Traffic Safety California State University, Stanislaus Traffic Safety Throughout the last quarter of a century, California has reduced and increased the maximum speed limit on all the highways. In 1974, the maximum speed limit on all California highways was reduced from 65 miles per hour to 55 miles per hour. By 1988 the state of California decided to increase the speed limit on some highways to 65 miles per hour. During the year of 1996 the state of California increased the speed limit again, to 70 miles per hour, affecting the majority of the rural interstates and rural portions of Highway 99 and 215. States throughout the country have enacted similar law changes regarding speed limits.
These speed limit changes caught the interest of many researchers, causing them to conduct research regarding the positive and negative effect of such changes. After reviewing past researches, I predict traffic safety on highways will see an increase in crash rates where there are increase speed limit. I also predict there will be no significant gender differences in male and female drivers when it comes to the effect of speed limit law changes.
The following researches, analyzes traffic safety about the effect of speed limit increases and whether these effects differ for male drivers and female drivers. Ossiander and Cummings (2002) were interested in determining the affect of speed limit increase instituted on the freeway in the state of Washington in the year of 1987 and traffic casualties. From 1970 through 1994 data was collected by the Washington State Department of Transportation and was given to the Washington State Traffic Safety Commission. Using the data obtained, Ossiander and Cummings analyzed the findings using poisson regression to examine the relationship between the fatal crash rate and the speed limit increase on rural and urban interstate freeways. Based on the data given, Ossiander and Cummings were able to suggest that, after the speed limit increase in 1987, fatal crash rate were substantially higher than prior years in rural area interstate freeways. The average speed also increased in rural areas where there were speed limit increases. Crash rate had no significant changes on any interstate freeway.
Urban area interstate freeway also had no changes. Vernon, Cook, Peterson, and Dean (2004) were interested in analyzing the effects of the speed limit increase in the state of Utah correlating with crash, injury, and death rates. The repeal of the national maximum speed limit law in 1995 allowed an increase in speed limits in Utah and other states. Data from 1992 through 1999 were available to be acquired from Utah Department of Transportation and were reported as average annual daily traffic. The average annual daily traffic was then converted to traffic volume of every 100 million vehicles miles traveled on the highways of Utah.
All road segments that had an increase in speed limit were included but were analyzed separately into Interstate and non-Interstate highways. Interstate with speed increase in urban areas of Utah had a considerable rise in crash rate but no significant increase was found in fatalities or injuries. Rural interstate highways, with speed limit increases reported no significant changes in injury, crash, or fatality rate. On Non-Interstate highways of Utah an increase in fatalities had risen after the speed limits were increased but crash and injuries had no rate changes. Tornros (1995) studied the effects of driving speed of 70, 90 and 110 kilometer per hour on subsidiary auditory reaction time while driving a car on a motorway with a speed limit of 110 kilometer per hour.
Twenty-four healthy participants ranging from the ages of twenty to forty-three with a driver license was selected to participate in a study-involving car driving tasks. Participants??™ have had their driver license ranging from 1 year to 15 years. Of the twenty-four participants eighteen were males and six were females. They were instructed to drive a distance of 200 kilometers, maintain a constant speed of 70 kilometers per hour, 90 kilometers per hour, and 110 kilometers per hour, to pass the vehicle in front at a moment notice and to react as rapidly as possible to a sound signal by getting to the extra pedal on the floor. Prior to the actual driving test, participants were given a simulation of the test at a distance of 40 kilometers.
The researcher collected their data before, after and during the driving task. They recorded participants??™ reaction time in milliseconds and reaction time driving the car in minutes while driving each distance. Participants were then to rate their mood and arousal, along with ranking their experience of sleepiness and tiredness. Reaction time was found to be slower when compared to the driving speed of 70 kilometers per hour than at 110 kilometer per hour. There was no after-effect of speed factor presented in the before and after car driving tasks. Results showed participants felt more energetic and less tired towards the end of the task while driving at 110 kilometers per hour compared to 70 kilometers per hour. Warshasky-Livne and Shinar (2002) wanted to assess variables that may affect brake-movement time between the accelerator pedal and the brake pedal. Seventy-two participants ranging in age of 18 to 82 with a driver license of at least 1 year of experience were separated evenly into three different age categories.
