Praveena Penmetsa

Risk drivers pose to themselves and other drivers by violating traffic rules

ABSTRACT Objective: Violation of traffic rules is a major contributing factor in both crashes and fatalities in the United States. This study aims at quantifying risk that drivers pose to themselves and other drivers by violating traffic rules. Method: Crash data from 2010 to 2013 were gathered for the state of North Carolina. Descriptive analysis was carried out to identify frequent traffic violations and who were committing the traffic violations that resulted in crashes. A multinomial logit model was then developed to examine the relation between different traffic violations and driver injury severity. Additionally, odds ratios were estimated to identify the likelihood (probability) of severe or moderate injury to the driver and other drivers due to a driver violating a traffic rule that led to a crash. Results: Exceeding the speed limit is more likely to result in severe injury compared to disregarding traffic signals. However, going the wrong way is more likely to result in severe injury to other drivers when compared to any other traffic violation. Driving under the influence of alcohol is 2 times more likely to result in severe injury than driving under the influence of drugs. These 2 traffic violations by a driver are almost equally likely to result in severe injury to other drivers. Conclusions: Drivers often perceive that violating traffic rules will not result in a crash or severe injury. However, the results from this study show that a majority of the traffic violations lead to severe injury to the violator as well as to other drivers. The findings from this study serve as documented evidence to educate drivers about the risk they pose to themselves and to other drivers by violating traffic rules and encourage the adaptation of safe driving behavior in order to contribute toward reaching the “zero traffic deaths” vision. They also help make policy changes pertaining to penalty points and fines for violating a traffic rule.

Methods to rank traffic rule violations resulting in crashes for allocation of funds

Education, enforcement and engineering countermeasures are implemented to make road users comply with the traffic rules. Not all the traffic rule violations can be addressed nor countermeasures be implemented at all unsafe locations, at once, due to limited funds. Therefore, this study aims at ranking the traffic rule violations resulting in crashes based on individual ranks, such as 1) frequency (expressed as a function of the number of drivers violating a traffic rule and involved in crashes), 2) crash severity, 3) total crash cost, and, 4) cost severity index, to assist transportation system managers in prioritizing the allocation of funds and improving safety on roads. Crash data gathered for the state of North Carolina was processed and used in this study. Variations in the ranks of traffic rule violations were observed when individual ranking methods are used. As an example, exceeding authorized speed limit and driving under the influence of alcohol are ranked 1st and 2nd based on crash severity while failure to reduce speed and failure to yield the right-of-way are ranked 1st and 2nd based on frequency. To minimize the variations and capture the merits of individual ranking methods, four different composite ranks were computed by combining selected individual ranks. The computed averages and standard deviations of absolute rank differences between composite ranks is lower than those obtained from individual ranks. The weights to combine the selected individual ranks have a marginal effect on the computed averages and standard deviations of absolute rank differences. Combining frequency and crash severity or cost severity index, using equal weights, is recommended for prioritization and allocation of funds.

Modeling Crash Injury Severity by Road Feature to Improve Safety

ABSTRACT Objective: The objective of this research is 2-fold: to (a) model and identify critical road features (or locations) based on crash injury severity and compare it with crash frequency and (b) model and identify drivers who are more likely to contribute to crashes by road feature. Method: Crash data from 2011 to 2013 were obtained from the Highway Safety Information System (HSIS) for the state of North Carolina. Twenty-three different road features were considered, analyzed, and compared with each other as well as no road feature. A multinomial logit (MNL) model was developed and odds ratios were estimated to investigate the effect of road features on crash injury severity. Results: Among the many road features, underpass, end or beginning of a divided highway, and on-ramp terminal on crossroad are the top 3 critical road features. Intersection crashes are frequent but are not highly likely to result in severe injuries compared to critical road features. Roundabouts are least likely to result in both severe and moderate injuries. Female drivers are more likely to be involved in crashes at intersections (4-way and T) compared to male drivers. Adult drivers are more likely to be involved in crashes at underpasses. Older drivers are 1.6 times more likely to be involved in a crash at the end or beginning of a divided highway. Conclusions: The findings from this research help to identify critical road features that need to be given priority. As an example, additional advanced warning signs and providing enlarged or highly retroreflective signs that grab the attention of older drivers may help in making locations such as end or beginning of a divided highway much safer. Educating drivers about the necessary skill sets required at critical road features in addition to engineering solutions may further help them adopt safe driving behaviors on the road.

Examining Injury Severity of Not-At-Fault Drivers in Two-Vehicle Crashes

The focus of this paper is to examine the injury severity of not-at-fault drivers in two-vehicle crashes. North Carolina crash data collected from 2009 to 2013 were used for the analysis. Ordered probit model was initially chosen because of the ordinal nature of the dependent variable (injury severity of the driver not at fault). However, the data failed to obey the proportional odds assumption accompanied with the ordered probit model. Therefore, a partial proportional model was fitted for two-vehicle crashes. Compared with the physical condition of at-fault drivers, the physical condition of not-at-fault drivers had a greater effect on the severity of injury to the not-at-fault drivers. Exceeding the speed limit, aggressive or reckless driving, and going the wrong way are the three traffic rule violations of at-fault drivers that are more likely to result in severe injuries to not-at-fault drivers than disregarding traffic signs, signals, and markings. Similarly, a crash involving an at-fault driver with violations of two and three traffic rules is 1.68 and 2.86 times likely to result in severe injuries to not-at-fault drivers compared with a crash involving an at-fault driver with only one traffic rule violation. Motorcyclists are observed to be at highest risk with the odds of severe injury to motorcyclists who are not at fault. Crashes with female at-fault drivers are less likely to result in severe injury to the not-at-fault drivers. Female drivers are also more likely to be severely injured when they are not at fault.

Illustrating the Monetary Impact of Transportation Projects/Alternatives using the Values of Travel Time and Travel Time Reliability

State agencies, regional agencies, cities, towns, and local municipalities design and maintain transportation systems for the benefit of users by improving mobility, reducing travel time, and enhancing safety. Cost–benefit analysis based on travel time savings and the value of reliability helps these agencies in prioritizing transportation projects or when evaluating transportation alternatives. This paper illustrates the use of monetary values of travel time savings and travel time reliability, computed for the state of North Carolina, to help assess the impact of transportation projects or alternatives. The results obtained indicate that, based on the illustration of the effect and impact of various transportation projects or alternatives, both improved travel time and reliability on roads yield significant monetary benefits. However, from cost–benefit analysis, it is observed that greater benefits can be achieved through improved reliability compared with benefits from a decrease in travel time for a given section of road.

Risk factors attributed to fatal fixed-object crashes on noninterstate roads

ABSTRACT This study aims at identifying risk factors attributed to fatal fixed-object crashes on noninterstate roads. Logistic regression modeling was used to understand the relation or extent of the effect of selected independent variables on fatal fixed-object crashes on noninterstate roads. A total of 30 independent variables were considered in this study. At a 95% confidence interval, nine independent variables were found to play a statistically significant role on fatal fixed-object crashes on noninterstate roads. The probability of getting involved in a fatal fixed-object crash on noninterstate roads with full access control is lower compared to noninterstate roads with no access control. Rolling terrain reduces the probability of getting involved in a noninterstate fatal fixed-object crash. Older drivers are more likely to be killed in a noninterstate fatal fixed-object crash. Drivers under the influence of alcohol are four times more likely to be killed in a noninterstate fatal fixed-object crash compared to a sober driver. The findings from this study provide adequate evidence and assist traffic engineers and policy makers to better understand the role of risk factors and identify suitable countermeasures to reduce fatal fixed-object crashes specifically on noninterstate roads.