Speed Limit Change (55 Mph to 60 Mph) Safety Re-evaluation PDF Download
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Author: Richard Storm Publisher: ISBN: Category : Speed limits Languages : en Pages : 0
Book Description
The objective of this study was to evaluate the safety impacts of increasing the speed limit from 55 mph to 60 mph on two-lane, two-way state highway road segments in Minnesota. An empirical Bayes (EB) before-after analysis was used to estimate crash modification factors (CMFs) for both segments and intersections. The segment analysis showed an 8 percent reduction in total crashes that was statistically significant, alongside a significant 15 percent increase in combined fatal, serious injury, and minor injury (KAB) injury crashes. The range of most of the segment CMFs hovered close to 1. The intersection analysis was split into two groups (all traffic control types and thru-stop control only). The aggregate CMFs for all intersections within these two groups showed, on average, between a 10% and 20% statistically significant reduction in total and injury crashes. Analysis was also performed on four subgroups (3- and 4-leg, lighting/no lighting) within the two main intersection groups. Disaggregating the intersections into further groups led to smaller sample sizes that led to higher standard errors showing a widespread range of CMFs around 1 for the individual crash types and severities. The aggregate estimated crash safety effects (for total and injury crashes) for combined segments and intersection sites showed a reduction in total crashes but an increase in the KAB injury crashes.
Author: Richard Storm Publisher: ISBN: Category : Speed limits Languages : en Pages : 0
Book Description
The objective of this study was to evaluate the safety impacts of increasing the speed limit from 55 mph to 60 mph on two-lane, two-way state highway road segments in Minnesota. An empirical Bayes (EB) before-after analysis was used to estimate crash modification factors (CMFs) for both segments and intersections. The segment analysis showed an 8 percent reduction in total crashes that was statistically significant, alongside a significant 15 percent increase in combined fatal, serious injury, and minor injury (KAB) injury crashes. The range of most of the segment CMFs hovered close to 1. The intersection analysis was split into two groups (all traffic control types and thru-stop control only). The aggregate CMFs for all intersections within these two groups showed, on average, between a 10% and 20% statistically significant reduction in total and injury crashes. Analysis was also performed on four subgroups (3- and 4-leg, lighting/no lighting) within the two main intersection groups. Disaggregating the intersections into further groups led to smaller sample sizes that led to higher standard errors showing a widespread range of CMFs around 1 for the individual crash types and severities. The aggregate estimated crash safety effects (for total and injury crashes) for combined segments and intersection sites showed a reduction in total crashes but an increase in the KAB injury crashes.
Author: Taha Saleem Publisher: ISBN: Category : Speed limits Languages : en Pages : 53
Book Description
The objective of this study was to evaluate the safety impacts of increasing the speed limit from 55 mph to 60 mph on two-lane, two-way state highway road segments in Minnesota. An empirical Bayes (EB) before-after analysis was used to estimate crash modification factors(CMFs) for both segments and intersections. The segment analysis showed a 7 percent increase in total crashes that was statistically significant, alongside insignificant increases/decreases in injury and run-off-road and head-on crashes. The range of most of the segment CMFshovered close to 1 (essentially meaning that the crashes either remained unchanged or the change was minor). The intersection analysis was split into two groups (all traffic control types and thru-stop control only). The aggregate CMFs for all intersections within these two groups showed that most of the CMFs hovered close to 1. Analysis was also performed on four subgroups (3- and 4-leg, lighting/no lighting) within the two main intersection groups. Disaggregating the intersections into further groups led to smaller sample sizes that led to higher standard errors, showing a widespread range of CMFs around 1 for the individual crash types and severities. The aggregate analysis conducted using all the segment and intersection data showed a minor increase/decrease in the total and injury crashes. This aggregate result along with before-and-after operating speed data from another Minnesota Department of Transportation (2019) study showing that the 85th percentile operating speed remained the same and that mean operating speeds increased by 1 mph following the speed limit increase can lead to aconclusion that the speed limit increase from 55 mph to 60 mph had a very minor to no effect on total and injury crashes or operating speeds.
Author: United States. Congress. House. Committee on Science and Technology. Subcommittee on Transportation, Aviation, and Materials Publisher: ISBN: Category : Speed limits Languages : en Pages : 336
Author: American Association of State Highway and Transportation Officials. Operating Subcommittee on Traffic Engineering Publisher: ISBN: Category : Speed limits Languages : en Pages : 66
Author: Publisher: ISBN: Category : Government publications Languages : en Pages : 26
Book Description
An update is provided of key legislative changes that have taken place concerning the fifty-five miles-per-hour National Maximum Speed Limit (NMSL). Summary statistics through the 1978 time period are followed by summaries of the literature reviewed on the benefits of the NMSL. An annotated bibliography of 16 studies represents various points of view and interests of the traffic safety community, and a supplementary list of references is provided. Findings of the Task Force are presented with the range of estimates for conclusions drawn. Since the 1973-4 decreases in fatalities, travel, and speed, there have been small increases for 1976-8, but the level of fatalities has not returned to pre-55 mph NMSL levels. In spite of a shortage of reliable data, it was concluded that 20,000 to 30,000 lives were saved in the 1974-1978 period.
Author: Richard Storm
Author: Richard Storm
Author: Taha Saleem
Author: P. Johnson
Author: Terry M. Klein
Author: Ezio C. Cerrelli
Author: D. F. Mela
Author: United States. Congress. House. Committee on Science and Technology. Subcommittee on Transportation, Aviation, and Materials
Author: American Association of State Highway and Transportation Officials. Operating Subcommittee on Traffic Engineering
Author: 
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