Speed Characteristics in Relation to Speed Limit Increase and Its Influence on Driver’s Speed Selection Behavior

Reza S Shirazinejad,Sunanda Dissanayake

doi:10.3390/su12041369

Reza S Shirazinejad, Sunanda Dissanayake

Open Access

https://doi.org/10.3390/su12041369

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Abstract

Speed is a quality measurement for travel, since it is related to traffic, safety, time, and economics. The speed limit on selected freeways in Kansas changed from 70 mph to 75 mph in the summer of 2011. In this study, the driver’s speed selection behavior was analyzed by considering average speed and 85th percentile speed in the before and after periods. Data from Automatic Traffic Recorders (ATRs) on the sections affected by speed limit increase and sections with no speed limit increase were analyzed. The t-test was applied to investigate if there was any significant difference in the speed of drivers on both treated and control sections. The Kolmogorov-Smirnov (K-S) test was also conducted to see if the distribution of speed data in the before period was different than after the period. The results showed that for the majority of the sections affected by speed limit change, there was a statistically significant difference in the 85th percentile speed of drivers during after period. Additionally, the K-S test results showed that the distribution of speed data in the before period was different than after the period for the majority of treated sections. The results indicated how drivers’ behavior was influenced by the speed limit increase.

Highlights

IntroductionExceeding the speed limit and driving too fast for conditions is one of the traffic violations that often happens on the roads
Speeding is a common habit for drivers
The statistically significant difference between before and after the period for all of the sections is due to the large sample size in this research, that any change in 85th percentile speed would be significant as recognized by previous research as well [10]

Summary

Introduction

Exceeding the speed limit and driving too fast for conditions is one of the traffic violations that often happens on the roads. In 2011, Kansas legislature passed the new maximum speed limit law on selected segments of freeways. It was thought that drivers were already driving 5–10 miles above the posted speed limit and it made sense to make it formal. Speed limit increase was expected to help the economic development of Kansas, via travel time savings. Opponents were saying that drivers would not change their behavior and would drive 5–10 miles more than the new posted speed limit, where higher speed might negatively influence safety and may increase the number and severity of crashes [1]

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Conclusion