traffic EngineeringPublisher:
ISBN:
Category : Speed limits
Languages : en
Pages : 66
Book Description
Interim Report on the Safety Consequences of Raising the Speed Limit on Rural Interstate Highways
Author: Managing Speed
Author: Publisher: Transportation Research Board
ISBN: 9780309065023
Category : Business & Economics
Languages : en
Pages : 444
Book Description
TRB Special Report 254 - Managing Speed: Review of Current Practices for Setting and Enforcing Speed Limits reviews practices for setting and enforcing speed limits on all types of roads and provides guidance to state and local governments on appropriate methods of setting speed limits and related enforcement strategies. Following an executive summary, the report is presented in six chapters and five appendices.
Safety Impacts of Different Speed Limits on Cars and Trucks
Author: David L. HarkeyPublisher:
ISBN:
Category : Speed limits
Languages : en
Pages : 78
Book Description
The objectives of this study were to determine whether differential or uniform speed limits are more beneficial to transportation safety and traffic operations on Interstate highways. The approach to achieving this objective was to examine speed and accident data from States employing both types of limits. Speed data were collected in 12 States at rural and urban locations representing all speed limits currently established on the Interstate highway system for cars/trucks, i.e., 55/55 mi/h (89/89 km/h), 65/55 mi/h (105/89 km/h), 65/60 mi/h (105/97 km/h), and 65/65 mi/h (105/105 km/h). Accident data were obtained from nine States which were geographically distributed across the country and representative of all rural Interstate speed limits currently established. For the speed data collected, a number of measures of effectiveness (MOEs) were examined including mean speed, speed variance, compliance, and speed distribution measures. For the accident data collected, types of crashes were examined (e.g., rear-end) along with vehicle type involvement (e.g., car-into-truck) and crash severity. This final report summarizes the effects of uniform and differential speed limits on transportation safety and traffic operations as determined by the examination of speed and accident data.
Impacts of Freeway Speed Limit on Safety and Operation Speed of Adjacent Arterial Roads
Author: Fadi Abdallah AlhomaidatPublisher:
ISBN:
Category : Automobile drivers
Languages : en
Pages : 203
Book Description
Urban arterials carry the most traffic on urban road networks and experience the highest percentage of crashes in urban areas. Safety on the lower speed urban arterials that are adjacent to a higher speed freeway may be impacted by speed spillover or adaptation. In this context, speed spillover is defined as the tendency of drivers to speed on the lower speed facility after exiting the higher speed facility. The objective of this research is to investigate drivers' speed choices and the relationship between speed and crashes on urban arterials adjacent to freeways. The study also examines potential countermeasures for speeding behavior in the area under the speed spillover effect. To determine the effect of freeway speed limits on speed spillover, analysis was performed using two types of speed data: (1) point (i.e., spot speed) and (2) trajectory (i.e., continuous trip time series). While spot speed data were collected using a radar technology, the trajectory data were gathered from around 2,700 vehicles equipped with connected vehicle technologies and acquired from Intelligent Transportation System Research Data Exchange - Safety Pilot Model Deployment (SPMD) roadside equipment. Comparison of speed differences between motorists who exited the freeway and those who were already driving on the arterial road was performed. Results showed that the mean speed and the 85th percentile speed of vehicles exiting from the 70 mph freeway are significantly higher when compared to the vehicles that were already driving on the arterial road. The effect of raising freeway speed limits to 70 mph on the frequency of speed-related crashes on urban arterial roads adjacent to freeways (i.e., spillover effects) was investigated. Crash data were collected from Michigan on 1,393 road segments of urban arterials before and after speed limits were altered. Before-and-after data was collected simultaneously on 1,470 comparison segments of urban arterial where speed limits did not change to control for the regression-to-the-mean bias. The mixed effects negative binomial (MENB) regression model was developed to analyze crash frequency. The results indicate that raising speed limits of freeways by as much as five miles per hour had a likelihood of increasing crash frequency on adjacent arterial roads by as much as 13.9 percent. This increment in crashes observed on arterial roads involved more different crash types comparing to those that occurred on freeway. There exist more potential motorist-to-motorist conflicts as well as motorist-to-other road users (e.g., pedestrians and bicyclists) on arterial roads than on freeways. Therefore, the potential for a speeding vehicle to collide with another vehicle or other road user is higher on urban arterials. To investigate if the safety impact of speed spillover changes with the distance from the freeway, influence areas (0-1 mile, 1-2 mile, and 2-3 mile) were used. Speed-related crashes were impacted more on the 0-1 mile and the 1-2 ranges by 41.1 percent and 17.5 percent, respectively, compared to the 2-3 mile range. The study finds that the influence of freeway speed on drivers' speeding behavior on adjacent urban arterials fades away as the distance from the freeway increases. To mitigate speed spillover, a driving simulator study was used to investigate potential countermeasures for speeding behavior. The study observed the behavior of 56 participants who drove a 5300 meters section of freeway, then exited to a two-mile urban arterial. The driving simulator results were validated using field data collected from trajectory speed data. The impact of Crash Fact Sign (CFS), a message that provides information about the number of crashes/fatalities that occurred on that particular road, and Warning Sign (WS) on areas under the speed spillover influence were studied. Each participant was asked to drive under a base scenario (without any countermeasure) and four test scenarios, namely(1) an additional speed limit sign (SLS-2); (2) Warning Sign (WS); (3) Crash Fact Sign (CFS); and (4) Crash Fact Sign With additional Speed Limit Sign (CFS&SLS-2). The study finds CFS&SLS-2 to be the most effective countermeasure because it produces significant speed reductions in the area under speed spillover effect. Furthermore, the effect of a traffic signal on speed spillover behavior was investigated. Speed spillover effect existed for longer distance when drivers did not stop at the signalized intersection compared to when drivers stopped. This study provides researchers, policymakers, law enforcement officials, and engineers with a better understanding of the effects of speed spillover on adjacent roads when determining whether to increase the speed limit on freeways. The study suggests that urban arterial segments adjacent to high speed freeways need more attention in terms of speeding countermeasures. It also recommends potential effective countermeasures for speeding.
