Analysis of Rural Interstate Fatality Rates in Consideration of Recent Increases in Maximum Statutory Speed Limits

Warner, Jacob; Chawla, Hitesh; Zhou, Chao; Savolainen, Peter T.

doi:10.1177/0361198119851758

Cited by 6 publications

(2 citation statements)

References 12 publications

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“…However, the recent increase in regulatory speed limit to 75 mph on 600 mi of freeway in Michigan raises concerns on traffic safety and operations at these locations. Since the repeal of the 1974 NMSL, the majority of studies found that crash frequency and the number of fatalities increased as a result of speed limit increase (18)(19)(20)(21)(22). Research has shown speed limit increases to be associated with adverse impacts on the roadways where the limits were, as well as adjacent facilities or across the road network as a whole (4,23).…”

Section: Literature Reviewmentioning

confidence: 99%

Safety Evaluation of Freeway Exit Ramps with Advisory Speed Reductions

Megat-Johari

Savolainen

et al. 2022

Transportation Research Record: Journal of the Transportation R

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Posted speed limits inform drivers of the legal maximum allowable speed. In contrast, advisory speeds provide recommendations to drivers based on highway design, operating characteristics, and conditions. Various studies have investigated the safety impacts of speed limit changes, particularly on high-speed rural highways. One area of particular concern on such roadways is the approach to exit ramps that require substantive speed reductions, such as loop ramps. To date, there has been limited research examining the safety impact of the differential between the mainline speed limit and the lower exit ramp advisory speeds. This study aims to evaluate this relationship through the estimate of a series of safety performance functions. Random effects negative binomial regression models were estimated using data from 187 exit ramps where advisory speed signs are present throughout Michigan. The analyses were conducted based on a five-year period from 2014 to 2019, excluding 2017 data because of speed limit increases. In addition to speed differentials, various roadway characteristics such as deceleration lane length and curve radius were also evaluated. Results indicate that crashes increased as the difference between mainline and ramp speed increased. Crashes were also shown to decrease on ramps where the upstream deceleration lane length was greater than the minimum recommendation as per current design guidance.

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Section: Literature Reviewmentioning

confidence: 99%

Safety Evaluation of Freeway Exit Ramps with Advisory Speed Reductions

Megat-Johari

Savolainen

et al. 2022

Transportation Research Record: Journal of the Transportation R

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“…The extant research literature has generally shown that the fatalities are consistently higher among states with higher maximum statutory speed limits (Warner et al 2019;Davis et al 2015). However, various states have recently increased or are planning to increase their maximum speed limits since (Donnell et al 2016).…”

Section: Study Objectivementioning

confidence: 99%

How is traffic safety affected by changes in traffic speeds following speed limit increases? An evaluation with probe vehicle data

Gupta

Megat-Johari

Jashami

et al. 2022

TSR

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Maximum speed limits continue to be an important policy issue. Research has consistently shown speeds to increase following speed limit increases. These increases have also generally coincided with increases in both the frequency and severity of crashes. However, research has been more limited as to the direct relationship between speed and safety. To this end, the present study evaluates the effects of increasing speed limits on the safety of rural limited access freeways while accounting for contemporaneous changes in the speed profiles of these same roadways. The speed limit increases in Michigan occurred between May 1 and June 12 of 2017, when the maximum speed limits were increased from 70 to 75 mph on approximately 600 miles of freeways. The maximum speed limits for trucks were also increased from 60 to 65 mph on all freeways state-wide at this same time. Speed data were obtained for the Michigan rural freeway network through probe vehicles. These data are merged with pertinent roadway data, as well as police-reported crash data at various levels of injury severity. The impacts of the speed limit increase on safety were evaluated by estimating random effects negative binomial models as part of a case-control before-after study design. The results show that the locations where the speed limits were increased experienced a 5% increase in crashes, while a marginal reduction in crashes was observed where speed limits did not increase. Interestingly, mean speeds were found to be negatively associated with crash frequency, while the standard deviation of speed was found to exhibit a positive relationship. Several site-specific characteristics were also found to be strong predictors of crash frequency. The results provide important insights into the nature of the relationship between speed and safety and will help to guide subsequent speed limit policy decisions.

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Does the 80 km/h speed limit save lives in France?

Carnis,

Garcia

2024

Journal of Safety Research

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Analysis of Rural Interstate Fatality Rates in Consideration of Recent Increases in Maximum Statutory Speed Limits

Cited by 6 publications

References 12 publications

Safety Evaluation of Freeway Exit Ramps with Advisory Speed Reductions

Safety Evaluation of Freeway Exit Ramps with Advisory Speed Reductions

How is traffic safety affected by changes in traffic speeds following speed limit increases? An evaluation with probe vehicle data

Does the 80 km/h speed limit save lives in France?

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