The relationship between travel speeds, infrastructure characteristics, and crashes on two-lane highways (original) (raw)
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An Impact of Traffic Characteristics on Crash Frequency
E3S Web of Conferences
With the development of roads, modes of transportation were also developed, and increasing numbers of those modes and routes were needed. This increase brought into focus many problems of the highway system. One of the most important concerns in the highway networks is road safety, which requires various studies to be carried out to reduce crash causalities. One of the factors that affect road safety is the traffic characteristics. This includes average daily traffic, operating speed, traffic density, and heavy vehicles percentage. This study focused on the effect of average daily traffic and heavy vehicles percentage on crash frequency. The old Baghdad – Baquba rural road, a two-lane, two-way road, was chosen for this study. This study used two sets of data (traffic characteristics and crash data). Generalized linear regression models were utilized to develop a model that reflects the effect of the average daily traffic and heavy vehicles percentage on crash frequency. The results ...
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This study explored the relationship between travel speeds and accidents on single-carriageway roads, accounting for traffic exposure and road infrastructure characteristics. The speed data are free-flow travel speeds collected by GPS devices inside the vehicles. The study's database included 179 sections, in Israel. Negative binomial statistical models were fitted to injury accident counts, in day-and night-hours, using speed indicators, section length, traffic volume and homogeneous road groups, where road groups reflect various road design conditions. The models demonstrated a positive relation between mean speeds and accidents, while controlling for traffic exposure and road infrastructure characteristics.
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More than 60% of accidents in Iran occur within 30 kilometers of cities entrance roads. Therefore the number of accidents per kilometer in these regions, in contrast to the other parts of roads is very considerable. The city of Tehran, as the capital of Iran, is the cross point of major arterials of passenger and freight transportation. Thus the evaluation of road safety, entering and exiting the city in the 30 kilometers buffer, can be considered to improve countrywide road safety. To investigate the effects of roadway characteristics and traffic conditions, including number of traffic violations, on accident frequency within 30 km of Tehran entrance roads, Poisson and Negative Binomial regression model were calibrated in this study. Although the goodness of fit index in Poisson model is much greater than the Negative Binomial model, the accident data dispersion in this study implies that Negative Binomial model is more appropriate to show the influences of effective variables. Acc...
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An analysis of how various road infrastructure improvements affect traffic-related fatalities and injuries is conducted while controlling for other factors known to affect overall safety. The road infrastructure elements analysed include total lane miles, the fraction of lane miles in different road categories (interstates, arterial, and collector roads), the average number of lanes for each road category, and lane widths for arterials and collector roads. Other variables that are controlled for in the study include total population, population age cohorts, per capita income, per capita alcohol consumption, seat-belt legislation (and seat-belt usage), and a proxy variable that represents underlying changes in medical technology. The data used is a cross-sectional time series database of U.S. states and is analysed using a fixed effects negative binomial regression that accounts for heterogeneity in the data. Data from all 50 states over 14 years is used. Results strongly refute the hypothesis that infrastructure improvements have been effective at reducing total fatalities and injuries. While controlling for other effects it is found that demographic changes in age cohorts, increased seat-belt use, reduced alcohol consumption and increases in medical technology have accounted for a large share of overall reductions in fatalities.
Road accidents in India have risen to it toll in the last few decades. Con researchers in various part of the world have settled on the discussion of traffic safety management factor. An accident model has to be developed to establish the factors that cause the accidents. Accident model aids in determining the real cau of the accidents being witnessed across the country. The research article develops two accident models which are to be applied in various roads based on the location of the roads in the country such as in rural and urban roads. The main model mainly used in both rural and urban areas include linear and binomial distribution models. The data generated by several researchers indicates that the accidents in urban areas are attributed to age, speed, and gender. On the other hand, the ov speeding in rural roads has been noted the main cause of accidents Sumer 2003) [2, 12]. Vehicles, road conditions and human beings have an influence on the management of road safety. Investigation to establish the relationship between and the design of the roads has to be conducted. The main aim of the article is to establish the relationship between the accidents rates and the parameters employed in IJCIET/index.asp 441 Road accidents in India have risen to it toll in the last few decades. Con researchers in various part of the world have settled on the discussion of traffic safety An accident model has to be developed to establish the factors that cause the accidents. Accident model aids in determining the real cau of the accidents being witnessed across the country. The research article develops two accident models which are to be applied in various roads based on the location of the roads in the country such as in rural and urban roads. The main model mainly used in both rural and urban areas include linear and binomial distribution models. The data generated by several researchers indicates that the accidents in urban areas are attributed to age, speed, and gender. On the other hand, the ov speeding in rural roads has been noted the main cause of accidents (Ivan Vehicles, road conditions and human beings have an influence on the management of road safety. Investigation to establish the relationship between the accidents cases and the design of the roads has to be conducted. The main aim of the article is to establish the relationship between the accidents rates and the parameters employed in Road accidents in India have risen to it toll in the last few decades. Consequently, researchers in various part of the world have settled on the discussion of traffic safety An accident model has to be developed to establish the factors that cause the accidents. Accident model aids in determining the real causative agents of the accidents being witnessed across the country. The research article develops two accident models which are to be applied in various roads based on the location of the roads in the country such as in rural and urban roads. The main models which are mainly used in both rural and urban areas include linear and binomial distribution models. The data generated by several researchers indicates that the accidents in urban areas are attributed to age, speed, and gender. On the other hand, the over-Ivan et al. 2000; Vehicles, road conditions and human beings have an influence on the management the accidents cases and the design of the roads has to be conducted. The main aim of the article is to establish the relationship between the accidents rates and the parameters employed in The Statistical Analysis of Accident-Frequency Data: A Case Study of National Highway No 6 http://www.iaeme.com/IJCIET/index.asp 442 editor@iaeme.com the design. The article also develops models which are used in predicting accidents in both rural and urban roads (Mohan et al. 1985) [7].