The categories consisted of ages between 18 through 25, 26 through 49 and 50 through 82. Each group of 24 had 12 male participants. Of the 12 male participants, six of them either drove an automatic or manual transmission. Participants each performed ten trials in a driving simulator of three uncertainty conditions while researchers??™ recorder their reaction time and brake-movement time. Perception-reaction time is the time between the light onset and the first movement of the foot on the accelerator and not the actual release of the foot from the pedal.
Brake-movement is the time the first movement of the foot from the accelerator and the contact with the brake pedal. As a result, the type of transmission had no significant effect on either reaction time. But when there were increased uncertainties, participants??™ perception reaction time increased while there were no increases in brake movement time.
Males were slower in brake movement reaction time compared to females (males 0.19 s vs. females 0.16 s). There were no gender differences in perception-reaction time.
This study has theoretical and practical implications. Concerns are about the relationship between reaction time and brake-movement time that determines braking time. Understanding the braking time and ways to reduce the time is crucial to ensure safe driving. In 2006 the state of Texas approved the establishment of speed limit increase of 80 miles per hour during daytime hours. Richard Retting and Ivan Cheung (2008) conducted an examination of traffic speeds before and after the new posting of 80 miles per hour on rural interstates in Texas Route 385, Interstate 10, and Interstate 20. 16 months after the speed limit increase, the average driving speed on Interstate 20 increased by 9 miles per hour. Route 385 is a road segments that had no speed limit increase, experienced a decline in average traffic speed. Interstate 10 experienced an increase of 4 miles per hour.
Even though this study did not evaluate crash outcomes, prior studies have found that increases in speed limits on interstate highways are associated with increases in motor-vehicle occupant fatalities. Traffic safety is a great concern when speed law is considered for changes. Based on my review between Ossiander and Cummings??™ (2002) studies with Vernon, Cook, Peterson, and Dean (2004), I concluded that each study have conflicting results. Ossiander and Cummings??™ (2002) study resulted in a higher fatal crash rate in only rural area of the interstate freeways in Washington and no significant changes in urban area interstate freeway.
Vernon, Cook, Peterson, and Dean (2004) study showed no significant changes rural interstate highways in Utah. Changes in crash rate were not necessarily related to the increase in speed limits and there were also no significant gender differences in between male and female drivers were found due to the effect of speed limit law changes.ReferencesOssiander, E. M., & Cummings, P. (2002). Freeway speed limits and traffic fatalities in Washington State. Accident Analysis and Prevention, 34, 13-18.
doi:10.1016/S0001-4575(00)00098-1Retting, R., & Cheung, I. (2008).
Traffic speeds associated with implementation of 80 mph speed limits on West Texas rural interstates. Journal of Safety Research, 39, 529-534. doi:10.1016/j.jsr.
2008.08.005Tornros, J. (1995). Effect of driving speed on reaction time during motorway driving.
Accident Analysis and Prevention, 27, 435-442. [pic]doi:10.1016/0001-4575(94)00084-YVernon, D.
D., Cook, L. J.
, Peterson, K. J., & Dean, J.M.
(2004). Effect of repeal of the national maximum speed limit law on occurrence of crashes, injury crashes, and fatal crashes on Utah highways. Accident Analysis and Prevention, 36, 223-229. doi:10.
1016/S0001-4575(02)00151-3Warshawsky-Livne, L., & Shinar, D. (2002). Effects of uncertainty, transmission type, driver age and gender on brake reaction and movement time. Journal of Safety Research, 33, 117-128.