The Safety Impacts of Increasing the Speed Limit to 70 MPH in the State of Wisconsin
Author: Kirsten L. BrosePublisher:
ISBN:
Category : Speed limits
Languages : en
Pages : 0
Book Description
The U.S. Department of Transportation's National Highway Traffic Safety Administration determined in May 2014 that the social and economic burden of vehicle crashes in 2010 cost the United States $836 billion dollars (1). Several factors play a role in this price tag, one of which is speed. The United States has undergone several significant nationwide modifications to speed limit restrictions throughout its history. These changes include the 1974 National Maximum Speed Law which mandated a top posted speed of 55 mph, the 1987 Surface Transportation and Uniform Relocation Act which allowed states to increase speeds to 65 mph and the 1995 National Highway System Designation Act which gave speed limit authority back to individual states. Today, only 7 states maintain a 65 mph speed limit (including Hawaii which has the nation's lowest maximum speed limit at 60 mph). Some states increased posted highway speeds to as high as 80 mph, including Texas which now has posted speed limits as high as 85 mph. On May 20, 2015, Wisconsin became the last Midwestern state to increase posted speed limits on select Interstate highways to 70 mph. The first changes occurred on 14 select roadway segments across the state, and since then, several other segments of Interstate highway have been increased as well. The increase in speed limit has brought with it great concern that the higher speeds will correlate to more dangerous high speed driving, higher incident rates, greater fatalities on the roadway and an overall more dangerous driving environment. Through the application of two WisTransPortal web applications; the MV4000 crash database and the VSPOC (Volume, Speed and Occupancy) Traffic Detector database these concerns were evaluated by analyzing incidents, traveled speeds and roadway volumes. The posted speed limit increase occurred in mid-June of 2015 across the state of Wisconsin. Therefore, the analysis of this research focused on data from July through December of the calendar years 2005 to 2015. This allowed for 14 years of data prior to the increase in speed limit to be compared to the most recent one year of data post speed limit increase, maintaining the same monthly duration to allow for consistency. The research looked at comparing total incidents occurring on the 14 routes, as well as fatal incidents, alcohol related incidents and speed related incidents. The presumption that a 5 mph posted speed limit increase directly correlates to a 5 mph operating speed increase was also evaluated. This analysis was performed by randomly selecting eight days throughout the year and comparing the average operating speed before and after the June 2015 posted speed limit increase. Additionally the two datasets were combined to study incidents per thousand vehicles on the roadway. In the first five months after the posted speed increase to 70 mph, it was determined that the higher speed limit did not show a statistically significant increase in the total number of incidents occurring on the segments of roadway increased to 70 mph. Additionally, those routes showed an increase in operating speed of 1.5 mph, well below the posted speed limit increase of 5 mph. Incidents per thousand vehicles on the roadway was also statistically lower in 2015, when the posted speed was increased to 70 mph. As of January 1, 2016, it can be concluded that the increase in posted speed limit to 70 mph has not led to a greater number of crashes on the Interstate highways in the state of Wisconsin. Additionally, average operating speeds have increased by 1.5 mph, well below the 5 mph posted speed increase.
Impact and Implementation of the 55-mile-per-hour Speed Limit
Author: United States. Congress. House. Committee on Public Works and Transportation. Subcommittee on Surface TransportationPublisher:
ISBN:
Category : Speed limits
Languages : en
Pages : 878
Book Description
Highway Safety and the 65 MPH Maximum Speed Limit
Author: Patrick S. McCarthyPublisher:
ISBN:
Category : Speed limits
Languages : en
Pages : 72
Book Description