Transportation Research Record: Journal of the Transportation Research Board, 2020
This paper explores the effects of operating speed and traffic flow on roadway safety in light of the methodology provided by the U.S. Road Assessment Program (usRAP). Unlike traditional approaches, usRAP produces a systemic expected roadway safety performance, more specifically the likelihood of being involved in a severe or a fatal crash, that is derived purely from roadway, roadside, and traffic characteristics, without need for detailed historical crash data. Data from over 7,000 mi of segments coded using the usRAP protocols and 5 years of crash data were used to examine changes in expected safety performance with changes in operating speed and traffic volumes. Speed and flow emerged as candidates for initial exploration as their effect is explicitly considered in the usRAP formulation for all crash types. The usRAP methodology indicated a gradual increase in the frequency of expected severe and fatal crashes with an increase in the operating speed, and such trends followed tho...
Injury, Fatal, and Property Damage Accident Models for Highway Corridors
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The relationship between fatal, injury, and property damage accident frequencies and traffic volume, segment length (SL), and vehicle miles traveled (VMT) is explored here. For this purpose, a generalized linear regression modeling framework was applied. Poisson, negative binomial, Gaussian, and log-normal distributions were evaluated in terms of their ability to model accident frequency for an interstate highway corridor in Colorado. Results indicate that, for injury, property damage, and total accidents, the Poisson regression with log-transformed predictors performed significantly better than the Poisson regression with linear predictors. For fatal accidents, the log-normal regression performed better than other regression models examined. However, the Poisson model performed better in terms of estimating accidents for the corridor. Models based on data disaggregated by median SL and annual average daily traffic (AADT) or VMT performed better than aggregated models. In addition, ...
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Different studies over the past 30 years have shown an increase in the rates of crash frequencies during road construction time, but this trend is not reported as valid for all cities. A question is raised whether higher rates are observed in arterial roads in Bogotá, Colombia. It is possible to apply descriptive statistics and hypothesis tests to prove them and identify the variables that affect the accident rate during road construction. Our research aims to verify the incidence of high impact construction zones, in the crash rate at the arterial road network of Bogotá. We use descriptive statistics and inferential statistical tests to analyze whether crash rates are statistically higher during construction time than during nonconstruction time at the same highway sections considering different crash severities (damages-only, injuries, and fatalities). Our database considered 871 road links that make up 68 artery corridors for the city of Bogota, and 5.450 road construction zones, from 2015 to 2019. An analysis by corridor was performed, in which we identified seven patterns in the behavior of accident rates influenced by the presence of a road intervention in the corridor. Within the patterns, it was evident that some corridors reported an increase in the accident rate during the time of construction, while others showed a decrease in the same comparison. We used the Wilcoxon test to establish the statistical significance of our conclusions, with a significance level of 10%. We also found that those construction interventions that do not require excavation of more than half a meter there was a decrease in the accident severity, as damages-only crashes, diminished during the construction time, while for those interventions that include excavation greater than half a meter there was an increase in overall accident rates during construction time.
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The final sections of main access roads to the cities require especial attention as the frequency of accidents in these road sections are considerably higher than other parts of interurban roads. These road sections operate as an interface between the rural roads and urban streets. The previous researches available on this subject are limited and they have also mainly focused on a narrow range of factors contributing to the accidents in these areas. The main contribution of this research is to consider a relatively comprehensive range of potential factors , and to examine their impacts through the development and comparison of both conventional probabilistic models and Artificial Neural Network (ANN) models. For this purpose, information related to the main access roads of three major Iranian cities were collected. This information consisted of accident frequency data together with the field observations of traffic characteristics, road-way conditions and roadside features of these ...
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Safety is typically linked to the road geometry and speed, and speed is directly associated to the road characteristics through the risk perceived by drivers. This endogeneous relationship is not reflected in the current approach of estimating speed and safety effects using single-equation models. This paper presents the results of a study that evaluated road design characteristics, free-flow speeds, crashes, and risk perception of drivers in four-lane highway segments located in suburban and rural areas. The results from single-equation speed and crash models were compared to speed and crash models developed simultaneously. The system of equations includes the effect of speed in the safety model while the effect of crash rate is included in the speed model. The road characteristics are considered exogenous variables in the system. The use of the simultaneous equations approach to calibrate the proposed system of relationships, aside from being the correct formulation to model the e...