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: Ezio C. Cerrelli Publisher: ISBN: Category : Highway law Languages : en Pages : 86
Book Description
The report estimates the increase in the number of motor vehicle accidents, injuries and fatalities that would result from an increase in the national speed limit to 60 mph. The report makes use of available travel and accident statistics, adopts previously identified relationships between travel speeds and accidents, and relies on a stated set of assumptions. The major conclusion of the report is that raising the speed limit to 60 mph will result in an increase of approximately 3500 fatalities per year, thus offsetting most of the safety benefits experienced under the 55 mph speed limit. The report provides estimates for the year 1977, which was selected solely for the purpose of exercising the model. However, the same model can be utilized in a similar fashion to arrive at estimates for any future year for which both traffic and safety conditions can be forecasted.
Author: American Association of State Highway and Transportation Officials. Operating Subcommittee on Traffic Engineering Publisher: ISBN: Category : Speed limits Languages : en Pages : 66
Author: United States. National Highway Traffic Safety Administration. Enforcement and Emergency Services Division Publisher: ISBN: Category : Languages : en Pages : 60
Author: Richard Storm
Author: Richard Storm
Author: Taha Saleem
Author: Terry M. Klein
Author: P. Johnson
Author: D. F. Mela
Author: Ezio C. Cerrelli
Author: Ezio C. Cerrelli
Author: American Association of State Highway and Transportation Officials. Operating Subcommittee on Traffic Engineering
Author: United States. National Highway Traffic Safety Administration. Enforcement and Emergency Services Division
Author: